Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

44 files changed, 5153 insertions, 0 deletions

diff --git a/webrtc/api/array_view.h b/webrtc/api/array_view.h
new file mode 100644
index 0000000..a66369a
--- /dev/null
+++ b/webrtc/api/array_view.h
@@ -0,0 +1,315 @@
+/*
+ *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_ARRAY_VIEW_H_
+#define API_ARRAY_VIEW_H_
+
+#include <algorithm>
+#include <array>
+#include <type_traits>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/type_traits.h"
+
+namespace rtc {
+
+// tl;dr: rtc::ArrayView is the same thing as gsl::span from the Guideline
+//        Support Library.
+//
+// Many functions read from or write to arrays. The obvious way to do this is
+// to use two arguments, a pointer to the first element and an element count:
+//
+//   bool Contains17(const int* arr, size_t size) {
+//     for (size_t i = 0; i < size; ++i) {
+//       if (arr[i] == 17)
+//         return true;
+//     }
+//     return false;
+//   }
+//
+// This is flexible, since it doesn't matter how the array is stored (C array,
+// std::vector, rtc::Buffer, ...), but it's error-prone because the caller has
+// to correctly specify the array length:
+//
+//   Contains17(arr, arraysize(arr));     // C array
+//   Contains17(arr.data(), arr.size());  // std::vector
+//   Contains17(arr, size);               // pointer + size
+//   ...
+//
+// It's also kind of messy to have two separate arguments for what is
+// conceptually a single thing.
+//
+// Enter rtc::ArrayView<T>. It contains a T pointer (to an array it doesn't
+// own) and a count, and supports the basic things you'd expect, such as
+// indexing and iteration. It allows us to write our function like this:
+//
+//   bool Contains17(rtc::ArrayView<const int> arr) {
+//     for (auto e : arr) {
+//       if (e == 17)
+//         return true;
+//     }
+//     return false;
+//   }
+//
+// And even better, because a bunch of things will implicitly convert to
+// ArrayView, we can call it like this:
+//
+//   Contains17(arr);                             // C array
+//   Contains17(arr);                             // std::vector
+//   Contains17(rtc::ArrayView<int>(arr, size));  // pointer + size
+//   Contains17(nullptr);                         // nullptr -> empty ArrayView
+//   ...
+//
+// ArrayView<T> stores both a pointer and a size, but you may also use
+// ArrayView<T, N>, which has a size that's fixed at compile time (which means
+// it only has to store the pointer).
+//
+// One important point is that ArrayView<T> and ArrayView<const T> are
+// different types, which allow and don't allow mutation of the array elements,
+// respectively. The implicit conversions work just like you'd hope, so that
+// e.g. vector<int> will convert to either ArrayView<int> or ArrayView<const
+// int>, but const vector<int> will convert only to ArrayView<const int>.
+// (ArrayView itself can be the source type in such conversions, so
+// ArrayView<int> will convert to ArrayView<const int>.)
+//
+// Note: ArrayView is tiny (just a pointer and a count if variable-sized, just
+// a pointer if fix-sized) and trivially copyable, so it's probably cheaper to
+// pass it by value than by const reference.
+
+namespace impl {
+
+// Magic constant for indicating that the size of an ArrayView is variable
+// instead of fixed.
+enum : std::ptrdiff_t { kArrayViewVarSize = -4711 };
+
+// Base class for ArrayViews of fixed nonzero size.
+template <typename T, std::ptrdiff_t Size>
+class ArrayViewBase {
+  static_assert(Size > 0, "ArrayView size must be variable or non-negative");
+
+ public:
+  ArrayViewBase(T* data, size_t size) : data_(data) {}
+
+  static constexpr size_t size() { return Size; }
+  static constexpr bool empty() { return false; }
+  T* data() const { return data_; }
+
+ protected:
+  static constexpr bool fixed_size() { return true; }
+
+ private:
+  T* data_;
+};
+
+// Specialized base class for ArrayViews of fixed zero size.
+template <typename T>
+class ArrayViewBase<T, 0> {
+ public:
+  explicit ArrayViewBase(T* data, size_t size) {}
+
+  static constexpr size_t size() { return 0; }
+  static constexpr bool empty() { return true; }
+  T* data() const { return nullptr; }
+
+ protected:
+  static constexpr bool fixed_size() { return true; }
+};
+
+// Specialized base class for ArrayViews of variable size.
+template <typename T>
+class ArrayViewBase<T, impl::kArrayViewVarSize> {
+ public:
+  ArrayViewBase(T* data, size_t size)
+      : data_(size == 0 ? nullptr : data), size_(size) {}
+
+  size_t size() const { return size_; }
+  bool empty() const { return size_ == 0; }
+  T* data() const { return data_; }
+
+ protected:
+  static constexpr bool fixed_size() { return false; }
+
+ private:
+  T* data_;
+  size_t size_;
+};
+
+}  // namespace impl
+
+template <typename T, std::ptrdiff_t Size = impl::kArrayViewVarSize>
+class ArrayView final : public impl::ArrayViewBase<T, Size> {
+ public:
+  using value_type = T;
+  using const_iterator = const T*;
+
+  // Construct an ArrayView from a pointer and a length.
+  template <typename U>
+  ArrayView(U* data, size_t size)
+      : impl::ArrayViewBase<T, Size>::ArrayViewBase(data, size) {
+    RTC_DCHECK_EQ(size == 0 ? nullptr : data, this->data());
+    RTC_DCHECK_EQ(size, this->size());
+    RTC_DCHECK_EQ(!this->data(),
+                  this->size() == 0);  // data is null iff size == 0.
+  }
+
+  // Construct an empty ArrayView. Note that fixed-size ArrayViews of size > 0
+  // cannot be empty.
+  ArrayView() : ArrayView(nullptr, 0) {}
+  ArrayView(std::nullptr_t)  // NOLINT
+      : ArrayView() {}
+  ArrayView(std::nullptr_t, size_t size)
+      : ArrayView(static_cast<T*>(nullptr), size) {
+    static_assert(Size == 0 || Size == impl::kArrayViewVarSize, "");
+    RTC_DCHECK_EQ(0, size);
+  }
+
+  // Construct an ArrayView from a C-style array.
+  template <typename U, size_t N>
+  ArrayView(U (&array)[N])  // NOLINT
+      : ArrayView(array, N) {
+    static_assert(Size == N || Size == impl::kArrayViewVarSize,
+                  "Array size must match ArrayView size");
+  }
+
+  // (Only if size is fixed.) Construct a fixed size ArrayView<T, N> from a
+  // non-const std::array instance. For an ArrayView with variable size, the
+  // used ctor is ArrayView(U& u) instead.
+  template <typename U,
+            size_t N,
+            typename std::enable_if<
+                Size == static_cast<std::ptrdiff_t>(N)>::type* = nullptr>
+  ArrayView(std::array<U, N>& u)  // NOLINT
+      : ArrayView(u.data(), u.size()) {}
+
+  // (Only if size is fixed.) Construct a fixed size ArrayView<T, N> where T is
+  // const from a const(expr) std::array instance. For an ArrayView with
+  // variable size, the used ctor is ArrayView(U& u) instead.
+  template <typename U,
+            size_t N,
+            typename std::enable_if<
+                Size == static_cast<std::ptrdiff_t>(N)>::type* = nullptr>
+  ArrayView(const std::array<U, N>& u)  // NOLINT
+      : ArrayView(u.data(), u.size()) {}
+
+  // (Only if size is fixed.) Construct an ArrayView from any type U that has a
+  // static constexpr size() method whose return value is equal to Size, and a
+  // data() method whose return value converts implicitly to T*. In particular,
+  // this means we allow conversion from ArrayView<T, N> to ArrayView<const T,
+  // N>, but not the other way around. We also don't allow conversion from
+  // ArrayView<T> to ArrayView<T, N>, or from ArrayView<T, M> to ArrayView<T,
+  // N> when M != N.
+  template <
+      typename U,
+      typename std::enable_if<Size != impl::kArrayViewVarSize &&
+                              HasDataAndSize<U, T>::value>::type* = nullptr>
+  ArrayView(U& u)  // NOLINT
+      : ArrayView(u.data(), u.size()) {
+    static_assert(U::size() == Size, "Sizes must match exactly");
+  }
+  template <
+      typename U,
+      typename std::enable_if<Size != impl::kArrayViewVarSize &&
+                              HasDataAndSize<U, T>::value>::type* = nullptr>
+  ArrayView(const U& u)  // NOLINT(runtime/explicit)
+      : ArrayView(u.data(), u.size()) {
+    static_assert(U::size() == Size, "Sizes must match exactly");
+  }
+
+  // (Only if size is variable.) Construct an ArrayView from any type U that
+  // has a size() method whose return value converts implicitly to size_t, and
+  // a data() method whose return value converts implicitly to T*. In
+  // particular, this means we allow conversion from ArrayView<T> to
+  // ArrayView<const T>, but not the other way around. Other allowed
+  // conversions include
+  // ArrayView<T, N> to ArrayView<T> or ArrayView<const T>,
+  // std::vector<T> to ArrayView<T> or ArrayView<const T>,
+  // const std::vector<T> to ArrayView<const T>,
+  // rtc::Buffer to ArrayView<uint8_t> or ArrayView<const uint8_t>, and
+  // const rtc::Buffer to ArrayView<const uint8_t>.
+  template <
+      typename U,
+      typename std::enable_if<Size == impl::kArrayViewVarSize &&
+                              HasDataAndSize<U, T>::value>::type* = nullptr>
+  ArrayView(U& u)  // NOLINT
+      : ArrayView(u.data(), u.size()) {}
+  template <
+      typename U,
+      typename std::enable_if<Size == impl::kArrayViewVarSize &&
+                              HasDataAndSize<U, T>::value>::type* = nullptr>
+  ArrayView(const U& u)  // NOLINT(runtime/explicit)
+      : ArrayView(u.data(), u.size()) {}
+
+  // Indexing and iteration. These allow mutation even if the ArrayView is
+  // const, because the ArrayView doesn't own the array. (To prevent mutation,
+  // use a const element type.)
+  T& operator[](size_t idx) const {
+    RTC_DCHECK_LT(idx, this->size());
+    RTC_DCHECK(this->data());
+    return this->data()[idx];
+  }
+  T* begin() const { return this->data(); }
+  T* end() const { return this->data() + this->size(); }
+  const T* cbegin() const { return this->data(); }
+  const T* cend() const { return this->data() + this->size(); }
+
+  ArrayView<T> subview(size_t offset, size_t size) const {
+    return offset < this->size()
+               ? ArrayView<T>(this->data() + offset,
+                              std::min(size, this->size() - offset))
+               : ArrayView<T>();
+  }
+  ArrayView<T> subview(size_t offset) const {
+    return subview(offset, this->size());
+  }
+};
+
+// Comparing two ArrayViews compares their (pointer,size) pairs; it does *not*
+// dereference the pointers.
+template <typename T, std::ptrdiff_t Size1, std::ptrdiff_t Size2>
+bool operator==(const ArrayView<T, Size1>& a, const ArrayView<T, Size2>& b) {
+  return a.data() == b.data() && a.size() == b.size();
+}
+template <typename T, std::ptrdiff_t Size1, std::ptrdiff_t Size2>
+bool operator!=(const ArrayView<T, Size1>& a, const ArrayView<T, Size2>& b) {
+  return !(a == b);
+}
+
+// Variable-size ArrayViews are the size of two pointers; fixed-size ArrayViews
+// are the size of one pointer. (And as a special case, fixed-size ArrayViews
+// of size 0 require no storage.)
+static_assert(sizeof(ArrayView<int>) == 2 * sizeof(int*), "");
+static_assert(sizeof(ArrayView<int, 17>) == sizeof(int*), "");
+static_assert(std::is_empty<ArrayView<int, 0>>::value, "");
+
+template <typename T>
+inline ArrayView<T> MakeArrayView(T* data, size_t size) {
+  return ArrayView<T>(data, size);
+}
+
+// Only for primitive types that have the same size and aligment.
+// Allow reinterpret cast of the array view to another primitive type of the
+// same size.
+// Template arguments order is (U, T, Size) to allow deduction of the template
+// arguments in client calls: reinterpret_array_view<target_type>(array_view).
+template <typename U, typename T, std::ptrdiff_t Size>
+inline ArrayView<U, Size> reinterpret_array_view(ArrayView<T, Size> view) {
+  static_assert(sizeof(U) == sizeof(T) && alignof(U) == alignof(T),
+                "ArrayView reinterpret_cast is only supported for casting "
+                "between views that represent the same chunk of memory.");
+  static_assert(
+      std::is_fundamental<T>::value && std::is_fundamental<U>::value,
+      "ArrayView reinterpret_cast is only supported for casting between "
+      "fundamental types.");
+  return ArrayView<U, Size>(reinterpret_cast<U*>(view.data()), view.size());
+}
+
+}  // namespace rtc
+
+#endif  // API_ARRAY_VIEW_H_
diff --git a/webrtc/api/audio/audio_frame.cc b/webrtc/api/audio/audio_frame.cc
new file mode 100644
index 0000000..c6e5cf4
--- /dev/null
+++ b/webrtc/api/audio/audio_frame.cc
@@ -0,0 +1,164 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/audio/audio_frame.h"
+
+#include <string.h>
+#include <algorithm>
+#include <utility>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/time_utils.h"
+
+namespace webrtc {
+
+AudioFrame::AudioFrame() {
+  // Visual Studio doesn't like this in the class definition.
+  static_assert(sizeof(data_) == kMaxDataSizeBytes, "kMaxDataSizeBytes");
+}
+
+void swap(AudioFrame& a, AudioFrame& b) {
+  using std::swap;
+  swap(a.timestamp_, b.timestamp_);
+  swap(a.elapsed_time_ms_, b.elapsed_time_ms_);
+  swap(a.ntp_time_ms_, b.ntp_time_ms_);
+  swap(a.samples_per_channel_, b.samples_per_channel_);
+  swap(a.sample_rate_hz_, b.sample_rate_hz_);
+  swap(a.num_channels_, b.num_channels_);
+  swap(a.channel_layout_, b.channel_layout_);
+  swap(a.speech_type_, b.speech_type_);
+  swap(a.vad_activity_, b.vad_activity_);
+  swap(a.profile_timestamp_ms_, b.profile_timestamp_ms_);
+  swap(a.packet_infos_, b.packet_infos_);
+  const size_t length_a = a.samples_per_channel_ * a.num_channels_;
+  const size_t length_b = b.samples_per_channel_ * b.num_channels_;
+  RTC_DCHECK_LE(length_a, AudioFrame::kMaxDataSizeSamples);
+  RTC_DCHECK_LE(length_b, AudioFrame::kMaxDataSizeSamples);
+  std::swap_ranges(a.data_, a.data_ + std::max(length_a, length_b), b.data_);
+  swap(a.muted_, b.muted_);
+  swap(a.absolute_capture_timestamp_ms_, b.absolute_capture_timestamp_ms_);
+}
+
+void AudioFrame::Reset() {
+  ResetWithoutMuting();
+  muted_ = true;
+}
+
+void AudioFrame::ResetWithoutMuting() {
+  // TODO(wu): Zero is a valid value for |timestamp_|. We should initialize
+  // to an invalid value, or add a new member to indicate invalidity.
+  timestamp_ = 0;
+  elapsed_time_ms_ = -1;
+  ntp_time_ms_ = -1;
+  samples_per_channel_ = 0;
+  sample_rate_hz_ = 0;
+  num_channels_ = 0;
+  channel_layout_ = CHANNEL_LAYOUT_NONE;
+  speech_type_ = kUndefined;
+  vad_activity_ = kVadUnknown;
+  profile_timestamp_ms_ = 0;
+  packet_infos_ = RtpPacketInfos();
+  absolute_capture_timestamp_ms_ = absl::nullopt;
+}
+
+void AudioFrame::UpdateFrame(uint32_t timestamp,
+                             const int16_t* data,
+                             size_t samples_per_channel,
+                             int sample_rate_hz,
+                             SpeechType speech_type,
+                             VADActivity vad_activity,
+                             size_t num_channels) {
+  timestamp_ = timestamp;
+  samples_per_channel_ = samples_per_channel;
+  sample_rate_hz_ = sample_rate_hz;
+  speech_type_ = speech_type;
+  vad_activity_ = vad_activity;
+  num_channels_ = num_channels;
+  channel_layout_ = GuessChannelLayout(num_channels);
+  if (channel_layout_ != CHANNEL_LAYOUT_UNSUPPORTED) {
+    RTC_DCHECK_EQ(num_channels, ChannelLayoutToChannelCount(channel_layout_));
+  }
+
+  const size_t length = samples_per_channel * num_channels;
+  RTC_CHECK_LE(length, kMaxDataSizeSamples);
+  if (data != nullptr) {
+    memcpy(data_, data, sizeof(int16_t) * length);
+    muted_ = false;
+  } else {
+    muted_ = true;
+  }
+}
+
+void AudioFrame::CopyFrom(const AudioFrame& src) {
+  if (this == &src)
+    return;
+
+  timestamp_ = src.timestamp_;
+  elapsed_time_ms_ = src.elapsed_time_ms_;
+  ntp_time_ms_ = src.ntp_time_ms_;
+  packet_infos_ = src.packet_infos_;
+  muted_ = src.muted();
+  samples_per_channel_ = src.samples_per_channel_;
+  sample_rate_hz_ = src.sample_rate_hz_;
+  speech_type_ = src.speech_type_;
+  vad_activity_ = src.vad_activity_;
+  num_channels_ = src.num_channels_;
+  channel_layout_ = src.channel_layout_;
+  absolute_capture_timestamp_ms_ = src.absolute_capture_timestamp_ms();
+
+  const size_t length = samples_per_channel_ * num_channels_;
+  RTC_CHECK_LE(length, kMaxDataSizeSamples);
+  if (!src.muted()) {
+    memcpy(data_, src.data(), sizeof(int16_t) * length);
+    muted_ = false;
+  }
+}
+
+void AudioFrame::UpdateProfileTimeStamp() {
+  profile_timestamp_ms_ = rtc::TimeMillis();
+}
+
+int64_t AudioFrame::ElapsedProfileTimeMs() const {
+  if (profile_timestamp_ms_ == 0) {
+    // Profiling has not been activated.
+    return -1;
+  }
+  return rtc::TimeSince(profile_timestamp_ms_);
+}
+
+const int16_t* AudioFrame::data() const {
+  return muted_ ? empty_data() : data_;
+}
+
+// TODO(henrik.lundin) Can we skip zeroing the buffer?
+// See https://bugs.chromium.org/p/webrtc/issues/detail?id=5647.
+int16_t* AudioFrame::mutable_data() {
+  if (muted_) {
+    memset(data_, 0, kMaxDataSizeBytes);
+    muted_ = false;
+  }
+  return data_;
+}
+
+void AudioFrame::Mute() {
+  muted_ = true;
+}
+
+bool AudioFrame::muted() const {
+  return muted_;
+}
+
+// static
+const int16_t* AudioFrame::empty_data() {
+  static int16_t* null_data = new int16_t[kMaxDataSizeSamples]();
+  return &null_data[0];
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/audio/audio_frame.h b/webrtc/api/audio/audio_frame.h
new file mode 100644
index 0000000..78539f5
--- /dev/null
+++ b/webrtc/api/audio/audio_frame.h
@@ -0,0 +1,177 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_AUDIO_AUDIO_FRAME_H_
+#define API_AUDIO_AUDIO_FRAME_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <utility>
+
+#include "api/audio/channel_layout.h"
+#include "api/rtp_packet_infos.h"
+#include "rtc_base/constructor_magic.h"
+
+namespace webrtc {
+
+/* This class holds up to 120 ms of super-wideband (32 kHz) stereo audio. It
+ * allows for adding and subtracting frames while keeping track of the resulting
+ * states.
+ *
+ * Notes
+ * - This is a de-facto api, not designed for external use. The AudioFrame class
+ *   is in need of overhaul or even replacement, and anyone depending on it
+ *   should be prepared for that.
+ * - The total number of samples is samples_per_channel_ * num_channels_.
+ * - Stereo data is interleaved starting with the left channel.
+ */
+class AudioFrame {
+ public:
+  // Using constexpr here causes linker errors unless the variable also has an
+  // out-of-class definition, which is impractical in this header-only class.
+  // (This makes no sense because it compiles as an enum value, which we most
+  // certainly cannot take the address of, just fine.) C++17 introduces inline
+  // variables which should allow us to switch to constexpr and keep this a
+  // header-only class.
+  enum : size_t {
+    // Stereo, 32 kHz, 120 ms (2 * 32 * 120)
+    // Stereo, 192 kHz, 20 ms (2 * 192 * 20)
+    kMaxDataSizeSamples = 7680,
+    kMaxDataSizeBytes = kMaxDataSizeSamples * sizeof(int16_t),
+  };
+
+  enum VADActivity { kVadActive = 0, kVadPassive = 1, kVadUnknown = 2 };
+  enum SpeechType {
+    kNormalSpeech = 0,
+    kPLC = 1,
+    kCNG = 2,
+    kPLCCNG = 3,
+    kCodecPLC = 5,
+    kUndefined = 4
+  };
+
+  AudioFrame();
+
+  friend void swap(AudioFrame& a, AudioFrame& b);
+
+  // Resets all members to their default state.
+  void Reset();
+  // Same as Reset(), but leaves mute state unchanged. Muting a frame requires
+  // the buffer to be zeroed on the next call to mutable_data(). Callers
+  // intending to write to the buffer immediately after Reset() can instead use
+  // ResetWithoutMuting() to skip this wasteful zeroing.
+  void ResetWithoutMuting();
+
+  void UpdateFrame(uint32_t timestamp,
+                   const int16_t* data,
+                   size_t samples_per_channel,
+                   int sample_rate_hz,
+                   SpeechType speech_type,
+                   VADActivity vad_activity,
+                   size_t num_channels = 1);
+
+  void CopyFrom(const AudioFrame& src);
+
+  // Sets a wall-time clock timestamp in milliseconds to be used for profiling
+  // of time between two points in the audio chain.
+  // Example:
+  //   t0: UpdateProfileTimeStamp()
+  //   t1: ElapsedProfileTimeMs() => t1 - t0 [msec]
+  void UpdateProfileTimeStamp();
+  // Returns the time difference between now and when UpdateProfileTimeStamp()
+  // was last called. Returns -1 if UpdateProfileTimeStamp() has not yet been
+  // called.
+  int64_t ElapsedProfileTimeMs() const;
+
+  // data() returns a zeroed static buffer if the frame is muted.
+  // mutable_frame() always returns a non-static buffer; the first call to
+  // mutable_frame() zeros the non-static buffer and marks the frame unmuted.
+  const int16_t* data() const;
+  int16_t* mutable_data();
+
+  // Prefer to mute frames using AudioFrameOperations::Mute.
+  void Mute();
+  // Frame is muted by default.
+  bool muted() const;
+
+  size_t max_16bit_samples() const { return kMaxDataSizeSamples; }
+  size_t samples_per_channel() const { return samples_per_channel_; }
+  size_t num_channels() const { return num_channels_; }
+  ChannelLayout channel_layout() const { return channel_layout_; }
+  int sample_rate_hz() const { return sample_rate_hz_; }
+
+  void set_absolute_capture_timestamp_ms(
+      int64_t absolute_capture_time_stamp_ms) {
+    absolute_capture_timestamp_ms_ = absolute_capture_time_stamp_ms;
+  }
+
+  absl::optional<int64_t> absolute_capture_timestamp_ms() const {
+    return absolute_capture_timestamp_ms_;
+  }
+
+  // RTP timestamp of the first sample in the AudioFrame.
+  uint32_t timestamp_ = 0;
+  // Time since the first frame in milliseconds.
+  // -1 represents an uninitialized value.
+  int64_t elapsed_time_ms_ = -1;
+  // NTP time of the estimated capture time in local timebase in milliseconds.
+  // -1 represents an uninitialized value.
+  int64_t ntp_time_ms_ = -1;
+  size_t samples_per_channel_ = 0;
+  int sample_rate_hz_ = 0;
+  size_t num_channels_ = 0;
+  ChannelLayout channel_layout_ = CHANNEL_LAYOUT_NONE;
+  SpeechType speech_type_ = kUndefined;
+  VADActivity vad_activity_ = kVadUnknown;
+  // Monotonically increasing timestamp intended for profiling of audio frames.
+  // Typically used for measuring elapsed time between two different points in
+  // the audio path. No lock is used to save resources and we are thread safe
+  // by design.
+  // TODO(nisse@webrtc.org): consider using absl::optional.
+  int64_t profile_timestamp_ms_ = 0;
+
+  // Information about packets used to assemble this audio frame. This is needed
+  // by |SourceTracker| when the frame is delivered to the RTCRtpReceiver's
+  // MediaStreamTrack, in order to implement getContributingSources(). See:
+  // https://w3c.github.io/webrtc-pc/#dom-rtcrtpreceiver-getcontributingsources
+  //
+  // TODO(bugs.webrtc.org/10757):
+  //   Note that this information might not be fully accurate since we currently
+  //   don't have a proper way to track it across the audio sync buffer. The
+  //   sync buffer is the small sample-holding buffer located after the audio
+  //   decoder and before where samples are assembled into output frames.
+  //
+  // |RtpPacketInfos| may also be empty if the audio samples did not come from
+  // RTP packets. E.g. if the audio were locally generated by packet loss
+  // concealment, comfort noise generation, etc.
+  RtpPacketInfos packet_infos_;
+
+ private:
+  // A permanently zeroed out buffer to represent muted frames. This is a
+  // header-only class, so the only way to avoid creating a separate empty
+  // buffer per translation unit is to wrap a static in an inline function.
+  static const int16_t* empty_data();
+
+  int16_t data_[kMaxDataSizeSamples];
+  bool muted_ = true;
+
+  // Absolute capture timestamp when this audio frame was originally captured.
+  // This is only valid for audio frames captured on this machine. The absolute
+  // capture timestamp of a received frame is found in |packet_infos_|.
+  // This timestamp MUST be based on the same clock as rtc::TimeMillis().
+  absl::optional<int64_t> absolute_capture_timestamp_ms_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(AudioFrame);
+};
+
+}  // namespace webrtc
+
+#endif  // API_AUDIO_AUDIO_FRAME_H_
diff --git a/webrtc/api/audio/channel_layout.cc b/webrtc/api/audio/channel_layout.cc
new file mode 100644
index 0000000..567f4d9
--- /dev/null
+++ b/webrtc/api/audio/channel_layout.cc
@@ -0,0 +1,282 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/audio/channel_layout.h"
+
+#include <stddef.h>
+
+#include "rtc_base/arraysize.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+
+static const int kLayoutToChannels[] = {
+    0,  // CHANNEL_LAYOUT_NONE
+    0,  // CHANNEL_LAYOUT_UNSUPPORTED
+    1,  // CHANNEL_LAYOUT_MONO
+    2,  // CHANNEL_LAYOUT_STEREO
+    3,  // CHANNEL_LAYOUT_2_1
+    3,  // CHANNEL_LAYOUT_SURROUND
+    4,  // CHANNEL_LAYOUT_4_0
+    4,  // CHANNEL_LAYOUT_2_2
+    4,  // CHANNEL_LAYOUT_QUAD
+    5,  // CHANNEL_LAYOUT_5_0
+    6,  // CHANNEL_LAYOUT_5_1
+    5,  // CHANNEL_LAYOUT_5_0_BACK
+    6,  // CHANNEL_LAYOUT_5_1_BACK
+    7,  // CHANNEL_LAYOUT_7_0
+    8,  // CHANNEL_LAYOUT_7_1
+    8,  // CHANNEL_LAYOUT_7_1_WIDE
+    2,  // CHANNEL_LAYOUT_STEREO_DOWNMIX
+    3,  // CHANNEL_LAYOUT_2POINT1
+    4,  // CHANNEL_LAYOUT_3_1
+    5,  // CHANNEL_LAYOUT_4_1
+    6,  // CHANNEL_LAYOUT_6_0
+    6,  // CHANNEL_LAYOUT_6_0_FRONT
+    6,  // CHANNEL_LAYOUT_HEXAGONAL
+    7,  // CHANNEL_LAYOUT_6_1
+    7,  // CHANNEL_LAYOUT_6_1_BACK
+    7,  // CHANNEL_LAYOUT_6_1_FRONT
+    7,  // CHANNEL_LAYOUT_7_0_FRONT
+    8,  // CHANNEL_LAYOUT_7_1_WIDE_BACK
+    8,  // CHANNEL_LAYOUT_OCTAGONAL
+    0,  // CHANNEL_LAYOUT_DISCRETE
+    3,  // CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC
+    5,  // CHANNEL_LAYOUT_4_1_QUAD_SIDE
+    0,  // CHANNEL_LAYOUT_BITSTREAM
+};
+
+// The channel orderings for each layout as specified by FFmpeg. Each value
+// represents the index of each channel in each layout.  Values of -1 mean the
+// channel at that index is not used for that layout. For example, the left side
+// surround sound channel in FFmpeg's 5.1 layout is in the 5th position (because
+// the order is L, R, C, LFE, LS, RS), so
+// kChannelOrderings[CHANNEL_LAYOUT_5_1][SIDE_LEFT] = 4;
+static const int kChannelOrderings[CHANNEL_LAYOUT_MAX + 1][CHANNELS_MAX + 1] = {
+    // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR
+
+    // CHANNEL_LAYOUT_NONE
+    {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_UNSUPPORTED
+    {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_MONO
+    {-1, -1, 0, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_STEREO
+    {0, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_2_1
+    {0, 1, -1, -1, -1, -1, -1, -1, 2, -1, -1},
+
+    // CHANNEL_LAYOUT_SURROUND
+    {0, 1, 2, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_4_0
+    {0, 1, 2, -1, -1, -1, -1, -1, 3, -1, -1},
+
+    // CHANNEL_LAYOUT_2_2
+    {0, 1, -1, -1, -1, -1, -1, -1, -1, 2, 3},
+
+    // CHANNEL_LAYOUT_QUAD
+    {0, 1, -1, -1, 2, 3, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_5_0
+    {0, 1, 2, -1, -1, -1, -1, -1, -1, 3, 4},
+
+    // CHANNEL_LAYOUT_5_1
+    {0, 1, 2, 3, -1, -1, -1, -1, -1, 4, 5},
+
+    // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR
+
+    // CHANNEL_LAYOUT_5_0_BACK
+    {0, 1, 2, -1, 3, 4, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_5_1_BACK
+    {0, 1, 2, 3, 4, 5, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_7_0
+    {0, 1, 2, -1, 5, 6, -1, -1, -1, 3, 4},
+
+    // CHANNEL_LAYOUT_7_1
+    {0, 1, 2, 3, 6, 7, -1, -1, -1, 4, 5},
+
+    // CHANNEL_LAYOUT_7_1_WIDE
+    {0, 1, 2, 3, -1, -1, 6, 7, -1, 4, 5},
+
+    // CHANNEL_LAYOUT_STEREO_DOWNMIX
+    {0, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_2POINT1
+    {0, 1, -1, 2, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_3_1
+    {0, 1, 2, 3, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_4_1
+    {0, 1, 2, 4, -1, -1, -1, -1, 3, -1, -1},
+
+    // CHANNEL_LAYOUT_6_0
+    {0, 1, 2, -1, -1, -1, -1, -1, 5, 3, 4},
+
+    // CHANNEL_LAYOUT_6_0_FRONT
+    {0, 1, -1, -1, -1, -1, 4, 5, -1, 2, 3},
+
+    // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR
+
+    // CHANNEL_LAYOUT_HEXAGONAL
+    {0, 1, 2, -1, 3, 4, -1, -1, 5, -1, -1},
+
+    // CHANNEL_LAYOUT_6_1
+    {0, 1, 2, 3, -1, -1, -1, -1, 6, 4, 5},
+
+    // CHANNEL_LAYOUT_6_1_BACK
+    {0, 1, 2, 3, 4, 5, -1, -1, 6, -1, -1},
+
+    // CHANNEL_LAYOUT_6_1_FRONT
+    {0, 1, -1, 6, -1, -1, 4, 5, -1, 2, 3},
+
+    // CHANNEL_LAYOUT_7_0_FRONT
+    {0, 1, 2, -1, -1, -1, 5, 6, -1, 3, 4},
+
+    // CHANNEL_LAYOUT_7_1_WIDE_BACK
+    {0, 1, 2, 3, 4, 5, 6, 7, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_OCTAGONAL
+    {0, 1, 2, -1, 5, 6, -1, -1, 7, 3, 4},
+
+    // CHANNEL_LAYOUT_DISCRETE
+    {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC
+    {0, 1, 2, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // CHANNEL_LAYOUT_4_1_QUAD_SIDE
+    {0, 1, -1, 4, -1, -1, -1, -1, -1, 2, 3},
+
+    // CHANNEL_LAYOUT_BITSTREAM
+    {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1},
+
+    // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR
+};
+
+int ChannelLayoutToChannelCount(ChannelLayout layout) {
+  RTC_DCHECK_LT(static_cast<size_t>(layout), arraysize(kLayoutToChannels));
+  RTC_DCHECK_LE(kLayoutToChannels[layout], kMaxConcurrentChannels);
+  return kLayoutToChannels[layout];
+}
+
+// Converts a channel count into a channel layout.
+ChannelLayout GuessChannelLayout(int channels) {
+  switch (channels) {
+    case 1:
+      return CHANNEL_LAYOUT_MONO;
+    case 2:
+      return CHANNEL_LAYOUT_STEREO;
+    case 3:
+      return CHANNEL_LAYOUT_SURROUND;
+    case 4:
+      return CHANNEL_LAYOUT_QUAD;
+    case 5:
+      return CHANNEL_LAYOUT_5_0;
+    case 6:
+      return CHANNEL_LAYOUT_5_1;
+    case 7:
+      return CHANNEL_LAYOUT_6_1;
+    case 8:
+      return CHANNEL_LAYOUT_7_1;
+    default:
+      RTC_DLOG(LS_WARNING) << "Unsupported channel count: " << channels;
+  }
+  return CHANNEL_LAYOUT_UNSUPPORTED;
+}
+
+int ChannelOrder(ChannelLayout layout, Channels channel) {
+  RTC_DCHECK_LT(static_cast<size_t>(layout), arraysize(kChannelOrderings));
+  RTC_DCHECK_LT(static_cast<size_t>(channel), arraysize(kChannelOrderings[0]));
+  return kChannelOrderings[layout][channel];
+}
+
+const char* ChannelLayoutToString(ChannelLayout layout) {
+  switch (layout) {
+    case CHANNEL_LAYOUT_NONE:
+      return "NONE";
+    case CHANNEL_LAYOUT_UNSUPPORTED:
+      return "UNSUPPORTED";
+    case CHANNEL_LAYOUT_MONO:
+      return "MONO";
+    case CHANNEL_LAYOUT_STEREO:
+      return "STEREO";
+    case CHANNEL_LAYOUT_2_1:
+      return "2.1";
+    case CHANNEL_LAYOUT_SURROUND:
+      return "SURROUND";
+    case CHANNEL_LAYOUT_4_0:
+      return "4.0";
+    case CHANNEL_LAYOUT_2_2:
+      return "QUAD_SIDE";
+    case CHANNEL_LAYOUT_QUAD:
+      return "QUAD";
+    case CHANNEL_LAYOUT_5_0:
+      return "5.0";
+    case CHANNEL_LAYOUT_5_1:
+      return "5.1";
+    case CHANNEL_LAYOUT_5_0_BACK:
+      return "5.0_BACK";
+    case CHANNEL_LAYOUT_5_1_BACK:
+      return "5.1_BACK";
+    case CHANNEL_LAYOUT_7_0:
+      return "7.0";
+    case CHANNEL_LAYOUT_7_1:
+      return "7.1";
+    case CHANNEL_LAYOUT_7_1_WIDE:
+      return "7.1_WIDE";
+    case CHANNEL_LAYOUT_STEREO_DOWNMIX:
+      return "STEREO_DOWNMIX";
+    case CHANNEL_LAYOUT_2POINT1:
+      return "2POINT1";
+    case CHANNEL_LAYOUT_3_1:
+      return "3.1";
+    case CHANNEL_LAYOUT_4_1:
+      return "4.1";
+    case CHANNEL_LAYOUT_6_0:
+      return "6.0";
+    case CHANNEL_LAYOUT_6_0_FRONT:
+      return "6.0_FRONT";
+    case CHANNEL_LAYOUT_HEXAGONAL:
+      return "HEXAGONAL";
+    case CHANNEL_LAYOUT_6_1:
+      return "6.1";
+    case CHANNEL_LAYOUT_6_1_BACK:
+      return "6.1_BACK";
+    case CHANNEL_LAYOUT_6_1_FRONT:
+      return "6.1_FRONT";
+    case CHANNEL_LAYOUT_7_0_FRONT:
+      return "7.0_FRONT";
+    case CHANNEL_LAYOUT_7_1_WIDE_BACK:
+      return "7.1_WIDE_BACK";
+    case CHANNEL_LAYOUT_OCTAGONAL:
+      return "OCTAGONAL";
+    case CHANNEL_LAYOUT_DISCRETE:
+      return "DISCRETE";
+    case CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC:
+      return "STEREO_AND_KEYBOARD_MIC";
+    case CHANNEL_LAYOUT_4_1_QUAD_SIDE:
+      return "4.1_QUAD_SIDE";
+    case CHANNEL_LAYOUT_BITSTREAM:
+      return "BITSTREAM";
+  }
+  RTC_NOTREACHED() << "Invalid channel layout provided: " << layout;
+  return "";
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/audio/channel_layout.h b/webrtc/api/audio/channel_layout.h
new file mode 100644
index 0000000..175aee7
--- /dev/null
+++ b/webrtc/api/audio/channel_layout.h
@@ -0,0 +1,165 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_AUDIO_CHANNEL_LAYOUT_H_
+#define API_AUDIO_CHANNEL_LAYOUT_H_
+
+namespace webrtc {
+
+// This file is derived from Chromium's base/channel_layout.h.
+
+// Enumerates the various representations of the ordering of audio channels.
+// Logged to UMA, so never reuse a value, always add new/greater ones!
+enum ChannelLayout {
+  CHANNEL_LAYOUT_NONE = 0,
+  CHANNEL_LAYOUT_UNSUPPORTED = 1,
+
+  // Front C
+  CHANNEL_LAYOUT_MONO = 2,
+
+  // Front L, Front R
+  CHANNEL_LAYOUT_STEREO = 3,
+
+  // Front L, Front R, Back C
+  CHANNEL_LAYOUT_2_1 = 4,
+
+  // Front L, Front R, Front C
+  CHANNEL_LAYOUT_SURROUND = 5,
+
+  // Front L, Front R, Front C, Back C
+  CHANNEL_LAYOUT_4_0 = 6,
+
+  // Front L, Front R, Side L, Side R
+  CHANNEL_LAYOUT_2_2 = 7,
+
+  // Front L, Front R, Back L, Back R
+  CHANNEL_LAYOUT_QUAD = 8,
+
+  // Front L, Front R, Front C, Side L, Side R
+  CHANNEL_LAYOUT_5_0 = 9,
+
+  // Front L, Front R, Front C, LFE, Side L, Side R
+  CHANNEL_LAYOUT_5_1 = 10,
+
+  // Front L, Front R, Front C, Back L, Back R
+  CHANNEL_LAYOUT_5_0_BACK = 11,
+
+  // Front L, Front R, Front C, LFE, Back L, Back R
+  CHANNEL_LAYOUT_5_1_BACK = 12,
+
+  // Front L, Front R, Front C, Side L, Side R, Back L, Back R
+  CHANNEL_LAYOUT_7_0 = 13,
+
+  // Front L, Front R, Front C, LFE, Side L, Side R, Back L, Back R
+  CHANNEL_LAYOUT_7_1 = 14,
+
+  // Front L, Front R, Front C, LFE, Side L, Side R, Front LofC, Front RofC
+  CHANNEL_LAYOUT_7_1_WIDE = 15,
+
+  // Stereo L, Stereo R
+  CHANNEL_LAYOUT_STEREO_DOWNMIX = 16,
+
+  // Stereo L, Stereo R, LFE
+  CHANNEL_LAYOUT_2POINT1 = 17,
+
+  // Stereo L, Stereo R, Front C, LFE
+  CHANNEL_LAYOUT_3_1 = 18,
+
+  // Stereo L, Stereo R, Front C, Rear C, LFE
+  CHANNEL_LAYOUT_4_1 = 19,
+
+  // Stereo L, Stereo R, Front C, Side L, Side R, Back C
+  CHANNEL_LAYOUT_6_0 = 20,
+
+  // Stereo L, Stereo R, Side L, Side R, Front LofC, Front RofC
+  CHANNEL_LAYOUT_6_0_FRONT = 21,
+
+  // Stereo L, Stereo R, Front C, Rear L, Rear R, Rear C
+  CHANNEL_LAYOUT_HEXAGONAL = 22,
+
+  // Stereo L, Stereo R, Front C, LFE, Side L, Side R, Rear Center
+  CHANNEL_LAYOUT_6_1 = 23,
+
+  // Stereo L, Stereo R, Front C, LFE, Back L, Back R, Rear Center
+  CHANNEL_LAYOUT_6_1_BACK = 24,
+
+  // Stereo L, Stereo R, Side L, Side R, Front LofC, Front RofC, LFE
+  CHANNEL_LAYOUT_6_1_FRONT = 25,
+
+  // Front L, Front R, Front C, Side L, Side R, Front LofC, Front RofC
+  CHANNEL_LAYOUT_7_0_FRONT = 26,
+
+  // Front L, Front R, Front C, LFE, Back L, Back R, Front LofC, Front RofC
+  CHANNEL_LAYOUT_7_1_WIDE_BACK = 27,
+
+  // Front L, Front R, Front C, Side L, Side R, Rear L, Back R, Back C.
+  CHANNEL_LAYOUT_OCTAGONAL = 28,
+
+  // Channels are not explicitly mapped to speakers.
+  CHANNEL_LAYOUT_DISCRETE = 29,
+
+  // Front L, Front R, Front C. Front C contains the keyboard mic audio. This
+  // layout is only intended for input for WebRTC. The Front C channel
+  // is stripped away in the WebRTC audio input pipeline and never seen outside
+  // of that.
+  CHANNEL_LAYOUT_STEREO_AND_KEYBOARD_MIC = 30,
+
+  // Front L, Front R, Side L, Side R, LFE
+  CHANNEL_LAYOUT_4_1_QUAD_SIDE = 31,
+
+  // Actual channel layout is specified in the bitstream and the actual channel
+  // count is unknown at Chromium media pipeline level (useful for audio
+  // pass-through mode).
+  CHANNEL_LAYOUT_BITSTREAM = 32,
+
+  // Max value, must always equal the largest entry ever logged.
+  CHANNEL_LAYOUT_MAX = CHANNEL_LAYOUT_BITSTREAM
+};
+
+// Note: Do not reorder or reassign these values; other code depends on their
+// ordering to operate correctly. E.g., CoreAudio channel layout computations.
+enum Channels {
+  LEFT = 0,
+  RIGHT,
+  CENTER,
+  LFE,
+  BACK_LEFT,
+  BACK_RIGHT,
+  LEFT_OF_CENTER,
+  RIGHT_OF_CENTER,
+  BACK_CENTER,
+  SIDE_LEFT,
+  SIDE_RIGHT,
+  CHANNELS_MAX =
+      SIDE_RIGHT,  // Must always equal the largest value ever logged.
+};
+
+// The maximum number of concurrently active channels for all possible layouts.
+// ChannelLayoutToChannelCount() will never return a value higher than this.
+constexpr int kMaxConcurrentChannels = 8;
+
+// Returns the expected channel position in an interleaved stream.  Values of -1
+// mean the channel at that index is not used for that layout.  Values range
+// from 0 to ChannelLayoutToChannelCount(layout) - 1.
+int ChannelOrder(ChannelLayout layout, Channels channel);
+
+// Returns the number of channels in a given ChannelLayout.
+int ChannelLayoutToChannelCount(ChannelLayout layout);
+
+// Given the number of channels, return the best layout,
+// or return CHANNEL_LAYOUT_UNSUPPORTED if there is no good match.
+ChannelLayout GuessChannelLayout(int channels);
+
+// Returns a string representation of the channel layout.
+const char* ChannelLayoutToString(ChannelLayout layout);
+
+}  // namespace webrtc
+
+#endif  // API_AUDIO_CHANNEL_LAYOUT_H_
diff --git a/webrtc/api/audio/echo_canceller3_config.cc b/webrtc/api/audio/echo_canceller3_config.cc
new file mode 100644
index 0000000..aeb809e
--- /dev/null
+++ b/webrtc/api/audio/echo_canceller3_config.cc
@@ -0,0 +1,270 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include "api/audio/echo_canceller3_config.h"
+
+#include <algorithm>
+#include <cmath>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_minmax.h"
+
+namespace webrtc {
+namespace {
+bool Limit(float* value, float min, float max) {
+  float clamped = rtc::SafeClamp(*value, min, max);
+  clamped = std::isfinite(clamped) ? clamped : min;
+  bool res = *value == clamped;
+  *value = clamped;
+  return res;
+}
+
+bool Limit(size_t* value, size_t min, size_t max) {
+  size_t clamped = rtc::SafeClamp(*value, min, max);
+  bool res = *value == clamped;
+  *value = clamped;
+  return res;
+}
+
+bool Limit(int* value, int min, int max) {
+  int clamped = rtc::SafeClamp(*value, min, max);
+  bool res = *value == clamped;
+  *value = clamped;
+  return res;
+}
+
+bool FloorLimit(size_t* value, size_t min) {
+  size_t clamped = *value >= min ? *value : min;
+  bool res = *value == clamped;
+  *value = clamped;
+  return res;
+}
+
+}  // namespace
+
+EchoCanceller3Config::EchoCanceller3Config() = default;
+EchoCanceller3Config::EchoCanceller3Config(const EchoCanceller3Config& e) =
+    default;
+EchoCanceller3Config& EchoCanceller3Config::operator=(
+    const EchoCanceller3Config& e) = default;
+EchoCanceller3Config::Delay::Delay() = default;
+EchoCanceller3Config::Delay::Delay(const EchoCanceller3Config::Delay& e) =
+    default;
+EchoCanceller3Config::Delay& EchoCanceller3Config::Delay::operator=(
+    const Delay& e) = default;
+
+EchoCanceller3Config::EchoModel::EchoModel() = default;
+EchoCanceller3Config::EchoModel::EchoModel(
+    const EchoCanceller3Config::EchoModel& e) = default;
+EchoCanceller3Config::EchoModel& EchoCanceller3Config::EchoModel::operator=(
+    const EchoModel& e) = default;
+
+EchoCanceller3Config::Suppressor::Suppressor() = default;
+EchoCanceller3Config::Suppressor::Suppressor(
+    const EchoCanceller3Config::Suppressor& e) = default;
+EchoCanceller3Config::Suppressor& EchoCanceller3Config::Suppressor::operator=(
+    const Suppressor& e) = default;
+
+EchoCanceller3Config::Suppressor::MaskingThresholds::MaskingThresholds(
+    float enr_transparent,
+    float enr_suppress,
+    float emr_transparent)
+    : enr_transparent(enr_transparent),
+      enr_suppress(enr_suppress),
+      emr_transparent(emr_transparent) {}
+EchoCanceller3Config::Suppressor::MaskingThresholds::MaskingThresholds(
+    const EchoCanceller3Config::Suppressor::MaskingThresholds& e) = default;
+EchoCanceller3Config::Suppressor::MaskingThresholds&
+EchoCanceller3Config::Suppressor::MaskingThresholds::operator=(
+    const MaskingThresholds& e) = default;
+
+EchoCanceller3Config::Suppressor::Tuning::Tuning(MaskingThresholds mask_lf,
+                                                 MaskingThresholds mask_hf,
+                                                 float max_inc_factor,
+                                                 float max_dec_factor_lf)
+    : mask_lf(mask_lf),
+      mask_hf(mask_hf),
+      max_inc_factor(max_inc_factor),
+      max_dec_factor_lf(max_dec_factor_lf) {}
+EchoCanceller3Config::Suppressor::Tuning::Tuning(
+    const EchoCanceller3Config::Suppressor::Tuning& e) = default;
+EchoCanceller3Config::Suppressor::Tuning&
+EchoCanceller3Config::Suppressor::Tuning::operator=(const Tuning& e) = default;
+
+bool EchoCanceller3Config::Validate(EchoCanceller3Config* config) {
+  RTC_DCHECK(config);
+  EchoCanceller3Config* c = config;
+  bool res = true;
+
+  if (c->delay.down_sampling_factor != 4 &&
+      c->delay.down_sampling_factor != 8) {
+    c->delay.down_sampling_factor = 4;
+    res = false;
+  }
+
+  res = res & Limit(&c->delay.default_delay, 0, 5000);
+  res = res & Limit(&c->delay.num_filters, 0, 5000);
+  res = res & Limit(&c->delay.delay_headroom_samples, 0, 5000);
+  res = res & Limit(&c->delay.hysteresis_limit_blocks, 0, 5000);
+  res = res & Limit(&c->delay.fixed_capture_delay_samples, 0, 5000);
+  res = res & Limit(&c->delay.delay_estimate_smoothing, 0.f, 1.f);
+  res = res & Limit(&c->delay.delay_candidate_detection_threshold, 0.f, 1.f);
+  res = res & Limit(&c->delay.delay_selection_thresholds.initial, 1, 250);
+  res = res & Limit(&c->delay.delay_selection_thresholds.converged, 1, 250);
+
+  res = res & FloorLimit(&c->filter.refined.length_blocks, 1);
+  res = res & Limit(&c->filter.refined.leakage_converged, 0.f, 1000.f);
+  res = res & Limit(&c->filter.refined.leakage_diverged, 0.f, 1000.f);
+  res = res & Limit(&c->filter.refined.error_floor, 0.f, 1000.f);
+  res = res & Limit(&c->filter.refined.error_ceil, 0.f, 100000000.f);
+  res = res & Limit(&c->filter.refined.noise_gate, 0.f, 100000000.f);
+
+  res = res & FloorLimit(&c->filter.refined_initial.length_blocks, 1);
+  res = res & Limit(&c->filter.refined_initial.leakage_converged, 0.f, 1000.f);
+  res = res & Limit(&c->filter.refined_initial.leakage_diverged, 0.f, 1000.f);
+  res = res & Limit(&c->filter.refined_initial.error_floor, 0.f, 1000.f);
+  res = res & Limit(&c->filter.refined_initial.error_ceil, 0.f, 100000000.f);
+  res = res & Limit(&c->filter.refined_initial.noise_gate, 0.f, 100000000.f);
+
+  if (c->filter.refined.length_blocks <
+      c->filter.refined_initial.length_blocks) {
+    c->filter.refined_initial.length_blocks = c->filter.refined.length_blocks;
+    res = false;
+  }
+
+  res = res & FloorLimit(&c->filter.coarse.length_blocks, 1);
+  res = res & Limit(&c->filter.coarse.rate, 0.f, 1.f);
+  res = res & Limit(&c->filter.coarse.noise_gate, 0.f, 100000000.f);
+
+  res = res & FloorLimit(&c->filter.coarse_initial.length_blocks, 1);
+  res = res & Limit(&c->filter.coarse_initial.rate, 0.f, 1.f);
+  res = res & Limit(&c->filter.coarse_initial.noise_gate, 0.f, 100000000.f);
+
+  if (c->filter.coarse.length_blocks < c->filter.coarse_initial.length_blocks) {
+    c->filter.coarse_initial.length_blocks = c->filter.coarse.length_blocks;
+    res = false;
+  }
+
+  res = res & Limit(&c->filter.config_change_duration_blocks, 0, 100000);
+  res = res & Limit(&c->filter.initial_state_seconds, 0.f, 100.f);
+
+  res = res & Limit(&c->erle.min, 1.f, 100000.f);
+  res = res & Limit(&c->erle.max_l, 1.f, 100000.f);
+  res = res & Limit(&c->erle.max_h, 1.f, 100000.f);
+  if (c->erle.min > c->erle.max_l || c->erle.min > c->erle.max_h) {
+    c->erle.min = std::min(c->erle.max_l, c->erle.max_h);
+    res = false;
+  }
+  res = res & Limit(&c->erle.num_sections, 1, c->filter.refined.length_blocks);
+
+  res = res & Limit(&c->ep_strength.default_gain, 0.f, 1000000.f);
+  res = res & Limit(&c->ep_strength.default_len, -1.f, 1.f);
+
+  res =
+      res & Limit(&c->echo_audibility.low_render_limit, 0.f, 32768.f * 32768.f);
+  res = res &
+        Limit(&c->echo_audibility.normal_render_limit, 0.f, 32768.f * 32768.f);
+  res = res & Limit(&c->echo_audibility.floor_power, 0.f, 32768.f * 32768.f);
+  res = res & Limit(&c->echo_audibility.audibility_threshold_lf, 0.f,
+                    32768.f * 32768.f);
+  res = res & Limit(&c->echo_audibility.audibility_threshold_mf, 0.f,
+                    32768.f * 32768.f);
+  res = res & Limit(&c->echo_audibility.audibility_threshold_hf, 0.f,
+                    32768.f * 32768.f);
+
+  res = res &
+        Limit(&c->render_levels.active_render_limit, 0.f, 32768.f * 32768.f);
+  res = res & Limit(&c->render_levels.poor_excitation_render_limit, 0.f,
+                    32768.f * 32768.f);
+  res = res & Limit(&c->render_levels.poor_excitation_render_limit_ds8, 0.f,
+                    32768.f * 32768.f);
+
+  res = res & Limit(&c->echo_model.noise_floor_hold, 0, 1000);
+  res = res & Limit(&c->echo_model.min_noise_floor_power, 0, 2000000.f);
+  res = res & Limit(&c->echo_model.stationary_gate_slope, 0, 1000000.f);
+  res = res & Limit(&c->echo_model.noise_gate_power, 0, 1000000.f);
+  res = res & Limit(&c->echo_model.noise_gate_slope, 0, 1000000.f);
+  res = res & Limit(&c->echo_model.render_pre_window_size, 0, 100);
+  res = res & Limit(&c->echo_model.render_post_window_size, 0, 100);
+
+  res = res & Limit(&c->comfort_noise.noise_floor_dbfs, -200.f, 0.f);
+
+  res = res & Limit(&c->suppressor.nearend_average_blocks, 1, 5000);
+
+  res = res &
+        Limit(&c->suppressor.normal_tuning.mask_lf.enr_transparent, 0.f, 100.f);
+  res = res &
+        Limit(&c->suppressor.normal_tuning.mask_lf.enr_suppress, 0.f, 100.f);
+  res = res &
+        Limit(&c->suppressor.normal_tuning.mask_lf.emr_transparent, 0.f, 100.f);
+  res = res &
+        Limit(&c->suppressor.normal_tuning.mask_hf.enr_transparent, 0.f, 100.f);
+  res = res &
+        Limit(&c->suppressor.normal_tuning.mask_hf.enr_suppress, 0.f, 100.f);
+  res = res &
+        Limit(&c->suppressor.normal_tuning.mask_hf.emr_transparent, 0.f, 100.f);
+  res = res & Limit(&c->suppressor.normal_tuning.max_inc_factor, 0.f, 100.f);
+  res = res & Limit(&c->suppressor.normal_tuning.max_dec_factor_lf, 0.f, 100.f);
+
+  res = res & Limit(&c->suppressor.nearend_tuning.mask_lf.enr_transparent, 0.f,
+                    100.f);
+  res = res &
+        Limit(&c->suppressor.nearend_tuning.mask_lf.enr_suppress, 0.f, 100.f);
+  res = res & Limit(&c->suppressor.nearend_tuning.mask_lf.emr_transparent, 0.f,
+                    100.f);
+  res = res & Limit(&c->suppressor.nearend_tuning.mask_hf.enr_transparent, 0.f,
+                    100.f);
+  res = res &
+        Limit(&c->suppressor.nearend_tuning.mask_hf.enr_suppress, 0.f, 100.f);
+  res = res & Limit(&c->suppressor.nearend_tuning.mask_hf.emr_transparent, 0.f,
+                    100.f);
+  res = res & Limit(&c->suppressor.nearend_tuning.max_inc_factor, 0.f, 100.f);
+  res =
+      res & Limit(&c->suppressor.nearend_tuning.max_dec_factor_lf, 0.f, 100.f);
+
+  res = res & Limit(&c->suppressor.dominant_nearend_detection.enr_threshold,
+                    0.f, 1000000.f);
+  res = res & Limit(&c->suppressor.dominant_nearend_detection.snr_threshold,
+                    0.f, 1000000.f);
+  res = res & Limit(&c->suppressor.dominant_nearend_detection.hold_duration, 0,
+                    10000);
+  res = res & Limit(&c->suppressor.dominant_nearend_detection.trigger_threshold,
+                    0, 10000);
+
+  res = res &
+        Limit(&c->suppressor.subband_nearend_detection.nearend_average_blocks,
+              1, 1024);
+  res =
+      res & Limit(&c->suppressor.subband_nearend_detection.subband1.low, 0, 65);
+  res = res & Limit(&c->suppressor.subband_nearend_detection.subband1.high,
+                    c->suppressor.subband_nearend_detection.subband1.low, 65);
+  res =
+      res & Limit(&c->suppressor.subband_nearend_detection.subband2.low, 0, 65);
+  res = res & Limit(&c->suppressor.subband_nearend_detection.subband2.high,
+                    c->suppressor.subband_nearend_detection.subband2.low, 65);
+  res = res & Limit(&c->suppressor.subband_nearend_detection.nearend_threshold,
+                    0.f, 1.e24f);
+  res = res & Limit(&c->suppressor.subband_nearend_detection.snr_threshold, 0.f,
+                    1.e24f);
+
+  res = res & Limit(&c->suppressor.high_bands_suppression.enr_threshold, 0.f,
+                    1000000.f);
+  res = res & Limit(&c->suppressor.high_bands_suppression.max_gain_during_echo,
+                    0.f, 1.f);
+  res = res & Limit(&c->suppressor.high_bands_suppression
+                         .anti_howling_activation_threshold,
+                    0.f, 32768.f * 32768.f);
+  res = res & Limit(&c->suppressor.high_bands_suppression.anti_howling_gain,
+                    0.f, 1.f);
+
+  res = res & Limit(&c->suppressor.floor_first_increase, 0.f, 1000000.f);
+
+  return res;
+}
+}  // namespace webrtc
diff --git a/webrtc/api/audio/echo_canceller3_config.h b/webrtc/api/audio/echo_canceller3_config.h
new file mode 100644
index 0000000..af57d04
--- /dev/null
+++ b/webrtc/api/audio/echo_canceller3_config.h
@@ -0,0 +1,228 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_AUDIO_ECHO_CANCELLER3_CONFIG_H_
+#define API_AUDIO_ECHO_CANCELLER3_CONFIG_H_
+
+#include <stddef.h>  // size_t
+
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+// Configuration struct for EchoCanceller3
+struct RTC_EXPORT EchoCanceller3Config {
+  // Checks and updates the config parameters to lie within (mostly) reasonable
+  // ranges. Returns true if and only of the config did not need to be changed.
+  static bool Validate(EchoCanceller3Config* config);
+
+  EchoCanceller3Config();
+  EchoCanceller3Config(const EchoCanceller3Config& e);
+  EchoCanceller3Config& operator=(const EchoCanceller3Config& other);
+
+  struct Buffering {
+    size_t excess_render_detection_interval_blocks = 250;
+    size_t max_allowed_excess_render_blocks = 8;
+  } buffering;
+
+  struct Delay {
+    Delay();
+    Delay(const Delay& e);
+    Delay& operator=(const Delay& e);
+    size_t default_delay = 5;
+    size_t down_sampling_factor = 4;
+    size_t num_filters = 5;
+    size_t delay_headroom_samples = 32;
+    size_t hysteresis_limit_blocks = 1;
+    size_t fixed_capture_delay_samples = 0;
+    float delay_estimate_smoothing = 0.7f;
+    float delay_candidate_detection_threshold = 0.2f;
+    struct DelaySelectionThresholds {
+      int initial;
+      int converged;
+    } delay_selection_thresholds = {5, 20};
+    bool use_external_delay_estimator = false;
+    bool log_warning_on_delay_changes = false;
+    struct AlignmentMixing {
+      bool downmix;
+      bool adaptive_selection;
+      float activity_power_threshold;
+      bool prefer_first_two_channels;
+    };
+    AlignmentMixing render_alignment_mixing = {false, true, 10000.f, true};
+    AlignmentMixing capture_alignment_mixing = {false, true, 10000.f, false};
+  } delay;
+
+  struct Filter {
+    struct RefinedConfiguration {
+      size_t length_blocks;
+      float leakage_converged;
+      float leakage_diverged;
+      float error_floor;
+      float error_ceil;
+      float noise_gate;
+    };
+
+    struct CoarseConfiguration {
+      size_t length_blocks;
+      float rate;
+      float noise_gate;
+    };
+
+    RefinedConfiguration refined = {13,     0.00005f, 0.05f,
+                                    0.001f, 2.f,      20075344.f};
+    CoarseConfiguration coarse = {13, 0.7f, 20075344.f};
+
+    RefinedConfiguration refined_initial = {12,     0.005f, 0.5f,
+                                            0.001f, 2.f,    20075344.f};
+    CoarseConfiguration coarse_initial = {12, 0.9f, 20075344.f};
+
+    size_t config_change_duration_blocks = 250;
+    float initial_state_seconds = 2.5f;
+    bool conservative_initial_phase = false;
+    bool enable_coarse_filter_output_usage = true;
+    bool use_linear_filter = true;
+    bool export_linear_aec_output = false;
+  } filter;
+
+  struct Erle {
+    float min = 1.f;
+    float max_l = 4.f;
+    float max_h = 1.5f;
+    bool onset_detection = true;
+    size_t num_sections = 1;
+    bool clamp_quality_estimate_to_zero = true;
+    bool clamp_quality_estimate_to_one = true;
+  } erle;
+
+  struct EpStrength {
+    float default_gain = 1.f;
+    float default_len = 0.83f;
+    bool echo_can_saturate = true;
+    bool bounded_erl = false;
+  } ep_strength;
+
+  struct EchoAudibility {
+    float low_render_limit = 4 * 64.f;
+    float normal_render_limit = 64.f;
+    float floor_power = 2 * 64.f;
+    float audibility_threshold_lf = 10;
+    float audibility_threshold_mf = 10;
+    float audibility_threshold_hf = 10;
+    bool use_stationarity_properties = false;
+    bool use_stationarity_properties_at_init = false;
+  } echo_audibility;
+
+  struct RenderLevels {
+    float active_render_limit = 100.f;
+    float poor_excitation_render_limit = 150.f;
+    float poor_excitation_render_limit_ds8 = 20.f;
+    float render_power_gain_db = 0.f;
+  } render_levels;
+
+  struct EchoRemovalControl {
+    bool has_clock_drift = false;
+    bool linear_and_stable_echo_path = false;
+  } echo_removal_control;
+
+  struct EchoModel {
+    EchoModel();
+    EchoModel(const EchoModel& e);
+    EchoModel& operator=(const EchoModel& e);
+    size_t noise_floor_hold = 50;
+    float min_noise_floor_power = 1638400.f;
+    float stationary_gate_slope = 10.f;
+    float noise_gate_power = 27509.42f;
+    float noise_gate_slope = 0.3f;
+    size_t render_pre_window_size = 1;
+    size_t render_post_window_size = 1;
+    bool model_reverb_in_nonlinear_mode = true;
+  } echo_model;
+
+  struct ComfortNoise {
+    float noise_floor_dbfs = -96.03406f;
+  } comfort_noise;
+
+  struct Suppressor {
+    Suppressor();
+    Suppressor(const Suppressor& e);
+    Suppressor& operator=(const Suppressor& e);
+
+    size_t nearend_average_blocks = 4;
+
+    struct MaskingThresholds {
+      MaskingThresholds(float enr_transparent,
+                        float enr_suppress,
+                        float emr_transparent);
+      MaskingThresholds(const MaskingThresholds& e);
+      MaskingThresholds& operator=(const MaskingThresholds& e);
+      float enr_transparent;
+      float enr_suppress;
+      float emr_transparent;
+    };
+
+    struct Tuning {
+      Tuning(MaskingThresholds mask_lf,
+             MaskingThresholds mask_hf,
+             float max_inc_factor,
+             float max_dec_factor_lf);
+      Tuning(const Tuning& e);
+      Tuning& operator=(const Tuning& e);
+      MaskingThresholds mask_lf;
+      MaskingThresholds mask_hf;
+      float max_inc_factor;
+      float max_dec_factor_lf;
+    };
+
+    Tuning normal_tuning = Tuning(MaskingThresholds(.3f, .4f, .3f),
+                                  MaskingThresholds(.07f, .1f, .3f),
+                                  2.0f,
+                                  0.25f);
+    Tuning nearend_tuning = Tuning(MaskingThresholds(1.09f, 1.1f, .3f),
+                                   MaskingThresholds(.1f, .3f, .3f),
+                                   2.0f,
+                                   0.25f);
+
+    struct DominantNearendDetection {
+      float enr_threshold = .25f;
+      float enr_exit_threshold = 10.f;
+      float snr_threshold = 30.f;
+      int hold_duration = 50;
+      int trigger_threshold = 12;
+      bool use_during_initial_phase = true;
+    } dominant_nearend_detection;
+
+    struct SubbandNearendDetection {
+      size_t nearend_average_blocks = 1;
+      struct SubbandRegion {
+        size_t low;
+        size_t high;
+      };
+      SubbandRegion subband1 = {1, 1};
+      SubbandRegion subband2 = {1, 1};
+      float nearend_threshold = 1.f;
+      float snr_threshold = 1.f;
+    } subband_nearend_detection;
+
+    bool use_subband_nearend_detection = false;
+
+    struct HighBandsSuppression {
+      float enr_threshold = 1.f;
+      float max_gain_during_echo = 1.f;
+      float anti_howling_activation_threshold = 400.f;
+      float anti_howling_gain = 1.f;
+    } high_bands_suppression;
+
+    float floor_first_increase = 0.00001f;
+  } suppressor;
+};
+}  // namespace webrtc
+
+#endif  // API_AUDIO_ECHO_CANCELLER3_CONFIG_H_
diff --git a/webrtc/api/audio/echo_control.h b/webrtc/api/audio/echo_control.h
new file mode 100644
index 0000000..8d567bf
--- /dev/null
+++ b/webrtc/api/audio/echo_control.h
@@ -0,0 +1,68 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_AUDIO_ECHO_CONTROL_H_
+#define API_AUDIO_ECHO_CONTROL_H_
+
+#include <memory>
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+
+class AudioBuffer;
+
+// Interface for an acoustic echo cancellation (AEC) submodule.
+class EchoControl {
+ public:
+  // Analysis (not changing) of the render signal.
+  virtual void AnalyzeRender(AudioBuffer* render) = 0;
+
+  // Analysis (not changing) of the capture signal.
+  virtual void AnalyzeCapture(AudioBuffer* capture) = 0;
+
+  // Processes the capture signal in order to remove the echo.
+  virtual void ProcessCapture(AudioBuffer* capture, bool level_change) = 0;
+
+  // As above, but also returns the linear filter output.
+  virtual void ProcessCapture(AudioBuffer* capture,
+                              AudioBuffer* linear_output,
+                              bool level_change) = 0;
+
+  struct Metrics {
+    double echo_return_loss;
+    double echo_return_loss_enhancement;
+    int delay_ms;
+  };
+
+  // Collect current metrics from the echo controller.
+  virtual Metrics GetMetrics() const = 0;
+
+  // Provides an optional external estimate of the audio buffer delay.
+  virtual void SetAudioBufferDelay(int delay_ms) = 0;
+
+  // Returns wheter the signal is altered.
+  virtual bool ActiveProcessing() const = 0;
+
+  virtual ~EchoControl() {}
+};
+
+// Interface for a factory that creates EchoControllers.
+class EchoControlFactory {
+ public:
+  virtual std::unique_ptr<EchoControl> Create(int sample_rate_hz,
+                                              int num_render_channels,
+                                              int num_capture_channels) = 0;
+
+  virtual ~EchoControlFactory() = default;
+};
+}  // namespace webrtc
+
+#endif  // API_AUDIO_ECHO_CONTROL_H_
diff --git a/webrtc/api/audio_codecs/audio_decoder.cc b/webrtc/api/audio_codecs/audio_decoder.cc
new file mode 100644
index 0000000..97cda27
--- /dev/null
+++ b/webrtc/api/audio_codecs/audio_decoder.cc
@@ -0,0 +1,170 @@
+/*
+ *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/audio_codecs/audio_decoder.h"
+
+#include <assert.h>
+
+#include <memory>
+#include <utility>
+
+#include "api/array_view.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/sanitizer.h"
+#include "rtc_base/trace_event.h"
+
+namespace webrtc {
+
+namespace {
+
+class OldStyleEncodedFrame final : public AudioDecoder::EncodedAudioFrame {
+ public:
+  OldStyleEncodedFrame(AudioDecoder* decoder, rtc::Buffer&& payload)
+      : decoder_(decoder), payload_(std::move(payload)) {}
+
+  size_t Duration() const override {
+    const int ret = decoder_->PacketDuration(payload_.data(), payload_.size());
+    return ret < 0 ? 0 : static_cast<size_t>(ret);
+  }
+
+  absl::optional<DecodeResult> Decode(
+      rtc::ArrayView<int16_t> decoded) const override {
+    auto speech_type = AudioDecoder::kSpeech;
+    const int ret = decoder_->Decode(
+        payload_.data(), payload_.size(), decoder_->SampleRateHz(),
+        decoded.size() * sizeof(int16_t), decoded.data(), &speech_type);
+    return ret < 0 ? absl::nullopt
+                   : absl::optional<DecodeResult>(
+                         {static_cast<size_t>(ret), speech_type});
+  }
+
+ private:
+  AudioDecoder* const decoder_;
+  const rtc::Buffer payload_;
+};
+
+}  // namespace
+
+bool AudioDecoder::EncodedAudioFrame::IsDtxPacket() const {
+  return false;
+}
+
+AudioDecoder::ParseResult::ParseResult() = default;
+AudioDecoder::ParseResult::ParseResult(ParseResult&& b) = default;
+AudioDecoder::ParseResult::ParseResult(uint32_t timestamp,
+                                       int priority,
+                                       std::unique_ptr<EncodedAudioFrame> frame)
+    : timestamp(timestamp), priority(priority), frame(std::move(frame)) {
+  RTC_DCHECK_GE(priority, 0);
+}
+
+AudioDecoder::ParseResult::~ParseResult() = default;
+
+AudioDecoder::ParseResult& AudioDecoder::ParseResult::operator=(
+    ParseResult&& b) = default;
+
+std::vector<AudioDecoder::ParseResult> AudioDecoder::ParsePayload(
+    rtc::Buffer&& payload,
+    uint32_t timestamp) {
+  std::vector<ParseResult> results;
+  std::unique_ptr<EncodedAudioFrame> frame(
+      new OldStyleEncodedFrame(this, std::move(payload)));
+  results.emplace_back(timestamp, 0, std::move(frame));
+  return results;
+}
+
+int AudioDecoder::Decode(const uint8_t* encoded,
+                         size_t encoded_len,
+                         int sample_rate_hz,
+                         size_t max_decoded_bytes,
+                         int16_t* decoded,
+                         SpeechType* speech_type) {
+  TRACE_EVENT0("webrtc", "AudioDecoder::Decode");
+  rtc::MsanCheckInitialized(rtc::MakeArrayView(encoded, encoded_len));
+  int duration = PacketDuration(encoded, encoded_len);
+  if (duration >= 0 &&
+      duration * Channels() * sizeof(int16_t) > max_decoded_bytes) {
+    return -1;
+  }
+  return DecodeInternal(encoded, encoded_len, sample_rate_hz, decoded,
+                        speech_type);
+}
+
+int AudioDecoder::DecodeRedundant(const uint8_t* encoded,
+                                  size_t encoded_len,
+                                  int sample_rate_hz,
+                                  size_t max_decoded_bytes,
+                                  int16_t* decoded,
+                                  SpeechType* speech_type) {
+  TRACE_EVENT0("webrtc", "AudioDecoder::DecodeRedundant");
+  rtc::MsanCheckInitialized(rtc::MakeArrayView(encoded, encoded_len));
+  int duration = PacketDurationRedundant(encoded, encoded_len);
+  if (duration >= 0 &&
+      duration * Channels() * sizeof(int16_t) > max_decoded_bytes) {
+    return -1;
+  }
+  return DecodeRedundantInternal(encoded, encoded_len, sample_rate_hz, decoded,
+                                 speech_type);
+}
+
+int AudioDecoder::DecodeRedundantInternal(const uint8_t* encoded,
+                                          size_t encoded_len,
+                                          int sample_rate_hz,
+                                          int16_t* decoded,
+                                          SpeechType* speech_type) {
+  return DecodeInternal(encoded, encoded_len, sample_rate_hz, decoded,
+                        speech_type);
+}
+
+bool AudioDecoder::HasDecodePlc() const {
+  return false;
+}
+
+size_t AudioDecoder::DecodePlc(size_t num_frames, int16_t* decoded) {
+  return 0;
+}
+
+// TODO(bugs.webrtc.org/9676): Remove default implementation.
+void AudioDecoder::GeneratePlc(size_t /*requested_samples_per_channel*/,
+                               rtc::BufferT<int16_t>* /*concealment_audio*/) {}
+
+int AudioDecoder::ErrorCode() {
+  return 0;
+}
+
+int AudioDecoder::PacketDuration(const uint8_t* encoded,
+                                 size_t encoded_len) const {
+  return kNotImplemented;
+}
+
+int AudioDecoder::PacketDurationRedundant(const uint8_t* encoded,
+                                          size_t encoded_len) const {
+  return kNotImplemented;
+}
+
+bool AudioDecoder::PacketHasFec(const uint8_t* encoded,
+                                size_t encoded_len) const {
+  return false;
+}
+
+AudioDecoder::SpeechType AudioDecoder::ConvertSpeechType(int16_t type) {
+  switch (type) {
+    case 0:  // TODO(hlundin): Both iSAC and Opus return 0 for speech.
+    case 1:
+      return kSpeech;
+    case 2:
+      return kComfortNoise;
+    default:
+      assert(false);
+      return kSpeech;
+  }
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/audio_codecs/audio_decoder.h b/webrtc/api/audio_codecs/audio_decoder.h
new file mode 100644
index 0000000..557ffe2
--- /dev/null
+++ b/webrtc/api/audio_codecs/audio_decoder.h
@@ -0,0 +1,193 @@
+/*
+ *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_AUDIO_CODECS_AUDIO_DECODER_H_
+#define API_AUDIO_CODECS_AUDIO_DECODER_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+#include <vector>
+
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "rtc_base/buffer.h"
+#include "rtc_base/constructor_magic.h"
+
+namespace webrtc {
+
+class AudioDecoder {
+ public:
+  enum SpeechType {
+    kSpeech = 1,
+    kComfortNoise = 2,
+  };
+
+  // Used by PacketDuration below. Save the value -1 for errors.
+  enum { kNotImplemented = -2 };
+
+  AudioDecoder() = default;
+  virtual ~AudioDecoder() = default;
+
+  class EncodedAudioFrame {
+   public:
+    struct DecodeResult {
+      size_t num_decoded_samples;
+      SpeechType speech_type;
+    };
+
+    virtual ~EncodedAudioFrame() = default;
+
+    // Returns the duration in samples-per-channel of this audio frame.
+    // If no duration can be ascertained, returns zero.
+    virtual size_t Duration() const = 0;
+
+    // Returns true if this packet contains DTX.
+    virtual bool IsDtxPacket() const;
+
+    // Decodes this frame of audio and writes the result in |decoded|.
+    // |decoded| must be large enough to store as many samples as indicated by a
+    // call to Duration() . On success, returns an absl::optional containing the
+    // total number of samples across all channels, as well as whether the
+    // decoder produced comfort noise or speech. On failure, returns an empty
+    // absl::optional. Decode may be called at most once per frame object.
+    virtual absl::optional<DecodeResult> Decode(
+        rtc::ArrayView<int16_t> decoded) const = 0;
+  };
+
+  struct ParseResult {
+    ParseResult();
+    ParseResult(uint32_t timestamp,
+                int priority,
+                std::unique_ptr<EncodedAudioFrame> frame);
+    ParseResult(ParseResult&& b);
+    ~ParseResult();
+
+    ParseResult& operator=(ParseResult&& b);
+
+    // The timestamp of the frame is in samples per channel.
+    uint32_t timestamp;
+    // The relative priority of the frame compared to other frames of the same
+    // payload and the same timeframe. A higher value means a lower priority.
+    // The highest priority is zero - negative values are not allowed.
+    int priority;
+    std::unique_ptr<EncodedAudioFrame> frame;
+  };
+
+  // Let the decoder parse this payload and prepare zero or more decodable
+  // frames. Each frame must be between 10 ms and 120 ms long. The caller must
+  // ensure that the AudioDecoder object outlives any frame objects returned by
+  // this call. The decoder is free to swap or move the data from the |payload|
+  // buffer. |timestamp| is the input timestamp, in samples, corresponding to
+  // the start of the payload.
+  virtual std::vector<ParseResult> ParsePayload(rtc::Buffer&& payload,
+                                                uint32_t timestamp);
+
+  // TODO(bugs.webrtc.org/10098): The Decode and DecodeRedundant methods are
+  // obsolete; callers should call ParsePayload instead. For now, subclasses
+  // must still implement DecodeInternal.
+
+  // Decodes |encode_len| bytes from |encoded| and writes the result in
+  // |decoded|. The maximum bytes allowed to be written into |decoded| is
+  // |max_decoded_bytes|. Returns the total number of samples across all
+  // channels. If the decoder produced comfort noise, |speech_type|
+  // is set to kComfortNoise, otherwise it is kSpeech. The desired output
+  // sample rate is provided in |sample_rate_hz|, which must be valid for the
+  // codec at hand.
+  int Decode(const uint8_t* encoded,
+             size_t encoded_len,
+             int sample_rate_hz,
+             size_t max_decoded_bytes,
+             int16_t* decoded,
+             SpeechType* speech_type);
+
+  // Same as Decode(), but interfaces to the decoders redundant decode function.
+  // The default implementation simply calls the regular Decode() method.
+  int DecodeRedundant(const uint8_t* encoded,
+                      size_t encoded_len,
+                      int sample_rate_hz,
+                      size_t max_decoded_bytes,
+                      int16_t* decoded,
+                      SpeechType* speech_type);
+
+  // Indicates if the decoder implements the DecodePlc method.
+  virtual bool HasDecodePlc() const;
+
+  // Calls the packet-loss concealment of the decoder to update the state after
+  // one or several lost packets. The caller has to make sure that the
+  // memory allocated in |decoded| should accommodate |num_frames| frames.
+  virtual size_t DecodePlc(size_t num_frames, int16_t* decoded);
+
+  // Asks the decoder to generate packet-loss concealment and append it to the
+  // end of |concealment_audio|. The concealment audio should be in
+  // channel-interleaved format, with as many channels as the last decoded
+  // packet produced. The implementation must produce at least
+  // requested_samples_per_channel, or nothing at all. This is a signal to the
+  // caller to conceal the loss with other means. If the implementation provides
+  // concealment samples, it is also responsible for "stitching" it together
+  // with the decoded audio on either side of the concealment.
+  // Note: The default implementation of GeneratePlc will be deleted soon. All
+  // implementations must provide their own, which can be a simple as a no-op.
+  // TODO(bugs.webrtc.org/9676): Remove default impementation.
+  virtual void GeneratePlc(size_t requested_samples_per_channel,
+                           rtc::BufferT<int16_t>* concealment_audio);
+
+  // Resets the decoder state (empty buffers etc.).
+  virtual void Reset() = 0;
+
+  // Returns the last error code from the decoder.
+  virtual int ErrorCode();
+
+  // Returns the duration in samples-per-channel of the payload in |encoded|
+  // which is |encoded_len| bytes long. Returns kNotImplemented if no duration
+  // estimate is available, or -1 in case of an error.
+  virtual int PacketDuration(const uint8_t* encoded, size_t encoded_len) const;
+
+  // Returns the duration in samples-per-channel of the redandant payload in
+  // |encoded| which is |encoded_len| bytes long. Returns kNotImplemented if no
+  // duration estimate is available, or -1 in case of an error.
+  virtual int PacketDurationRedundant(const uint8_t* encoded,
+                                      size_t encoded_len) const;
+
+  // Detects whether a packet has forward error correction. The packet is
+  // comprised of the samples in |encoded| which is |encoded_len| bytes long.
+  // Returns true if the packet has FEC and false otherwise.
+  virtual bool PacketHasFec(const uint8_t* encoded, size_t encoded_len) const;
+
+  // Returns the actual sample rate of the decoder's output. This value may not
+  // change during the lifetime of the decoder.
+  virtual int SampleRateHz() const = 0;
+
+  // The number of channels in the decoder's output. This value may not change
+  // during the lifetime of the decoder.
+  virtual size_t Channels() const = 0;
+
+ protected:
+  static SpeechType ConvertSpeechType(int16_t type);
+
+  virtual int DecodeInternal(const uint8_t* encoded,
+                             size_t encoded_len,
+                             int sample_rate_hz,
+                             int16_t* decoded,
+                             SpeechType* speech_type) = 0;
+
+  virtual int DecodeRedundantInternal(const uint8_t* encoded,
+                                      size_t encoded_len,
+                                      int sample_rate_hz,
+                                      int16_t* decoded,
+                                      SpeechType* speech_type);
+
+ private:
+  RTC_DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
+};
+
+}  // namespace webrtc
+#endif  // API_AUDIO_CODECS_AUDIO_DECODER_H_
diff --git a/webrtc/api/audio_codecs/audio_encoder.cc b/webrtc/api/audio_codecs/audio_encoder.cc
new file mode 100644
index 0000000..cd4d200
--- /dev/null
+++ b/webrtc/api/audio_codecs/audio_encoder.cc
@@ -0,0 +1,113 @@
+/*
+ *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/audio_codecs/audio_encoder.h"
+
+#include "rtc_base/checks.h"
+#include "rtc_base/trace_event.h"
+
+namespace webrtc {
+
+ANAStats::ANAStats() = default;
+ANAStats::~ANAStats() = default;
+ANAStats::ANAStats(const ANAStats&) = default;
+
+AudioEncoder::EncodedInfo::EncodedInfo() = default;
+AudioEncoder::EncodedInfo::EncodedInfo(const EncodedInfo&) = default;
+AudioEncoder::EncodedInfo::EncodedInfo(EncodedInfo&&) = default;
+AudioEncoder::EncodedInfo::~EncodedInfo() = default;
+AudioEncoder::EncodedInfo& AudioEncoder::EncodedInfo::operator=(
+    const EncodedInfo&) = default;
+AudioEncoder::EncodedInfo& AudioEncoder::EncodedInfo::operator=(EncodedInfo&&) =
+    default;
+
+int AudioEncoder::RtpTimestampRateHz() const {
+  return SampleRateHz();
+}
+
+AudioEncoder::EncodedInfo AudioEncoder::Encode(
+    uint32_t rtp_timestamp,
+    rtc::ArrayView<const int16_t> audio,
+    rtc::Buffer* encoded) {
+  TRACE_EVENT0("webrtc", "AudioEncoder::Encode");
+  RTC_CHECK_EQ(audio.size(),
+               static_cast<size_t>(NumChannels() * SampleRateHz() / 100));
+
+  const size_t old_size = encoded->size();
+  EncodedInfo info = EncodeImpl(rtp_timestamp, audio, encoded);
+  RTC_CHECK_EQ(encoded->size() - old_size, info.encoded_bytes);
+  return info;
+}
+
+bool AudioEncoder::SetFec(bool enable) {
+  return !enable;
+}
+
+bool AudioEncoder::SetDtx(bool enable) {
+  return !enable;
+}
+
+bool AudioEncoder::GetDtx() const {
+  return false;
+}
+
+bool AudioEncoder::SetApplication(Application application) {
+  return false;
+}
+
+void AudioEncoder::SetMaxPlaybackRate(int frequency_hz) {}
+
+void AudioEncoder::SetTargetBitrate(int target_bps) {}
+
+rtc::ArrayView<std::unique_ptr<AudioEncoder>>
+AudioEncoder::ReclaimContainedEncoders() {
+  return nullptr;
+}
+
+bool AudioEncoder::EnableAudioNetworkAdaptor(const std::string& config_string,
+                                             RtcEventLog* event_log) {
+  return false;
+}
+
+void AudioEncoder::DisableAudioNetworkAdaptor() {}
+
+void AudioEncoder::OnReceivedUplinkPacketLossFraction(
+    float uplink_packet_loss_fraction) {}
+
+void AudioEncoder::OnReceivedUplinkRecoverablePacketLossFraction(
+    float uplink_recoverable_packet_loss_fraction) {
+  RTC_NOTREACHED();
+}
+
+void AudioEncoder::OnReceivedTargetAudioBitrate(int target_audio_bitrate_bps) {
+  OnReceivedUplinkBandwidth(target_audio_bitrate_bps, absl::nullopt);
+}
+
+void AudioEncoder::OnReceivedUplinkBandwidth(
+    int target_audio_bitrate_bps,
+    absl::optional<int64_t> bwe_period_ms) {}
+
+void AudioEncoder::OnReceivedUplinkAllocation(BitrateAllocationUpdate update) {
+  OnReceivedUplinkBandwidth(update.target_bitrate.bps(),
+                            update.bwe_period.ms());
+}
+
+void AudioEncoder::OnReceivedRtt(int rtt_ms) {}
+
+void AudioEncoder::OnReceivedOverhead(size_t overhead_bytes_per_packet) {}
+
+void AudioEncoder::SetReceiverFrameLengthRange(int min_frame_length_ms,
+                                               int max_frame_length_ms) {}
+
+ANAStats AudioEncoder::GetANAStats() const {
+  return ANAStats();
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/audio_codecs/audio_encoder.h b/webrtc/api/audio_codecs/audio_encoder.h
new file mode 100644
index 0000000..fd2d948
--- /dev/null
+++ b/webrtc/api/audio_codecs/audio_encoder.h
@@ -0,0 +1,257 @@
+/*
+ *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_AUDIO_CODECS_AUDIO_ENCODER_H_
+#define API_AUDIO_CODECS_AUDIO_ENCODER_H_
+
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "api/call/bitrate_allocation.h"
+#include "api/units/time_delta.h"
+#include "rtc_base/buffer.h"
+#include "rtc_base/deprecation.h"
+
+namespace webrtc {
+
+class RtcEventLog;
+
+// Statistics related to Audio Network Adaptation.
+struct ANAStats {
+  ANAStats();
+  ANAStats(const ANAStats&);
+  ~ANAStats();
+  // Number of actions taken by the ANA bitrate controller since the start of
+  // the call. If this value is not set, it indicates that the bitrate
+  // controller is disabled.
+  absl::optional<uint32_t> bitrate_action_counter;
+  // Number of actions taken by the ANA channel controller since the start of
+  // the call. If this value is not set, it indicates that the channel
+  // controller is disabled.
+  absl::optional<uint32_t> channel_action_counter;
+  // Number of actions taken by the ANA DTX controller since the start of the
+  // call. If this value is not set, it indicates that the DTX controller is
+  // disabled.
+  absl::optional<uint32_t> dtx_action_counter;
+  // Number of actions taken by the ANA FEC controller since the start of the
+  // call. If this value is not set, it indicates that the FEC controller is
+  // disabled.
+  absl::optional<uint32_t> fec_action_counter;
+  // Number of times the ANA frame length controller decided to increase the
+  // frame length since the start of the call. If this value is not set, it
+  // indicates that the frame length controller is disabled.
+  absl::optional<uint32_t> frame_length_increase_counter;
+  // Number of times the ANA frame length controller decided to decrease the
+  // frame length since the start of the call. If this value is not set, it
+  // indicates that the frame length controller is disabled.
+  absl::optional<uint32_t> frame_length_decrease_counter;
+  // The uplink packet loss fractions as set by the ANA FEC controller. If this
+  // value is not set, it indicates that the ANA FEC controller is not active.
+  absl::optional<float> uplink_packet_loss_fraction;
+};
+
+// This is the interface class for encoders in AudioCoding module. Each codec
+// type must have an implementation of this class.
+class AudioEncoder {
+ public:
+  // Used for UMA logging of codec usage. The same codecs, with the
+  // same values, must be listed in
+  // src/tools/metrics/histograms/histograms.xml in chromium to log
+  // correct values.
+  enum class CodecType {
+    kOther = 0,  // Codec not specified, and/or not listed in this enum
+    kOpus = 1,
+    kIsac = 2,
+    kPcmA = 3,
+    kPcmU = 4,
+    kG722 = 5,
+    kIlbc = 6,
+
+    // Number of histogram bins in the UMA logging of codec types. The
+    // total number of different codecs that are logged cannot exceed this
+    // number.
+    kMaxLoggedAudioCodecTypes
+  };
+
+  struct EncodedInfoLeaf {
+    size_t encoded_bytes = 0;
+    uint32_t encoded_timestamp = 0;
+    int payload_type = 0;
+    bool send_even_if_empty = false;
+    bool speech = true;
+    CodecType encoder_type = CodecType::kOther;
+  };
+
+  // This is the main struct for auxiliary encoding information. Each encoded
+  // packet should be accompanied by one EncodedInfo struct, containing the
+  // total number of |encoded_bytes|, the |encoded_timestamp| and the
+  // |payload_type|. If the packet contains redundant encodings, the |redundant|
+  // vector will be populated with EncodedInfoLeaf structs. Each struct in the
+  // vector represents one encoding; the order of structs in the vector is the
+  // same as the order in which the actual payloads are written to the byte
+  // stream. When EncoderInfoLeaf structs are present in the vector, the main
+  // struct's |encoded_bytes| will be the sum of all the |encoded_bytes| in the
+  // vector.
+  struct EncodedInfo : public EncodedInfoLeaf {
+    EncodedInfo();
+    EncodedInfo(const EncodedInfo&);
+    EncodedInfo(EncodedInfo&&);
+    ~EncodedInfo();
+    EncodedInfo& operator=(const EncodedInfo&);
+    EncodedInfo& operator=(EncodedInfo&&);
+
+    std::vector<EncodedInfoLeaf> redundant;
+  };
+
+  virtual ~AudioEncoder() = default;
+
+  // Returns the input sample rate in Hz and the number of input channels.
+  // These are constants set at instantiation time.
+  virtual int SampleRateHz() const = 0;
+  virtual size_t NumChannels() const = 0;
+
+  // Returns the rate at which the RTP timestamps are updated. The default
+  // implementation returns SampleRateHz().
+  virtual int RtpTimestampRateHz() const;
+
+  // Returns the number of 10 ms frames the encoder will put in the next
+  // packet. This value may only change when Encode() outputs a packet; i.e.,
+  // the encoder may vary the number of 10 ms frames from packet to packet, but
+  // it must decide the length of the next packet no later than when outputting
+  // the preceding packet.
+  virtual size_t Num10MsFramesInNextPacket() const = 0;
+
+  // Returns the maximum value that can be returned by
+  // Num10MsFramesInNextPacket().
+  virtual size_t Max10MsFramesInAPacket() const = 0;
+
+  // Returns the current target bitrate in bits/s. The value -1 means that the
+  // codec adapts the target automatically, and a current target cannot be
+  // provided.
+  virtual int GetTargetBitrate() const = 0;
+
+  // Accepts one 10 ms block of input audio (i.e., SampleRateHz() / 100 *
+  // NumChannels() samples). Multi-channel audio must be sample-interleaved.
+  // The encoder appends zero or more bytes of output to |encoded| and returns
+  // additional encoding information.  Encode() checks some preconditions, calls
+  // EncodeImpl() which does the actual work, and then checks some
+  // postconditions.
+  EncodedInfo Encode(uint32_t rtp_timestamp,
+                     rtc::ArrayView<const int16_t> audio,
+                     rtc::Buffer* encoded);
+
+  // Resets the encoder to its starting state, discarding any input that has
+  // been fed to the encoder but not yet emitted in a packet.
+  virtual void Reset() = 0;
+
+  // Enables or disables codec-internal FEC (forward error correction). Returns
+  // true if the codec was able to comply. The default implementation returns
+  // true when asked to disable FEC and false when asked to enable it (meaning
+  // that FEC isn't supported).
+  virtual bool SetFec(bool enable);
+
+  // Enables or disables codec-internal VAD/DTX. Returns true if the codec was
+  // able to comply. The default implementation returns true when asked to
+  // disable DTX and false when asked to enable it (meaning that DTX isn't
+  // supported).
+  virtual bool SetDtx(bool enable);
+
+  // Returns the status of codec-internal DTX. The default implementation always
+  // returns false.
+  virtual bool GetDtx() const;
+
+  // Sets the application mode. Returns true if the codec was able to comply.
+  // The default implementation just returns false.
+  enum class Application { kSpeech, kAudio };
+  virtual bool SetApplication(Application application);
+
+  // Tells the encoder about the highest sample rate the decoder is expected to
+  // use when decoding the bitstream. The encoder would typically use this
+  // information to adjust the quality of the encoding. The default
+  // implementation does nothing.
+  virtual void SetMaxPlaybackRate(int frequency_hz);
+
+  // This is to be deprecated. Please use |OnReceivedTargetAudioBitrate|
+  // instead.
+  // Tells the encoder what average bitrate we'd like it to produce. The
+  // encoder is free to adjust or disregard the given bitrate (the default
+  // implementation does the latter).
+  RTC_DEPRECATED virtual void SetTargetBitrate(int target_bps);
+
+  // Causes this encoder to let go of any other encoders it contains, and
+  // returns a pointer to an array where they are stored (which is required to
+  // live as long as this encoder). Unless the returned array is empty, you may
+  // not call any methods on this encoder afterwards, except for the
+  // destructor. The default implementation just returns an empty array.
+  // NOTE: This method is subject to change. Do not call or override it.
+  virtual rtc::ArrayView<std::unique_ptr<AudioEncoder>>
+  ReclaimContainedEncoders();
+
+  // Enables audio network adaptor. Returns true if successful.
+  virtual bool EnableAudioNetworkAdaptor(const std::string& config_string,
+                                         RtcEventLog* event_log);
+
+  // Disables audio network adaptor.
+  virtual void DisableAudioNetworkAdaptor();
+
+  // Provides uplink packet loss fraction to this encoder to allow it to adapt.
+  // |uplink_packet_loss_fraction| is in the range [0.0, 1.0].
+  virtual void OnReceivedUplinkPacketLossFraction(
+      float uplink_packet_loss_fraction);
+
+  RTC_DEPRECATED virtual void OnReceivedUplinkRecoverablePacketLossFraction(
+      float uplink_recoverable_packet_loss_fraction);
+
+  // Provides target audio bitrate to this encoder to allow it to adapt.
+  virtual void OnReceivedTargetAudioBitrate(int target_bps);
+
+  // Provides target audio bitrate and corresponding probing interval of
+  // the bandwidth estimator to this encoder to allow it to adapt.
+  virtual void OnReceivedUplinkBandwidth(int target_audio_bitrate_bps,
+                                         absl::optional<int64_t> bwe_period_ms);
+
+  // Provides target audio bitrate and corresponding probing interval of
+  // the bandwidth estimator to this encoder to allow it to adapt.
+  virtual void OnReceivedUplinkAllocation(BitrateAllocationUpdate update);
+
+  // Provides RTT to this encoder to allow it to adapt.
+  virtual void OnReceivedRtt(int rtt_ms);
+
+  // Provides overhead to this encoder to adapt. The overhead is the number of
+  // bytes that will be added to each packet the encoder generates.
+  virtual void OnReceivedOverhead(size_t overhead_bytes_per_packet);
+
+  // To allow encoder to adapt its frame length, it must be provided the frame
+  // length range that receivers can accept.
+  virtual void SetReceiverFrameLengthRange(int min_frame_length_ms,
+                                           int max_frame_length_ms);
+
+  // Get statistics related to audio network adaptation.
+  virtual ANAStats GetANAStats() const;
+
+  // The range of frame lengths that are supported or nullopt if there's no sch
+  // information. This is used to calculated the full bitrate range, including
+  // overhead.
+  virtual absl::optional<std::pair<TimeDelta, TimeDelta>> GetFrameLengthRange()
+      const = 0;
+
+ protected:
+  // Subclasses implement this to perform the actual encoding. Called by
+  // Encode().
+  virtual EncodedInfo EncodeImpl(uint32_t rtp_timestamp,
+                                 rtc::ArrayView<const int16_t> audio,
+                                 rtc::Buffer* encoded) = 0;
+};
+}  // namespace webrtc
+#endif  // API_AUDIO_CODECS_AUDIO_ENCODER_H_
diff --git a/webrtc/api/call/bitrate_allocation.h b/webrtc/api/call/bitrate_allocation.h
new file mode 100644
index 0000000..13c7f74
--- /dev/null
+++ b/webrtc/api/call/bitrate_allocation.h
@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_CALL_BITRATE_ALLOCATION_H_
+#define API_CALL_BITRATE_ALLOCATION_H_
+
+#include "api/units/data_rate.h"
+#include "api/units/time_delta.h"
+
+namespace webrtc {
+
+// BitrateAllocationUpdate provides information to allocated streams about their
+// bitrate allocation. It originates from the BitrateAllocater class and is
+// propagated from there.
+struct BitrateAllocationUpdate {
+  // The allocated target bitrate. Media streams should produce this amount of
+  // data. (Note that this may include packet overhead depending on
+  // configuration.)
+  DataRate target_bitrate = DataRate::Zero();
+  // The allocated part of the estimated link capacity. This is more stable than
+  // the target as it is based on the underlying link capacity estimate. This
+  // should be used to change encoder configuration when the cost of change is
+  // high.
+  DataRate stable_target_bitrate = DataRate::Zero();
+  // Predicted packet loss ratio.
+  double packet_loss_ratio = 0;
+  // Predicted round trip time.
+  TimeDelta round_trip_time = TimeDelta::PlusInfinity();
+  // |bwe_period| is deprecated, use |stable_target_bitrate| allocation instead.
+  TimeDelta bwe_period = TimeDelta::PlusInfinity();
+  // Congestion window pushback bitrate reduction fraction. Used in
+  // VideoStreamEncoder to reduce the bitrate by the given fraction
+  // by dropping frames.
+  double cwnd_reduce_ratio = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // API_CALL_BITRATE_ALLOCATION_H_
diff --git a/webrtc/api/function_view.h b/webrtc/api/function_view.h
new file mode 100644
index 0000000..5ae1bd6
--- /dev/null
+++ b/webrtc/api/function_view.h
@@ -0,0 +1,130 @@
+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_FUNCTION_VIEW_H_
+#define API_FUNCTION_VIEW_H_
+
+#include <type_traits>
+#include <utility>
+
+#include "rtc_base/checks.h"
+
+// Just like std::function, FunctionView will wrap any callable and hide its
+// actual type, exposing only its signature. But unlike std::function,
+// FunctionView doesn't own its callable---it just points to it. Thus, it's a
+// good choice mainly as a function argument when the callable argument will
+// not be called again once the function has returned.
+//
+// Its constructors are implicit, so that callers won't have to convert lambdas
+// and other callables to FunctionView<Blah(Blah, Blah)> explicitly. This is
+// safe because FunctionView is only a reference to the real callable.
+//
+// Example use:
+//
+//   void SomeFunction(rtc::FunctionView<int(int)> index_transform);
+//   ...
+//   SomeFunction([](int i) { return 2 * i + 1; });
+//
+// Note: FunctionView is tiny (essentially just two pointers) and trivially
+// copyable, so it's probably cheaper to pass it by value than by const
+// reference.
+
+namespace rtc {
+
+template <typename T>
+class FunctionView;  // Undefined.
+
+template <typename RetT, typename... ArgT>
+class FunctionView<RetT(ArgT...)> final {
+ public:
+  // Constructor for lambdas and other callables; it accepts every type of
+  // argument except those noted in its enable_if call.
+  template <
+      typename F,
+      typename std::enable_if<
+          // Not for function pointers; we have another constructor for that
+          // below.
+          !std::is_function<typename std::remove_pointer<
+              typename std::remove_reference<F>::type>::type>::value &&
+
+          // Not for nullptr; we have another constructor for that below.
+          !std::is_same<std::nullptr_t,
+                        typename std::remove_cv<F>::type>::value &&
+
+          // Not for FunctionView objects; we have another constructor for that
+          // (the implicitly declared copy constructor).
+          !std::is_same<FunctionView,
+                        typename std::remove_cv<typename std::remove_reference<
+                            F>::type>::type>::value>::type* = nullptr>
+  FunctionView(F&& f)
+      : call_(CallVoidPtr<typename std::remove_reference<F>::type>) {
+    f_.void_ptr = &f;
+  }
+
+  // Constructor that accepts function pointers. If the argument is null, the
+  // result is an empty FunctionView.
+  template <
+      typename F,
+      typename std::enable_if<std::is_function<typename std::remove_pointer<
+          typename std::remove_reference<F>::type>::type>::value>::type* =
+          nullptr>
+  FunctionView(F&& f)
+      : call_(f ? CallFunPtr<typename std::remove_pointer<F>::type> : nullptr) {
+    f_.fun_ptr = reinterpret_cast<void (*)()>(f);
+  }
+
+  // Constructor that accepts nullptr. It creates an empty FunctionView.
+  template <typename F,
+            typename std::enable_if<std::is_same<
+                std::nullptr_t,
+                typename std::remove_cv<F>::type>::value>::type* = nullptr>
+  FunctionView(F&& f) : call_(nullptr) {}
+
+  // Default constructor. Creates an empty FunctionView.
+  FunctionView() : call_(nullptr) {}
+
+  RetT operator()(ArgT... args) const {
+    RTC_DCHECK(call_);
+    return call_(f_, std::forward<ArgT>(args)...);
+  }
+
+  // Returns true if we have a function, false if we don't (i.e., we're null).
+  explicit operator bool() const { return !!call_; }
+
+ private:
+  union VoidUnion {
+    void* void_ptr;
+    void (*fun_ptr)();
+  };
+
+  template <typename F>
+  static RetT CallVoidPtr(VoidUnion vu, ArgT... args) {
+    return (*static_cast<F*>(vu.void_ptr))(std::forward<ArgT>(args)...);
+  }
+  template <typename F>
+  static RetT CallFunPtr(VoidUnion vu, ArgT... args) {
+    return (reinterpret_cast<typename std::add_pointer<F>::type>(vu.fun_ptr))(
+        std::forward<ArgT>(args)...);
+  }
+
+  // A pointer to the callable thing, with type information erased. It's a
+  // union because we have to use separate types depending on if the callable
+  // thing is a function pointer or something else.
+  VoidUnion f_;
+
+  // Pointer to a dispatch function that knows the type of the callable thing
+  // that's stored in f_, and how to call it. A FunctionView object is empty
+  // (null) iff call_ is null.
+  RetT (*call_)(VoidUnion, ArgT...);
+};
+
+}  // namespace rtc
+
+#endif  // API_FUNCTION_VIEW_H_
diff --git a/webrtc/api/meson.build b/webrtc/api/meson.build
new file mode 100644
index 0000000..1d26709
--- /dev/null
+++ b/webrtc/api/meson.build
@@ -0,0 +1,46 @@
+api_sources = [
+  'audio/audio_frame.cc',
+  'audio/channel_layout.cc',
+  'audio/echo_canceller3_config.cc',
+  'audio_codecs/audio_decoder.cc',
+  'audio_codecs/audio_encoder.cc',
+  'rtp_headers.cc',
+  'rtp_packet_info.cc',
+  'task_queue/task_queue_base.cc',
+  'units/data_rate.cc',
+  'units/data_size.cc',
+  'units/frequency.cc',
+  'units/time_delta.cc',
+  'units/timestamp.cc',
+  'video/color_space.cc',
+  'video/hdr_metadata.cc',
+  'video/video_content_type.cc',
+  'video/video_timing.cc',
+]
+
+api_headers = [
+  ['', 'array_view.h'],
+  ['', 'scoped_refptr.h'],
+  ['audio', 'echo_canceller3_config.h'],
+  ['audio', 'echo_control.h'],
+]
+
+foreach h : api_headers
+  install_headers(
+    join_paths(h[0], h[1]),
+    subdir: join_paths('webrtc_audio_processing', 'api', h[0])
+  )
+endforeach
+
+
+libapi = static_library('libapi',
+    api_sources,
+    dependencies: common_deps,
+    include_directories: webrtc_inc,
+    cpp_args : common_cxxflags
+)
+
+api_dep = declare_dependency(
+    link_with: libapi
+)
+
diff --git a/webrtc/api/ref_counted_base.h b/webrtc/api/ref_counted_base.h
new file mode 100644
index 0000000..a1761db
--- /dev/null
+++ b/webrtc/api/ref_counted_base.h
@@ -0,0 +1,43 @@
+/*
+ *  Copyright 2017 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_REF_COUNTED_BASE_H_
+#define API_REF_COUNTED_BASE_H_
+
+#include "rtc_base/constructor_magic.h"
+#include "rtc_base/ref_count.h"
+#include "rtc_base/ref_counter.h"
+
+namespace rtc {
+
+class RefCountedBase {
+ public:
+  RefCountedBase() = default;
+
+  void AddRef() const { ref_count_.IncRef(); }
+  RefCountReleaseStatus Release() const {
+    const auto status = ref_count_.DecRef();
+    if (status == RefCountReleaseStatus::kDroppedLastRef) {
+      delete this;
+    }
+    return status;
+  }
+
+ protected:
+  virtual ~RefCountedBase() = default;
+
+ private:
+  mutable webrtc::webrtc_impl::RefCounter ref_count_{0};
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(RefCountedBase);
+};
+
+}  // namespace rtc
+
+#endif  // API_REF_COUNTED_BASE_H_
diff --git a/webrtc/api/rtp_headers.cc b/webrtc/api/rtp_headers.cc
new file mode 100644
index 0000000..e0ad9eb
--- /dev/null
+++ b/webrtc/api/rtp_headers.cc
@@ -0,0 +1,54 @@
+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/rtp_headers.h"
+
+namespace webrtc {
+
+RTPHeaderExtension::RTPHeaderExtension()
+    : hasTransmissionTimeOffset(false),
+      transmissionTimeOffset(0),
+      hasAbsoluteSendTime(false),
+      absoluteSendTime(0),
+      hasTransportSequenceNumber(false),
+      transportSequenceNumber(0),
+      hasAudioLevel(false),
+      voiceActivity(false),
+      audioLevel(0),
+      hasVideoRotation(false),
+      videoRotation(kVideoRotation_0),
+      hasVideoContentType(false),
+      videoContentType(VideoContentType::UNSPECIFIED),
+      has_video_timing(false) {}
+
+RTPHeaderExtension::RTPHeaderExtension(const RTPHeaderExtension& other) =
+    default;
+
+RTPHeaderExtension& RTPHeaderExtension::operator=(
+    const RTPHeaderExtension& other) = default;
+
+RTPHeader::RTPHeader()
+    : markerBit(false),
+      payloadType(0),
+      sequenceNumber(0),
+      timestamp(0),
+      ssrc(0),
+      numCSRCs(0),
+      arrOfCSRCs(),
+      paddingLength(0),
+      headerLength(0),
+      payload_type_frequency(0),
+      extension() {}
+
+RTPHeader::RTPHeader(const RTPHeader& other) = default;
+
+RTPHeader& RTPHeader::operator=(const RTPHeader& other) = default;
+
+}  // namespace webrtc
diff --git a/webrtc/api/rtp_headers.h b/webrtc/api/rtp_headers.h
new file mode 100644
index 0000000..b9a97c8
--- /dev/null
+++ b/webrtc/api/rtp_headers.h
@@ -0,0 +1,190 @@
+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_RTP_HEADERS_H_
+#define API_RTP_HEADERS_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <string>
+
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "api/units/timestamp.h"
+#include "api/video/color_space.h"
+#include "api/video/video_content_type.h"
+#include "api/video/video_rotation.h"
+#include "api/video/video_timing.h"
+
+namespace webrtc {
+
+struct FeedbackRequest {
+  // Determines whether the recv delta as specified in
+  // https://tools.ietf.org/html/draft-holmer-rmcat-transport-wide-cc-extensions-01
+  // should be included.
+  bool include_timestamps;
+  // Include feedback of received packets in the range [sequence_number -
+  // sequence_count + 1, sequence_number]. That is, no feedback will be sent if
+  // sequence_count is zero.
+  int sequence_count;
+};
+
+// The Absolute Capture Time extension is used to stamp RTP packets with a NTP
+// timestamp showing when the first audio or video frame in a packet was
+// originally captured. The intent of this extension is to provide a way to
+// accomplish audio-to-video synchronization when RTCP-terminating intermediate
+// systems (e.g. mixers) are involved. See:
+// http://www.webrtc.org/experiments/rtp-hdrext/abs-capture-time
+struct AbsoluteCaptureTime {
+  // Absolute capture timestamp is the NTP timestamp of when the first frame in
+  // a packet was originally captured. This timestamp MUST be based on the same
+  // clock as the clock used to generate NTP timestamps for RTCP sender reports
+  // on the capture system.
+  //
+  // It’s not always possible to do an NTP clock readout at the exact moment of
+  // when a media frame is captured. A capture system MAY postpone the readout
+  // until a more convenient time. A capture system SHOULD have known delays
+  // (e.g. from hardware buffers) subtracted from the readout to make the final
+  // timestamp as close to the actual capture time as possible.
+  //
+  // This field is encoded as a 64-bit unsigned fixed-point number with the high
+  // 32 bits for the timestamp in seconds and low 32 bits for the fractional
+  // part. This is also known as the UQ32.32 format and is what the RTP
+  // specification defines as the canonical format to represent NTP timestamps.
+  uint64_t absolute_capture_timestamp;
+
+  // Estimated capture clock offset is the sender’s estimate of the offset
+  // between its own NTP clock and the capture system’s NTP clock. The sender is
+  // here defined as the system that owns the NTP clock used to generate the NTP
+  // timestamps for the RTCP sender reports on this stream. The sender system is
+  // typically either the capture system or a mixer.
+  //
+  // This field is encoded as a 64-bit two’s complement signed fixed-point
+  // number with the high 32 bits for the seconds and low 32 bits for the
+  // fractional part. It’s intended to make it easy for a receiver, that knows
+  // how to estimate the sender system’s NTP clock, to also estimate the capture
+  // system’s NTP clock:
+  //
+  //   Capture NTP Clock = Sender NTP Clock + Capture Clock Offset
+  absl::optional<int64_t> estimated_capture_clock_offset;
+};
+
+inline bool operator==(const AbsoluteCaptureTime& lhs,
+                       const AbsoluteCaptureTime& rhs) {
+  return (lhs.absolute_capture_timestamp == rhs.absolute_capture_timestamp) &&
+         (lhs.estimated_capture_clock_offset ==
+          rhs.estimated_capture_clock_offset);
+}
+
+inline bool operator!=(const AbsoluteCaptureTime& lhs,
+                       const AbsoluteCaptureTime& rhs) {
+  return !(lhs == rhs);
+}
+
+struct RTPHeaderExtension {
+  RTPHeaderExtension();
+  RTPHeaderExtension(const RTPHeaderExtension& other);
+  RTPHeaderExtension& operator=(const RTPHeaderExtension& other);
+
+  static constexpr int kAbsSendTimeFraction = 18;
+
+  Timestamp GetAbsoluteSendTimestamp() const {
+    RTC_DCHECK(hasAbsoluteSendTime);
+    RTC_DCHECK(absoluteSendTime < (1ul << 24));
+    return Timestamp::Micros((absoluteSendTime * 1000000ll) /
+                             (1 << kAbsSendTimeFraction));
+  }
+
+  TimeDelta GetAbsoluteSendTimeDelta(uint32_t previous_sendtime) const {
+    RTC_DCHECK(hasAbsoluteSendTime);
+    RTC_DCHECK(absoluteSendTime < (1ul << 24));
+    RTC_DCHECK(previous_sendtime < (1ul << 24));
+    int32_t delta =
+        static_cast<int32_t>((absoluteSendTime - previous_sendtime) << 8) >> 8;
+    return TimeDelta::Micros((delta * 1000000ll) / (1 << kAbsSendTimeFraction));
+  }
+
+  bool hasTransmissionTimeOffset;
+  int32_t transmissionTimeOffset;
+  bool hasAbsoluteSendTime;
+  uint32_t absoluteSendTime;
+  absl::optional<AbsoluteCaptureTime> absolute_capture_time;
+  bool hasTransportSequenceNumber;
+  uint16_t transportSequenceNumber;
+  absl::optional<FeedbackRequest> feedback_request;
+
+  // Audio Level includes both level in dBov and voiced/unvoiced bit. See:
+  // https://tools.ietf.org/html/rfc6464#section-3
+  bool hasAudioLevel;
+  bool voiceActivity;
+  uint8_t audioLevel;
+
+  // For Coordination of Video Orientation. See
+  // http://www.etsi.org/deliver/etsi_ts/126100_126199/126114/12.07.00_60/
+  // ts_126114v120700p.pdf
+  bool hasVideoRotation;
+  VideoRotation videoRotation;
+
+  // TODO(ilnik): Refactor this and one above to be absl::optional() and remove
+  // a corresponding bool flag.
+  bool hasVideoContentType;
+  VideoContentType videoContentType;
+
+  bool has_video_timing;
+  VideoSendTiming video_timing;
+
+  VideoPlayoutDelay playout_delay;
+
+  // For identification of a stream when ssrc is not signaled. See
+  // https://tools.ietf.org/html/draft-ietf-avtext-rid-09
+  // TODO(danilchap): Update url from draft to release version.
+  std::string stream_id;
+  std::string repaired_stream_id;
+
+  // For identifying the media section used to interpret this RTP packet. See
+  // https://tools.ietf.org/html/draft-ietf-mmusic-sdp-bundle-negotiation-38
+  std::string mid;
+
+  absl::optional<ColorSpace> color_space;
+};
+
+enum { kRtpCsrcSize = 15 };  // RFC 3550 page 13
+
+struct RTPHeader {
+  RTPHeader();
+  RTPHeader(const RTPHeader& other);
+  RTPHeader& operator=(const RTPHeader& other);
+
+  bool markerBit;
+  uint8_t payloadType;
+  uint16_t sequenceNumber;
+  uint32_t timestamp;
+  uint32_t ssrc;
+  uint8_t numCSRCs;
+  uint32_t arrOfCSRCs[kRtpCsrcSize];
+  size_t paddingLength;
+  size_t headerLength;
+  int payload_type_frequency;
+  RTPHeaderExtension extension;
+};
+
+// RTCP mode to use. Compound mode is described by RFC 4585 and reduced-size
+// RTCP mode is described by RFC 5506.
+enum class RtcpMode { kOff, kCompound, kReducedSize };
+
+enum NetworkState {
+  kNetworkUp,
+  kNetworkDown,
+};
+
+}  // namespace webrtc
+
+#endif  // API_RTP_HEADERS_H_
diff --git a/webrtc/api/rtp_packet_info.cc b/webrtc/api/rtp_packet_info.cc
new file mode 100644
index 0000000..a9ebd9d
--- /dev/null
+++ b/webrtc/api/rtp_packet_info.cc
@@ -0,0 +1,60 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/rtp_packet_info.h"
+
+#include <algorithm>
+#include <utility>
+
+namespace webrtc {
+
+RtpPacketInfo::RtpPacketInfo()
+    : ssrc_(0), rtp_timestamp_(0), receive_time_ms_(-1) {}
+
+RtpPacketInfo::RtpPacketInfo(
+    uint32_t ssrc,
+    std::vector<uint32_t> csrcs,
+    uint32_t rtp_timestamp,
+    absl::optional<uint8_t> audio_level,
+    absl::optional<AbsoluteCaptureTime> absolute_capture_time,
+    int64_t receive_time_ms)
+    : ssrc_(ssrc),
+      csrcs_(std::move(csrcs)),
+      rtp_timestamp_(rtp_timestamp),
+      audio_level_(audio_level),
+      absolute_capture_time_(absolute_capture_time),
+      receive_time_ms_(receive_time_ms) {}
+
+RtpPacketInfo::RtpPacketInfo(const RTPHeader& rtp_header,
+                             int64_t receive_time_ms)
+    : ssrc_(rtp_header.ssrc),
+      rtp_timestamp_(rtp_header.timestamp),
+      receive_time_ms_(receive_time_ms) {
+  const auto& extension = rtp_header.extension;
+  const auto csrcs_count = std::min<size_t>(rtp_header.numCSRCs, kRtpCsrcSize);
+
+  csrcs_.assign(&rtp_header.arrOfCSRCs[0], &rtp_header.arrOfCSRCs[csrcs_count]);
+
+  if (extension.hasAudioLevel) {
+    audio_level_ = extension.audioLevel;
+  }
+
+  absolute_capture_time_ = extension.absolute_capture_time;
+}
+
+bool operator==(const RtpPacketInfo& lhs, const RtpPacketInfo& rhs) {
+  return (lhs.ssrc() == rhs.ssrc()) && (lhs.csrcs() == rhs.csrcs()) &&
+         (lhs.rtp_timestamp() == rhs.rtp_timestamp()) &&
+         (lhs.audio_level() == rhs.audio_level()) &&
+         (lhs.absolute_capture_time() == rhs.absolute_capture_time()) &&
+         (lhs.receive_time_ms() == rhs.receive_time_ms());
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/rtp_packet_info.h b/webrtc/api/rtp_packet_info.h
new file mode 100644
index 0000000..639ba32
--- /dev/null
+++ b/webrtc/api/rtp_packet_info.h
@@ -0,0 +1,97 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_RTP_PACKET_INFO_H_
+#define API_RTP_PACKET_INFO_H_
+
+#include <cstdint>
+#include <utility>
+#include <vector>
+
+#include "absl/types/optional.h"
+#include "api/rtp_headers.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+//
+// Structure to hold information about a received |RtpPacket|. It is primarily
+// used to carry per-packet information from when a packet is received until
+// the information is passed to |SourceTracker|.
+//
+class RTC_EXPORT RtpPacketInfo {
+ public:
+  RtpPacketInfo();
+
+  RtpPacketInfo(uint32_t ssrc,
+                std::vector<uint32_t> csrcs,
+                uint32_t rtp_timestamp,
+                absl::optional<uint8_t> audio_level,
+                absl::optional<AbsoluteCaptureTime> absolute_capture_time,
+                int64_t receive_time_ms);
+
+  RtpPacketInfo(const RTPHeader& rtp_header, int64_t receive_time_ms);
+
+  RtpPacketInfo(const RtpPacketInfo& other) = default;
+  RtpPacketInfo(RtpPacketInfo&& other) = default;
+  RtpPacketInfo& operator=(const RtpPacketInfo& other) = default;
+  RtpPacketInfo& operator=(RtpPacketInfo&& other) = default;
+
+  uint32_t ssrc() const { return ssrc_; }
+  void set_ssrc(uint32_t value) { ssrc_ = value; }
+
+  const std::vector<uint32_t>& csrcs() const { return csrcs_; }
+  void set_csrcs(std::vector<uint32_t> value) { csrcs_ = std::move(value); }
+
+  uint32_t rtp_timestamp() const { return rtp_timestamp_; }
+  void set_rtp_timestamp(uint32_t value) { rtp_timestamp_ = value; }
+
+  absl::optional<uint8_t> audio_level() const { return audio_level_; }
+  void set_audio_level(absl::optional<uint8_t> value) { audio_level_ = value; }
+
+  const absl::optional<AbsoluteCaptureTime>& absolute_capture_time() const {
+    return absolute_capture_time_;
+  }
+  void set_absolute_capture_time(
+      const absl::optional<AbsoluteCaptureTime>& value) {
+    absolute_capture_time_ = value;
+  }
+
+  int64_t receive_time_ms() const { return receive_time_ms_; }
+  void set_receive_time_ms(int64_t value) { receive_time_ms_ = value; }
+
+ private:
+  // Fields from the RTP header:
+  // https://tools.ietf.org/html/rfc3550#section-5.1
+  uint32_t ssrc_;
+  std::vector<uint32_t> csrcs_;
+  uint32_t rtp_timestamp_;
+
+  // Fields from the Audio Level header extension:
+  // https://tools.ietf.org/html/rfc6464#section-3
+  absl::optional<uint8_t> audio_level_;
+
+  // Fields from the Absolute Capture Time header extension:
+  // http://www.webrtc.org/experiments/rtp-hdrext/abs-capture-time
+  absl::optional<AbsoluteCaptureTime> absolute_capture_time_;
+
+  // Local |webrtc::Clock|-based timestamp of when the packet was received.
+  int64_t receive_time_ms_;
+};
+
+bool operator==(const RtpPacketInfo& lhs, const RtpPacketInfo& rhs);
+
+inline bool operator!=(const RtpPacketInfo& lhs, const RtpPacketInfo& rhs) {
+  return !(lhs == rhs);
+}
+
+}  // namespace webrtc
+
+#endif  // API_RTP_PACKET_INFO_H_
diff --git a/webrtc/api/rtp_packet_infos.h b/webrtc/api/rtp_packet_infos.h
new file mode 100644
index 0000000..d636464
--- /dev/null
+++ b/webrtc/api/rtp_packet_infos.h
@@ -0,0 +1,130 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_RTP_PACKET_INFOS_H_
+#define API_RTP_PACKET_INFOS_H_
+
+#include <cstdint>
+#include <utility>
+#include <vector>
+
+#include "api/ref_counted_base.h"
+#include "api/rtp_packet_info.h"
+#include "api/scoped_refptr.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+// Semi-immutable structure to hold information about packets used to assemble
+// an audio or video frame. Uses internal reference counting to make it very
+// cheap to copy.
+//
+// We should ideally just use |std::vector<RtpPacketInfo>| and have it
+// |std::move()|-ed as the per-packet information is transferred from one object
+// to another. But moving the info, instead of copying it, is not easily done
+// for the current video code.
+class RTC_EXPORT RtpPacketInfos {
+ public:
+  using vector_type = std::vector<RtpPacketInfo>;
+
+  using value_type = vector_type::value_type;
+  using size_type = vector_type::size_type;
+  using difference_type = vector_type::difference_type;
+  using const_reference = vector_type::const_reference;
+  using const_pointer = vector_type::const_pointer;
+  using const_iterator = vector_type::const_iterator;
+  using const_reverse_iterator = vector_type::const_reverse_iterator;
+
+  using reference = const_reference;
+  using pointer = const_pointer;
+  using iterator = const_iterator;
+  using reverse_iterator = const_reverse_iterator;
+
+  RtpPacketInfos() {}
+  explicit RtpPacketInfos(const vector_type& entries)
+      : data_(Data::Create(entries)) {}
+
+  explicit RtpPacketInfos(vector_type&& entries)
+      : data_(Data::Create(std::move(entries))) {}
+
+  RtpPacketInfos(const RtpPacketInfos& other) = default;
+  RtpPacketInfos(RtpPacketInfos&& other) = default;
+  RtpPacketInfos& operator=(const RtpPacketInfos& other) = default;
+  RtpPacketInfos& operator=(RtpPacketInfos&& other) = default;
+
+  const_reference operator[](size_type pos) const { return entries()[pos]; }
+
+  const_reference at(size_type pos) const { return entries().at(pos); }
+  const_reference front() const { return entries().front(); }
+  const_reference back() const { return entries().back(); }
+
+  const_iterator begin() const { return entries().begin(); }
+  const_iterator end() const { return entries().end(); }
+  const_reverse_iterator rbegin() const { return entries().rbegin(); }
+  const_reverse_iterator rend() const { return entries().rend(); }
+
+  const_iterator cbegin() const { return entries().cbegin(); }
+  const_iterator cend() const { return entries().cend(); }
+  const_reverse_iterator crbegin() const { return entries().crbegin(); }
+  const_reverse_iterator crend() const { return entries().crend(); }
+
+  bool empty() const { return entries().empty(); }
+  size_type size() const { return entries().size(); }
+
+ private:
+  class Data : public rtc::RefCountedBase {
+   public:
+    static rtc::scoped_refptr<Data> Create(const vector_type& entries) {
+      // Performance optimization for the empty case.
+      if (entries.empty()) {
+        return nullptr;
+      }
+
+      return new Data(entries);
+    }
+
+    static rtc::scoped_refptr<Data> Create(vector_type&& entries) {
+      // Performance optimization for the empty case.
+      if (entries.empty()) {
+        return nullptr;
+      }
+
+      return new Data(std::move(entries));
+    }
+
+    const vector_type& entries() const { return entries_; }
+
+   private:
+    explicit Data(const vector_type& entries) : entries_(entries) {}
+    explicit Data(vector_type&& entries) : entries_(std::move(entries)) {}
+    ~Data() override {}
+
+    const vector_type entries_;
+  };
+
+  static const vector_type& empty_entries() {
+    static const vector_type& value = *new vector_type();
+    return value;
+  }
+
+  const vector_type& entries() const {
+    if (data_ != nullptr) {
+      return data_->entries();
+    } else {
+      return empty_entries();
+    }
+  }
+
+  rtc::scoped_refptr<Data> data_;
+};
+
+}  // namespace webrtc
+
+#endif  // API_RTP_PACKET_INFOS_H_
diff --git a/webrtc/api/scoped_refptr.h b/webrtc/api/scoped_refptr.h
new file mode 100644
index 0000000..fa4e83d
--- /dev/null
+++ b/webrtc/api/scoped_refptr.h
@@ -0,0 +1,164 @@
+/*
+ *  Copyright 2011 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+// Originally these classes are from Chromium.
+// http://src.chromium.org/viewvc/chrome/trunk/src/base/memory/ref_counted.h?view=markup
+
+//
+// A smart pointer class for reference counted objects.  Use this class instead
+// of calling AddRef and Release manually on a reference counted object to
+// avoid common memory leaks caused by forgetting to Release an object
+// reference.  Sample usage:
+//
+//   class MyFoo : public RefCounted<MyFoo> {
+//    ...
+//   };
+//
+//   void some_function() {
+//     scoped_refptr<MyFoo> foo = new MyFoo();
+//     foo->Method(param);
+//     // |foo| is released when this function returns
+//   }
+//
+//   void some_other_function() {
+//     scoped_refptr<MyFoo> foo = new MyFoo();
+//     ...
+//     foo = nullptr;  // explicitly releases |foo|
+//     ...
+//     if (foo)
+//       foo->Method(param);
+//   }
+//
+// The above examples show how scoped_refptr<T> acts like a pointer to T.
+// Given two scoped_refptr<T> classes, it is also possible to exchange
+// references between the two objects, like so:
+//
+//   {
+//     scoped_refptr<MyFoo> a = new MyFoo();
+//     scoped_refptr<MyFoo> b;
+//
+//     b.swap(a);
+//     // now, |b| references the MyFoo object, and |a| references null.
+//   }
+//
+// To make both |a| and |b| in the above example reference the same MyFoo
+// object, simply use the assignment operator:
+//
+//   {
+//     scoped_refptr<MyFoo> a = new MyFoo();
+//     scoped_refptr<MyFoo> b;
+//
+//     b = a;
+//     // now, |a| and |b| each own a reference to the same MyFoo object.
+//   }
+//
+
+#ifndef API_SCOPED_REFPTR_H_
+#define API_SCOPED_REFPTR_H_
+
+#include <memory>
+#include <utility>
+
+namespace rtc {
+
+template <class T>
+class scoped_refptr {
+ public:
+  typedef T element_type;
+
+  scoped_refptr() : ptr_(nullptr) {}
+
+  scoped_refptr(T* p) : ptr_(p) {  // NOLINT(runtime/explicit)
+    if (ptr_)
+      ptr_->AddRef();
+  }
+
+  scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) {
+    if (ptr_)
+      ptr_->AddRef();
+  }
+
+  template <typename U>
+  scoped_refptr(const scoped_refptr<U>& r) : ptr_(r.get()) {
+    if (ptr_)
+      ptr_->AddRef();
+  }
+
+  // Move constructors.
+  scoped_refptr(scoped_refptr<T>&& r) noexcept : ptr_(r.release()) {}
+
+  template <typename U>
+  scoped_refptr(scoped_refptr<U>&& r) noexcept : ptr_(r.release()) {}
+
+  ~scoped_refptr() {
+    if (ptr_)
+      ptr_->Release();
+  }
+
+  T* get() const { return ptr_; }
+  operator T*() const { return ptr_; }
+  T* operator->() const { return ptr_; }
+
+  // Returns the (possibly null) raw pointer, and makes the scoped_refptr hold a
+  // null pointer, all without touching the reference count of the underlying
+  // pointed-to object. The object is still reference counted, and the caller of
+  // release() is now the proud owner of one reference, so it is responsible for
+  // calling Release() once on the object when no longer using it.
+  T* release() {
+    T* retVal = ptr_;
+    ptr_ = nullptr;
+    return retVal;
+  }
+
+  scoped_refptr<T>& operator=(T* p) {
+    // AddRef first so that self assignment should work
+    if (p)
+      p->AddRef();
+    if (ptr_)
+      ptr_->Release();
+    ptr_ = p;
+    return *this;
+  }
+
+  scoped_refptr<T>& operator=(const scoped_refptr<T>& r) {
+    return *this = r.ptr_;
+  }
+
+  template <typename U>
+  scoped_refptr<T>& operator=(const scoped_refptr<U>& r) {
+    return *this = r.get();
+  }
+
+  scoped_refptr<T>& operator=(scoped_refptr<T>&& r) noexcept {
+    scoped_refptr<T>(std::move(r)).swap(*this);
+    return *this;
+  }
+
+  template <typename U>
+  scoped_refptr<T>& operator=(scoped_refptr<U>&& r) noexcept {
+    scoped_refptr<T>(std::move(r)).swap(*this);
+    return *this;
+  }
+
+  void swap(T** pp) noexcept {
+    T* p = ptr_;
+    ptr_ = *pp;
+    *pp = p;
+  }
+
+  void swap(scoped_refptr<T>& r) noexcept { swap(&r.ptr_); }
+
+ protected:
+  T* ptr_;
+};
+
+}  // namespace rtc
+
+#endif  // API_SCOPED_REFPTR_H_
diff --git a/webrtc/api/task_queue/queued_task.h b/webrtc/api/task_queue/queued_task.h
new file mode 100644
index 0000000..5748628
--- /dev/null
+++ b/webrtc/api/task_queue/queued_task.h
@@ -0,0 +1,32 @@
+/*
+ *  Copyright 2018 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_TASK_QUEUE_QUEUED_TASK_H_
+#define API_TASK_QUEUE_QUEUED_TASK_H_
+
+namespace webrtc {
+
+// Base interface for asynchronously executed tasks.
+// The interface basically consists of a single function, Run(), that executes
+// on the target queue.  For more details see the Run() method and TaskQueue.
+class QueuedTask {
+ public:
+  virtual ~QueuedTask() = default;
+
+  // Main routine that will run when the task is executed on the desired queue.
+  // The task should return |true| to indicate that it should be deleted or
+  // |false| to indicate that the queue should consider ownership of the task
+  // having been transferred.  Returning |false| can be useful if a task has
+  // re-posted itself to a different queue or is otherwise being re-used.
+  virtual bool Run() = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // API_TASK_QUEUE_QUEUED_TASK_H_
diff --git a/webrtc/api/task_queue/task_queue_base.cc b/webrtc/api/task_queue/task_queue_base.cc
new file mode 100644
index 0000000..7d3539a
--- /dev/null
+++ b/webrtc/api/task_queue/task_queue_base.cc
@@ -0,0 +1,79 @@
+/*
+ *  Copyright 2019 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include "api/task_queue/task_queue_base.h"
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "rtc_base/checks.h"
+
+#if defined(ABSL_HAVE_THREAD_LOCAL)
+
+namespace webrtc {
+namespace {
+
+ABSL_CONST_INIT thread_local TaskQueueBase* current = nullptr;
+
+}  // namespace
+
+TaskQueueBase* TaskQueueBase::Current() {
+  return current;
+}
+
+TaskQueueBase::CurrentTaskQueueSetter::CurrentTaskQueueSetter(
+    TaskQueueBase* task_queue)
+    : previous_(current) {
+  current = task_queue;
+}
+
+TaskQueueBase::CurrentTaskQueueSetter::~CurrentTaskQueueSetter() {
+  current = previous_;
+}
+}  // namespace webrtc
+
+#elif defined(WEBRTC_POSIX)
+
+#include <pthread.h>
+
+namespace webrtc {
+namespace {
+
+ABSL_CONST_INIT pthread_key_t g_queue_ptr_tls = 0;
+
+void InitializeTls() {
+  RTC_CHECK(pthread_key_create(&g_queue_ptr_tls, nullptr) == 0);
+}
+
+pthread_key_t GetQueuePtrTls() {
+  static pthread_once_t init_once = PTHREAD_ONCE_INIT;
+  RTC_CHECK(pthread_once(&init_once, &InitializeTls) == 0);
+  return g_queue_ptr_tls;
+}
+
+}  // namespace
+
+TaskQueueBase* TaskQueueBase::Current() {
+  return static_cast<TaskQueueBase*>(pthread_getspecific(GetQueuePtrTls()));
+}
+
+TaskQueueBase::CurrentTaskQueueSetter::CurrentTaskQueueSetter(
+    TaskQueueBase* task_queue)
+    : previous_(TaskQueueBase::Current()) {
+  pthread_setspecific(GetQueuePtrTls(), task_queue);
+}
+
+TaskQueueBase::CurrentTaskQueueSetter::~CurrentTaskQueueSetter() {
+  pthread_setspecific(GetQueuePtrTls(), previous_);
+}
+
+}  // namespace webrtc
+
+#else
+#error Unsupported platform
+#endif
diff --git a/webrtc/api/task_queue/task_queue_base.h b/webrtc/api/task_queue/task_queue_base.h
new file mode 100644
index 0000000..90b1efd
--- /dev/null
+++ b/webrtc/api/task_queue/task_queue_base.h
@@ -0,0 +1,83 @@
+/*
+ *  Copyright 2019 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_TASK_QUEUE_TASK_QUEUE_BASE_H_
+#define API_TASK_QUEUE_TASK_QUEUE_BASE_H_
+
+#include <memory>
+
+#include "api/task_queue/queued_task.h"
+#include "rtc_base/system/rtc_export.h"
+#include "rtc_base/thread_annotations.h"
+
+namespace webrtc {
+
+// Asynchronously executes tasks in a way that guarantees that they're executed
+// in FIFO order and that tasks never overlap. Tasks may always execute on the
+// same worker thread and they may not. To DCHECK that tasks are executing on a
+// known task queue, use IsCurrent().
+class RTC_LOCKABLE RTC_EXPORT TaskQueueBase {
+ public:
+  // Starts destruction of the task queue.
+  // On return ensures no task are running and no new tasks are able to start
+  // on the task queue.
+  // Responsible for deallocation. Deallocation may happen syncrhoniously during
+  // Delete or asynchronously after Delete returns.
+  // Code not running on the TaskQueue should not make any assumption when
+  // TaskQueue is deallocated and thus should not call any methods after Delete.
+  // Code running on the TaskQueue should not call Delete, but can assume
+  // TaskQueue still exists and may call other methods, e.g. PostTask.
+  virtual void Delete() = 0;
+
+  // Schedules a task to execute. Tasks are executed in FIFO order.
+  // If |task->Run()| returns true, task is deleted on the task queue
+  // before next QueuedTask starts executing.
+  // When a TaskQueue is deleted, pending tasks will not be executed but they
+  // will be deleted. The deletion of tasks may happen synchronously on the
+  // TaskQueue or it may happen asynchronously after TaskQueue is deleted.
+  // This may vary from one implementation to the next so assumptions about
+  // lifetimes of pending tasks should not be made.
+  virtual void PostTask(std::unique_ptr<QueuedTask> task) = 0;
+
+  // Schedules a task to execute a specified number of milliseconds from when
+  // the call is made. The precision should be considered as "best effort"
+  // and in some cases, such as on Windows when all high precision timers have
+  // been used up, can be off by as much as 15 millseconds.
+  virtual void PostDelayedTask(std::unique_ptr<QueuedTask> task,
+                               uint32_t milliseconds) = 0;
+
+  // Returns the task queue that is running the current thread.
+  // Returns nullptr if this thread is not associated with any task queue.
+  static TaskQueueBase* Current();
+  bool IsCurrent() const { return Current() == this; }
+
+ protected:
+  class CurrentTaskQueueSetter {
+   public:
+    explicit CurrentTaskQueueSetter(TaskQueueBase* task_queue);
+    CurrentTaskQueueSetter(const CurrentTaskQueueSetter&) = delete;
+    CurrentTaskQueueSetter& operator=(const CurrentTaskQueueSetter&) = delete;
+    ~CurrentTaskQueueSetter();
+
+   private:
+    TaskQueueBase* const previous_;
+  };
+
+  // Users of the TaskQueue should call Delete instead of directly deleting
+  // this object.
+  virtual ~TaskQueueBase() = default;
+};
+
+struct TaskQueueDeleter {
+  void operator()(TaskQueueBase* task_queue) const { task_queue->Delete(); }
+};
+
+}  // namespace webrtc
+
+#endif  // API_TASK_QUEUE_TASK_QUEUE_BASE_H_
diff --git a/webrtc/api/units/data_rate.cc b/webrtc/api/units/data_rate.cc
new file mode 100644
index 0000000..f9586c5
--- /dev/null
+++ b/webrtc/api/units/data_rate.cc
@@ -0,0 +1,34 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/units/data_rate.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+
+std::string ToString(DataRate value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf bps";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf bps";
+  } else {
+    if (value.bps() == 0 || value.bps() % 1000 != 0) {
+      sb << value.bps() << " bps";
+    } else {
+      sb << value.kbps() << " kbps";
+    }
+  }
+  return sb.str();
+}
+}  // namespace webrtc
diff --git a/webrtc/api/units/data_rate.h b/webrtc/api/units/data_rate.h
new file mode 100644
index 0000000..5c8a61f
--- /dev/null
+++ b/webrtc/api/units/data_rate.h
@@ -0,0 +1,155 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_UNITS_DATA_RATE_H_
+#define API_UNITS_DATA_RATE_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <limits>
+#include <string>
+#include <type_traits>
+
+#include "api/units/data_size.h"
+#include "api/units/frequency.h"
+#include "api/units/time_delta.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+// DataRate is a class that represents a given data rate. This can be used to
+// represent bandwidth, encoding bitrate, etc. The internal storage is bits per
+// second (bps).
+class DataRate final : public rtc_units_impl::RelativeUnit<DataRate> {
+ public:
+  template <typename T>
+  static constexpr DataRate BitsPerSec(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+  template <typename T>
+  static constexpr DataRate BytesPerSec(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(8, value);
+  }
+  template <typename T>
+  static constexpr DataRate KilobitsPerSec(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1000, value);
+  }
+  static constexpr DataRate Infinity() { return PlusInfinity(); }
+
+  DataRate() = delete;
+
+  template <typename T = int64_t>
+  constexpr T bps() const {
+    return ToValue<T>();
+  }
+  template <typename T = int64_t>
+  constexpr T bytes_per_sec() const {
+    return ToFraction<8, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T kbps() const {
+    return ToFraction<1000, T>();
+  }
+  constexpr int64_t bps_or(int64_t fallback_value) const {
+    return ToValueOr(fallback_value);
+  }
+  constexpr int64_t kbps_or(int64_t fallback_value) const {
+    return ToFractionOr<1000>(fallback_value);
+  }
+
+ private:
+  // Bits per second used internally to simplify debugging by making the value
+  // more recognizable.
+  friend class rtc_units_impl::UnitBase<DataRate>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = true;
+};
+
+namespace data_rate_impl {
+inline constexpr int64_t Microbits(const DataSize& size) {
+  constexpr int64_t kMaxBeforeConversion =
+      std::numeric_limits<int64_t>::max() / 8000000;
+  RTC_DCHECK_LE(size.bytes(), kMaxBeforeConversion)
+      << "size is too large to be expressed in microbits";
+  return size.bytes() * 8000000;
+}
+
+inline constexpr int64_t MillibytePerSec(const DataRate& size) {
+  constexpr int64_t kMaxBeforeConversion =
+      std::numeric_limits<int64_t>::max() / (1000 / 8);
+  RTC_DCHECK_LE(size.bps(), kMaxBeforeConversion)
+      << "rate is too large to be expressed in microbytes per second";
+  return size.bps() * (1000 / 8);
+}
+}  // namespace data_rate_impl
+
+inline constexpr DataRate operator/(const DataSize size,
+                                    const TimeDelta duration) {
+  return DataRate::BitsPerSec(data_rate_impl::Microbits(size) / duration.us());
+}
+inline constexpr TimeDelta operator/(const DataSize size, const DataRate rate) {
+  return TimeDelta::Micros(data_rate_impl::Microbits(size) / rate.bps());
+}
+inline constexpr DataSize operator*(const DataRate rate,
+                                    const TimeDelta duration) {
+  int64_t microbits = rate.bps() * duration.us();
+  return DataSize::Bytes((microbits + 4000000) / 8000000);
+}
+inline constexpr DataSize operator*(const TimeDelta duration,
+                                    const DataRate rate) {
+  return rate * duration;
+}
+
+inline constexpr DataSize operator/(const DataRate rate,
+                                    const Frequency frequency) {
+  int64_t millihertz = frequency.millihertz<int64_t>();
+  // Note that the value is truncated here reather than rounded, potentially
+  // introducing an error of .5 bytes if rounding were expected.
+  return DataSize::Bytes(data_rate_impl::MillibytePerSec(rate) / millihertz);
+}
+inline constexpr Frequency operator/(const DataRate rate, const DataSize size) {
+  return Frequency::MilliHertz(data_rate_impl::MillibytePerSec(rate) /
+                               size.bytes());
+}
+inline constexpr DataRate operator*(const DataSize size,
+                                    const Frequency frequency) {
+  RTC_DCHECK(frequency.IsZero() ||
+             size.bytes() <= std::numeric_limits<int64_t>::max() / 8 /
+                                 frequency.millihertz<int64_t>());
+  int64_t millibits_per_second =
+      size.bytes() * 8 * frequency.millihertz<int64_t>();
+  return DataRate::BitsPerSec((millibits_per_second + 500) / 1000);
+}
+inline constexpr DataRate operator*(const Frequency frequency,
+                                    const DataSize size) {
+  return size * frequency;
+}
+
+std::string ToString(DataRate value);
+inline std::string ToLogString(DataRate value) {
+  return ToString(value);
+}
+
+#ifdef UNIT_TEST
+inline std::ostream& operator<<(  // no-presubmit-check TODO(webrtc:8982)
+    std::ostream& stream,         // no-presubmit-check TODO(webrtc:8982)
+    DataRate value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_DATA_RATE_H_
diff --git a/webrtc/api/units/data_size.cc b/webrtc/api/units/data_size.cc
new file mode 100644
index 0000000..45487df
--- /dev/null
+++ b/webrtc/api/units/data_size.cc
@@ -0,0 +1,30 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/units/data_size.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+
+std::string ToString(DataSize value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf bytes";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf bytes";
+  } else {
+    sb << value.bytes() << " bytes";
+  }
+  return sb.str();
+}
+}  // namespace webrtc
diff --git a/webrtc/api/units/data_size.h b/webrtc/api/units/data_size.h
new file mode 100644
index 0000000..27a2a4e
--- /dev/null
+++ b/webrtc/api/units/data_size.h
@@ -0,0 +1,66 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_UNITS_DATA_SIZE_H_
+#define API_UNITS_DATA_SIZE_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <string>
+#include <type_traits>
+
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+// DataSize is a class represeting a count of bytes.
+class DataSize final : public rtc_units_impl::RelativeUnit<DataSize> {
+ public:
+  template <typename T>
+  static constexpr DataSize Bytes(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+  static constexpr DataSize Infinity() { return PlusInfinity(); }
+
+  DataSize() = delete;
+
+  template <typename T = int64_t>
+  constexpr T bytes() const {
+    return ToValue<T>();
+  }
+
+  constexpr int64_t bytes_or(int64_t fallback_value) const {
+    return ToValueOr(fallback_value);
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<DataSize>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = true;
+};
+
+std::string ToString(DataSize value);
+inline std::string ToLogString(DataSize value) {
+  return ToString(value);
+}
+
+#ifdef UNIT_TEST
+inline std::ostream& operator<<(  // no-presubmit-check TODO(webrtc:8982)
+    std::ostream& stream,         // no-presubmit-check TODO(webrtc:8982)
+    DataSize value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_DATA_SIZE_H_
diff --git a/webrtc/api/units/frequency.cc b/webrtc/api/units/frequency.cc
new file mode 100644
index 0000000..2d938a2
--- /dev/null
+++ b/webrtc/api/units/frequency.cc
@@ -0,0 +1,29 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include "api/units/frequency.h"
+
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+std::string ToString(Frequency value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf Hz";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf Hz";
+  } else if (value.millihertz<int64_t>() % 1000 != 0) {
+    sb.AppendFormat("%.3f Hz", value.hertz<double>());
+  } else {
+    sb << value.hertz<int64_t>() << " Hz";
+  }
+  return sb.str();
+}
+}  // namespace webrtc
diff --git a/webrtc/api/units/frequency.h b/webrtc/api/units/frequency.h
new file mode 100644
index 0000000..88912c6
--- /dev/null
+++ b/webrtc/api/units/frequency.h
@@ -0,0 +1,101 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_UNITS_FREQUENCY_H_
+#define API_UNITS_FREQUENCY_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <cstdlib>
+#include <limits>
+#include <string>
+#include <type_traits>
+
+#include "api/units/time_delta.h"
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+
+class Frequency final : public rtc_units_impl::RelativeUnit<Frequency> {
+ public:
+  template <typename T>
+  static constexpr Frequency MilliHertz(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+  template <typename T>
+  static constexpr Frequency Hertz(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000, value);
+  }
+  template <typename T>
+  static constexpr Frequency KiloHertz(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000'000, value);
+  }
+
+  Frequency() = delete;
+
+  template <typename T = int64_t>
+  constexpr T hertz() const {
+    return ToFraction<1000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T millihertz() const {
+    return ToValue<T>();
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<Frequency>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = true;
+};
+
+inline constexpr Frequency operator/(int64_t nominator,
+                                     const TimeDelta& interval) {
+  constexpr int64_t kKiloPerMicro = 1000 * 1000000;
+  RTC_DCHECK_LE(nominator, std::numeric_limits<int64_t>::max() / kKiloPerMicro);
+  RTC_CHECK(interval.IsFinite());
+  RTC_CHECK(!interval.IsZero());
+  return Frequency::MilliHertz(nominator * kKiloPerMicro / interval.us());
+}
+
+inline constexpr TimeDelta operator/(int64_t nominator,
+                                     const Frequency& frequency) {
+  constexpr int64_t kMegaPerMilli = 1000000 * 1000;
+  RTC_DCHECK_LE(nominator, std::numeric_limits<int64_t>::max() / kMegaPerMilli);
+  RTC_CHECK(frequency.IsFinite());
+  RTC_CHECK(!frequency.IsZero());
+  return TimeDelta::Micros(nominator * kMegaPerMilli / frequency.millihertz());
+}
+
+inline constexpr double operator*(Frequency frequency, TimeDelta time_delta) {
+  return frequency.hertz<double>() * time_delta.seconds<double>();
+}
+inline constexpr double operator*(TimeDelta time_delta, Frequency frequency) {
+  return frequency * time_delta;
+}
+
+std::string ToString(Frequency value);
+inline std::string ToLogString(Frequency value) {
+  return ToString(value);
+}
+
+#ifdef UNIT_TEST
+inline std::ostream& operator<<(  // no-presubmit-check TODO(webrtc:8982)
+    std::ostream& stream,         // no-presubmit-check TODO(webrtc:8982)
+    Frequency value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+#endif  // API_UNITS_FREQUENCY_H_
diff --git a/webrtc/api/units/time_delta.cc b/webrtc/api/units/time_delta.cc
new file mode 100644
index 0000000..31bf3e0
--- /dev/null
+++ b/webrtc/api/units/time_delta.cc
@@ -0,0 +1,36 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/units/time_delta.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+
+std::string ToString(TimeDelta value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf ms";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf ms";
+  } else {
+    if (value.us() == 0 || (value.us() % 1000) != 0)
+      sb << value.us() << " us";
+    else if (value.ms() % 1000 != 0)
+      sb << value.ms() << " ms";
+    else
+      sb << value.seconds() << " s";
+  }
+  return sb.str();
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/units/time_delta.h b/webrtc/api/units/time_delta.h
new file mode 100644
index 0000000..173affc
--- /dev/null
+++ b/webrtc/api/units/time_delta.h
@@ -0,0 +1,105 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_UNITS_TIME_DELTA_H_
+#define API_UNITS_TIME_DELTA_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <cstdlib>
+#include <string>
+#include <type_traits>
+
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+
+// TimeDelta represents the difference between two timestamps. Commonly this can
+// be a duration. However since two Timestamps are not guaranteed to have the
+// same epoch (they might come from different computers, making exact
+// synchronisation infeasible), the duration covered by a TimeDelta can be
+// undefined. To simplify usage, it can be constructed and converted to
+// different units, specifically seconds (s), milliseconds (ms) and
+// microseconds (us).
+class TimeDelta final : public rtc_units_impl::RelativeUnit<TimeDelta> {
+ public:
+  template <typename T>
+  static constexpr TimeDelta Seconds(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000'000, value);
+  }
+  template <typename T>
+  static constexpr TimeDelta Millis(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000, value);
+  }
+  template <typename T>
+  static constexpr TimeDelta Micros(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+
+  TimeDelta() = delete;
+
+  template <typename T = int64_t>
+  constexpr T seconds() const {
+    return ToFraction<1000000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T ms() const {
+    return ToFraction<1000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T us() const {
+    return ToValue<T>();
+  }
+  template <typename T = int64_t>
+  constexpr T ns() const {
+    return ToMultiple<1000, T>();
+  }
+
+  constexpr int64_t seconds_or(int64_t fallback_value) const {
+    return ToFractionOr<1000000>(fallback_value);
+  }
+  constexpr int64_t ms_or(int64_t fallback_value) const {
+    return ToFractionOr<1000>(fallback_value);
+  }
+  constexpr int64_t us_or(int64_t fallback_value) const {
+    return ToValueOr(fallback_value);
+  }
+
+  constexpr TimeDelta Abs() const {
+    return us() < 0 ? TimeDelta::Micros(-us()) : *this;
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<TimeDelta>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = false;
+};
+
+std::string ToString(TimeDelta value);
+inline std::string ToLogString(TimeDelta value) {
+  return ToString(value);
+}
+
+#ifdef UNIT_TEST
+inline std::ostream& operator<<(  // no-presubmit-check TODO(webrtc:8982)
+    std::ostream& stream,         // no-presubmit-check TODO(webrtc:8982)
+    TimeDelta value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_TIME_DELTA_H_
diff --git a/webrtc/api/units/timestamp.cc b/webrtc/api/units/timestamp.cc
new file mode 100644
index 0000000..fc4f419
--- /dev/null
+++ b/webrtc/api/units/timestamp.cc
@@ -0,0 +1,34 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/units/timestamp.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+std::string ToString(Timestamp value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf ms";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf ms";
+  } else {
+    if (value.us() == 0 || (value.us() % 1000) != 0)
+      sb << value.us() << " us";
+    else if (value.ms() % 1000 != 0)
+      sb << value.ms() << " ms";
+    else
+      sb << value.seconds() << " s";
+  }
+  return sb.str();
+}
+}  // namespace webrtc
diff --git a/webrtc/api/units/timestamp.h b/webrtc/api/units/timestamp.h
new file mode 100644
index 0000000..f83477e
--- /dev/null
+++ b/webrtc/api/units/timestamp.h
@@ -0,0 +1,138 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_UNITS_TIMESTAMP_H_
+#define API_UNITS_TIMESTAMP_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <string>
+#include <type_traits>
+
+#include "api/units/time_delta.h"
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+// Timestamp represents the time that has passed since some unspecified epoch.
+// The epoch is assumed to be before any represented timestamps, this means that
+// negative values are not valid. The most notable feature is that the
+// difference of two Timestamps results in a TimeDelta.
+class Timestamp final : public rtc_units_impl::UnitBase<Timestamp> {
+ public:
+  template <typename T>
+  static constexpr Timestamp Seconds(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000'000, value);
+  }
+  template <typename T>
+  static constexpr Timestamp Millis(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000, value);
+  }
+  template <typename T>
+  static constexpr Timestamp Micros(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+
+  Timestamp() = delete;
+
+  template <typename T = int64_t>
+  constexpr T seconds() const {
+    return ToFraction<1000000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T ms() const {
+    return ToFraction<1000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T us() const {
+    return ToValue<T>();
+  }
+
+  constexpr int64_t seconds_or(int64_t fallback_value) const {
+    return ToFractionOr<1000000>(fallback_value);
+  }
+  constexpr int64_t ms_or(int64_t fallback_value) const {
+    return ToFractionOr<1000>(fallback_value);
+  }
+  constexpr int64_t us_or(int64_t fallback_value) const {
+    return ToValueOr(fallback_value);
+  }
+
+  constexpr Timestamp operator+(const TimeDelta delta) const {
+    if (IsPlusInfinity() || delta.IsPlusInfinity()) {
+      RTC_DCHECK(!IsMinusInfinity());
+      RTC_DCHECK(!delta.IsMinusInfinity());
+      return PlusInfinity();
+    } else if (IsMinusInfinity() || delta.IsMinusInfinity()) {
+      RTC_DCHECK(!IsPlusInfinity());
+      RTC_DCHECK(!delta.IsPlusInfinity());
+      return MinusInfinity();
+    }
+    return Timestamp::Micros(us() + delta.us());
+  }
+  constexpr Timestamp operator-(const TimeDelta delta) const {
+    if (IsPlusInfinity() || delta.IsMinusInfinity()) {
+      RTC_DCHECK(!IsMinusInfinity());
+      RTC_DCHECK(!delta.IsPlusInfinity());
+      return PlusInfinity();
+    } else if (IsMinusInfinity() || delta.IsPlusInfinity()) {
+      RTC_DCHECK(!IsPlusInfinity());
+      RTC_DCHECK(!delta.IsMinusInfinity());
+      return MinusInfinity();
+    }
+    return Timestamp::Micros(us() - delta.us());
+  }
+  constexpr TimeDelta operator-(const Timestamp other) const {
+    if (IsPlusInfinity() || other.IsMinusInfinity()) {
+      RTC_DCHECK(!IsMinusInfinity());
+      RTC_DCHECK(!other.IsPlusInfinity());
+      return TimeDelta::PlusInfinity();
+    } else if (IsMinusInfinity() || other.IsPlusInfinity()) {
+      RTC_DCHECK(!IsPlusInfinity());
+      RTC_DCHECK(!other.IsMinusInfinity());
+      return TimeDelta::MinusInfinity();
+    }
+    return TimeDelta::Micros(us() - other.us());
+  }
+  constexpr Timestamp& operator-=(const TimeDelta delta) {
+    *this = *this - delta;
+    return *this;
+  }
+  constexpr Timestamp& operator+=(const TimeDelta delta) {
+    *this = *this + delta;
+    return *this;
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<Timestamp>;
+  using UnitBase::UnitBase;
+  static constexpr bool one_sided = true;
+};
+
+std::string ToString(Timestamp value);
+inline std::string ToLogString(Timestamp value) {
+  return ToString(value);
+}
+
+#ifdef UNIT_TEST
+inline std::ostream& operator<<(  // no-presubmit-check TODO(webrtc:8982)
+    std::ostream& stream,         // no-presubmit-check TODO(webrtc:8982)
+    Timestamp value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_TIMESTAMP_H_
diff --git a/webrtc/api/video/color_space.cc b/webrtc/api/video/color_space.cc
new file mode 100644
index 0000000..710bb43
--- /dev/null
+++ b/webrtc/api/video/color_space.cc
@@ -0,0 +1,187 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/video/color_space.h"
+
+namespace webrtc {
+namespace {
+// Try to convert |enum_value| into the enum class T. |enum_bitmask| is created
+// by the funciton below. Returns true if conversion was successful, false
+// otherwise.
+template <typename T>
+bool SetFromUint8(uint8_t enum_value, uint64_t enum_bitmask, T* out) {
+  if ((enum_value < 64) && ((enum_bitmask >> enum_value) & 1)) {
+    *out = static_cast<T>(enum_value);
+    return true;
+  }
+  return false;
+}
+
+// This function serves as an assert for the constexpr function below. It's on
+// purpose not declared as constexpr so that it causes a build problem if enum
+// values of 64 or above are used. The bitmask and the code generating it would
+// have to be extended if the standard is updated to include enum values >= 64.
+int EnumMustBeLessThan64() {
+  return -1;
+}
+
+template <typename T, size_t N>
+constexpr int MakeMask(const int index, const int length, T (&values)[N]) {
+  return length > 1
+             ? (MakeMask(index, 1, values) +
+                MakeMask(index + 1, length - 1, values))
+             : (static_cast<uint8_t>(values[index]) < 64
+                    ? (uint64_t{1} << static_cast<uint8_t>(values[index]))
+                    : EnumMustBeLessThan64());
+}
+
+// Create a bitmask where each bit corresponds to one potential enum value.
+// |values| should be an array listing all possible enum values. The bit is set
+// to one if the corresponding enum exists. Only works for enums with values
+// less than 64.
+template <typename T, size_t N>
+constexpr uint64_t CreateEnumBitmask(T (&values)[N]) {
+  return MakeMask(0, N, values);
+}
+
+bool SetChromaSitingFromUint8(uint8_t enum_value,
+                              ColorSpace::ChromaSiting* chroma_siting) {
+  constexpr ColorSpace::ChromaSiting kChromaSitings[] = {
+      ColorSpace::ChromaSiting::kUnspecified,
+      ColorSpace::ChromaSiting::kCollocated, ColorSpace::ChromaSiting::kHalf};
+  constexpr uint64_t enum_bitmask = CreateEnumBitmask(kChromaSitings);
+
+  return SetFromUint8(enum_value, enum_bitmask, chroma_siting);
+}
+
+}  // namespace
+
+ColorSpace::ColorSpace() = default;
+ColorSpace::ColorSpace(const ColorSpace& other) = default;
+ColorSpace::ColorSpace(ColorSpace&& other) = default;
+ColorSpace& ColorSpace::operator=(const ColorSpace& other) = default;
+
+ColorSpace::ColorSpace(PrimaryID primaries,
+                       TransferID transfer,
+                       MatrixID matrix,
+                       RangeID range)
+    : ColorSpace(primaries,
+                 transfer,
+                 matrix,
+                 range,
+                 ChromaSiting::kUnspecified,
+                 ChromaSiting::kUnspecified,
+                 nullptr) {}
+
+ColorSpace::ColorSpace(PrimaryID primaries,
+                       TransferID transfer,
+                       MatrixID matrix,
+                       RangeID range,
+                       ChromaSiting chroma_siting_horz,
+                       ChromaSiting chroma_siting_vert,
+                       const HdrMetadata* hdr_metadata)
+    : primaries_(primaries),
+      transfer_(transfer),
+      matrix_(matrix),
+      range_(range),
+      chroma_siting_horizontal_(chroma_siting_horz),
+      chroma_siting_vertical_(chroma_siting_vert),
+      hdr_metadata_(hdr_metadata ? absl::make_optional(*hdr_metadata)
+                                 : absl::nullopt) {}
+
+ColorSpace::PrimaryID ColorSpace::primaries() const {
+  return primaries_;
+}
+
+ColorSpace::TransferID ColorSpace::transfer() const {
+  return transfer_;
+}
+
+ColorSpace::MatrixID ColorSpace::matrix() const {
+  return matrix_;
+}
+
+ColorSpace::RangeID ColorSpace::range() const {
+  return range_;
+}
+
+ColorSpace::ChromaSiting ColorSpace::chroma_siting_horizontal() const {
+  return chroma_siting_horizontal_;
+}
+
+ColorSpace::ChromaSiting ColorSpace::chroma_siting_vertical() const {
+  return chroma_siting_vertical_;
+}
+
+const HdrMetadata* ColorSpace::hdr_metadata() const {
+  return hdr_metadata_ ? &*hdr_metadata_ : nullptr;
+}
+
+bool ColorSpace::set_primaries_from_uint8(uint8_t enum_value) {
+  constexpr PrimaryID kPrimaryIds[] = {
+      PrimaryID::kBT709,      PrimaryID::kUnspecified, PrimaryID::kBT470M,
+      PrimaryID::kBT470BG,    PrimaryID::kSMPTE170M,   PrimaryID::kSMPTE240M,
+      PrimaryID::kFILM,       PrimaryID::kBT2020,      PrimaryID::kSMPTEST428,
+      PrimaryID::kSMPTEST431, PrimaryID::kSMPTEST432,  PrimaryID::kJEDECP22};
+  constexpr uint64_t enum_bitmask = CreateEnumBitmask(kPrimaryIds);
+
+  return SetFromUint8(enum_value, enum_bitmask, &primaries_);
+}
+
+bool ColorSpace::set_transfer_from_uint8(uint8_t enum_value) {
+  constexpr TransferID kTransferIds[] = {
+      TransferID::kBT709,       TransferID::kUnspecified,
+      TransferID::kGAMMA22,     TransferID::kGAMMA28,
+      TransferID::kSMPTE170M,   TransferID::kSMPTE240M,
+      TransferID::kLINEAR,      TransferID::kLOG,
+      TransferID::kLOG_SQRT,    TransferID::kIEC61966_2_4,
+      TransferID::kBT1361_ECG,  TransferID::kIEC61966_2_1,
+      TransferID::kBT2020_10,   TransferID::kBT2020_12,
+      TransferID::kSMPTEST2084, TransferID::kSMPTEST428,
+      TransferID::kARIB_STD_B67};
+  constexpr uint64_t enum_bitmask = CreateEnumBitmask(kTransferIds);
+
+  return SetFromUint8(enum_value, enum_bitmask, &transfer_);
+}
+
+bool ColorSpace::set_matrix_from_uint8(uint8_t enum_value) {
+  constexpr MatrixID kMatrixIds[] = {
+      MatrixID::kRGB,       MatrixID::kBT709,       MatrixID::kUnspecified,
+      MatrixID::kFCC,       MatrixID::kBT470BG,     MatrixID::kSMPTE170M,
+      MatrixID::kSMPTE240M, MatrixID::kYCOCG,       MatrixID::kBT2020_NCL,
+      MatrixID::kBT2020_CL, MatrixID::kSMPTE2085,   MatrixID::kCDNCLS,
+      MatrixID::kCDCLS,     MatrixID::kBT2100_ICTCP};
+  constexpr uint64_t enum_bitmask = CreateEnumBitmask(kMatrixIds);
+
+  return SetFromUint8(enum_value, enum_bitmask, &matrix_);
+}
+
+bool ColorSpace::set_range_from_uint8(uint8_t enum_value) {
+  constexpr RangeID kRangeIds[] = {RangeID::kInvalid, RangeID::kLimited,
+                                   RangeID::kFull, RangeID::kDerived};
+  constexpr uint64_t enum_bitmask = CreateEnumBitmask(kRangeIds);
+
+  return SetFromUint8(enum_value, enum_bitmask, &range_);
+}
+
+bool ColorSpace::set_chroma_siting_horizontal_from_uint8(uint8_t enum_value) {
+  return SetChromaSitingFromUint8(enum_value, &chroma_siting_horizontal_);
+}
+
+bool ColorSpace::set_chroma_siting_vertical_from_uint8(uint8_t enum_value) {
+  return SetChromaSitingFromUint8(enum_value, &chroma_siting_vertical_);
+}
+
+void ColorSpace::set_hdr_metadata(const HdrMetadata* hdr_metadata) {
+  hdr_metadata_ =
+      hdr_metadata ? absl::make_optional(*hdr_metadata) : absl::nullopt;
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/video/color_space.h b/webrtc/api/video/color_space.h
new file mode 100644
index 0000000..a7ad86b
--- /dev/null
+++ b/webrtc/api/video/color_space.h
@@ -0,0 +1,178 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_VIDEO_COLOR_SPACE_H_
+#define API_VIDEO_COLOR_SPACE_H_
+
+#include <stdint.h>
+
+#include "absl/types/optional.h"
+#include "api/video/hdr_metadata.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+// This class represents color information as specified in T-REC H.273,
+// available from https://www.itu.int/rec/T-REC-H.273.
+//
+// WebRTC's supported codecs:
+// - VP9 supports color profiles, see VP9 Bitstream & Decoding Process
+// Specification Version 0.6 Section 7.2.2 "Color config semantics" available
+// from https://www.webmproject.org.
+// - VP8 only supports BT.601, see
+// https://tools.ietf.org/html/rfc6386#section-9.2
+// - H264 uses the exact same representation as T-REC H.273. See T-REC-H.264
+// E.2.1, "VUI parameters semantics", available from
+// https://www.itu.int/rec/T-REC-H.264.
+
+class RTC_EXPORT ColorSpace {
+ public:
+  enum class PrimaryID : uint8_t {
+    // The indices are equal to the values specified in T-REC H.273 Table 2.
+    kBT709 = 1,
+    kUnspecified = 2,
+    kBT470M = 4,
+    kBT470BG = 5,
+    kSMPTE170M = 6,  // Identical to BT601
+    kSMPTE240M = 7,
+    kFILM = 8,
+    kBT2020 = 9,
+    kSMPTEST428 = 10,
+    kSMPTEST431 = 11,
+    kSMPTEST432 = 12,
+    kJEDECP22 = 22,  // Identical to EBU3213-E
+    // When adding/removing entries here, please make sure to do the
+    // corresponding change to kPrimaryIds.
+  };
+
+  enum class TransferID : uint8_t {
+    // The indices are equal to the values specified in T-REC H.273 Table 3.
+    kBT709 = 1,
+    kUnspecified = 2,
+    kGAMMA22 = 4,
+    kGAMMA28 = 5,
+    kSMPTE170M = 6,
+    kSMPTE240M = 7,
+    kLINEAR = 8,
+    kLOG = 9,
+    kLOG_SQRT = 10,
+    kIEC61966_2_4 = 11,
+    kBT1361_ECG = 12,
+    kIEC61966_2_1 = 13,
+    kBT2020_10 = 14,
+    kBT2020_12 = 15,
+    kSMPTEST2084 = 16,
+    kSMPTEST428 = 17,
+    kARIB_STD_B67 = 18,
+    // When adding/removing entries here, please make sure to do the
+    // corresponding change to kTransferIds.
+  };
+
+  enum class MatrixID : uint8_t {
+    // The indices are equal to the values specified in T-REC H.273 Table 4.
+    kRGB = 0,
+    kBT709 = 1,
+    kUnspecified = 2,
+    kFCC = 4,
+    kBT470BG = 5,
+    kSMPTE170M = 6,
+    kSMPTE240M = 7,
+    kYCOCG = 8,
+    kBT2020_NCL = 9,
+    kBT2020_CL = 10,
+    kSMPTE2085 = 11,
+    kCDNCLS = 12,
+    kCDCLS = 13,
+    kBT2100_ICTCP = 14,
+    // When adding/removing entries here, please make sure to do the
+    // corresponding change to kMatrixIds.
+  };
+
+  enum class RangeID {
+    // The indices are equal to the values specified at
+    // https://www.webmproject.org/docs/container/#colour for the element Range.
+    kInvalid = 0,
+    // Limited Rec. 709 color range with RGB values ranging from 16 to 235.
+    kLimited = 1,
+    // Full RGB color range with RGB valees from 0 to 255.
+    kFull = 2,
+    // Range is defined by MatrixCoefficients/TransferCharacteristics.
+    kDerived = 3,
+    // When adding/removing entries here, please make sure to do the
+    // corresponding change to kRangeIds.
+  };
+
+  enum class ChromaSiting {
+    // Chroma siting specifies how chroma is subsampled relative to the luma
+    // samples in a YUV video frame.
+    // The indices are equal to the values specified at
+    // https://www.webmproject.org/docs/container/#colour for the element
+    // ChromaSitingVert and ChromaSitingHorz.
+    kUnspecified = 0,
+    kCollocated = 1,
+    kHalf = 2,
+    // When adding/removing entries here, please make sure to do the
+    // corresponding change to kChromaSitings.
+  };
+
+  ColorSpace();
+  ColorSpace(const ColorSpace& other);
+  ColorSpace(ColorSpace&& other);
+  ColorSpace& operator=(const ColorSpace& other);
+  ColorSpace(PrimaryID primaries,
+             TransferID transfer,
+             MatrixID matrix,
+             RangeID range);
+  ColorSpace(PrimaryID primaries,
+             TransferID transfer,
+             MatrixID matrix,
+             RangeID range,
+             ChromaSiting chroma_siting_horizontal,
+             ChromaSiting chroma_siting_vertical,
+             const HdrMetadata* hdr_metadata);
+  friend bool operator==(const ColorSpace& lhs, const ColorSpace& rhs) {
+    return lhs.primaries_ == rhs.primaries_ && lhs.transfer_ == rhs.transfer_ &&
+           lhs.matrix_ == rhs.matrix_ && lhs.range_ == rhs.range_ &&
+           lhs.chroma_siting_horizontal_ == rhs.chroma_siting_horizontal_ &&
+           lhs.chroma_siting_vertical_ == rhs.chroma_siting_vertical_ &&
+           lhs.hdr_metadata_ == rhs.hdr_metadata_;
+  }
+  friend bool operator!=(const ColorSpace& lhs, const ColorSpace& rhs) {
+    return !(lhs == rhs);
+  }
+
+  PrimaryID primaries() const;
+  TransferID transfer() const;
+  MatrixID matrix() const;
+  RangeID range() const;
+  ChromaSiting chroma_siting_horizontal() const;
+  ChromaSiting chroma_siting_vertical() const;
+  const HdrMetadata* hdr_metadata() const;
+
+  bool set_primaries_from_uint8(uint8_t enum_value);
+  bool set_transfer_from_uint8(uint8_t enum_value);
+  bool set_matrix_from_uint8(uint8_t enum_value);
+  bool set_range_from_uint8(uint8_t enum_value);
+  bool set_chroma_siting_horizontal_from_uint8(uint8_t enum_value);
+  bool set_chroma_siting_vertical_from_uint8(uint8_t enum_value);
+  void set_hdr_metadata(const HdrMetadata* hdr_metadata);
+
+ private:
+  PrimaryID primaries_ = PrimaryID::kUnspecified;
+  TransferID transfer_ = TransferID::kUnspecified;
+  MatrixID matrix_ = MatrixID::kUnspecified;
+  RangeID range_ = RangeID::kInvalid;
+  ChromaSiting chroma_siting_horizontal_ = ChromaSiting::kUnspecified;
+  ChromaSiting chroma_siting_vertical_ = ChromaSiting::kUnspecified;
+  absl::optional<HdrMetadata> hdr_metadata_;
+};
+
+}  // namespace webrtc
+#endif  // API_VIDEO_COLOR_SPACE_H_
diff --git a/webrtc/api/video/hdr_metadata.cc b/webrtc/api/video/hdr_metadata.cc
new file mode 100644
index 0000000..e2a669c
--- /dev/null
+++ b/webrtc/api/video/hdr_metadata.cc
@@ -0,0 +1,21 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/video/hdr_metadata.h"
+
+namespace webrtc {
+
+HdrMasteringMetadata::Chromaticity::Chromaticity() = default;
+
+HdrMasteringMetadata::HdrMasteringMetadata() = default;
+
+HdrMetadata::HdrMetadata() = default;
+
+}  // namespace webrtc
diff --git a/webrtc/api/video/hdr_metadata.h b/webrtc/api/video/hdr_metadata.h
new file mode 100644
index 0000000..e9001a2
--- /dev/null
+++ b/webrtc/api/video/hdr_metadata.h
@@ -0,0 +1,105 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_VIDEO_HDR_METADATA_H_
+#define API_VIDEO_HDR_METADATA_H_
+
+namespace webrtc {
+
+// SMPTE ST 2086 mastering metadata,
+// see https://ieeexplore.ieee.org/document/8353899.
+struct HdrMasteringMetadata {
+  struct Chromaticity {
+    Chromaticity();
+
+    bool operator==(const Chromaticity& rhs) const {
+      return x == rhs.x && y == rhs.y;
+    }
+
+    bool Validate() const {
+      return x >= 0.0 && x <= 1.0 && y >= 0.0 && y <= 1.0;
+    }
+
+    // xy chromaticity coordinates must be calculated as specified in ISO
+    // 11664-3:2012 Section 7, and must be specified with four decimal places.
+    // The x coordinate should be in the range [0.0001, 0.7400] and the y
+    // coordinate should be in the range [0.0001, 0.8400]. Valid range [0.0000,
+    // 1.0000].
+    float x = 0.0f;
+    float y = 0.0f;
+  };
+
+  HdrMasteringMetadata();
+
+  bool operator==(const HdrMasteringMetadata& rhs) const {
+    return ((primary_r == rhs.primary_r) && (primary_g == rhs.primary_g) &&
+            (primary_b == rhs.primary_b) && (white_point == rhs.white_point) &&
+            (luminance_max == rhs.luminance_max) &&
+            (luminance_min == rhs.luminance_min));
+  }
+
+  bool Validate() const {
+    return luminance_max >= 0.0 && luminance_max <= 20000.0 &&
+           luminance_min >= 0.0 && luminance_min <= 5.0 &&
+           primary_r.Validate() && primary_g.Validate() &&
+           primary_b.Validate() && white_point.Validate();
+  }
+
+  // The nominal primaries of the mastering display.
+  Chromaticity primary_r;
+  Chromaticity primary_g;
+  Chromaticity primary_b;
+
+  // The nominal chromaticity of the white point of the mastering display.
+  Chromaticity white_point;
+
+  // The nominal maximum display luminance of the mastering display. Specified
+  // in the unit candela/m2. The value should be in the range [5, 10000] with
+  // zero decimal places. Valid range [0, 20000].
+  float luminance_max = 0.0f;
+
+  // The nominal minimum display luminance of the mastering display. Specified
+  // in the unit candela/m2. The value should be in the range [0.0001, 5.0000]
+  // with four decimal places. Valid range [0.0000, 5.0000].
+  float luminance_min = 0.0f;
+};
+
+// High dynamic range (HDR) metadata common for HDR10 and WebM/VP9-based HDR
+// formats. This struct replicates the HDRMetadata struct defined in
+// https://cs.chromium.org/chromium/src/media/base/hdr_metadata.h
+struct HdrMetadata {
+  HdrMetadata();
+
+  bool operator==(const HdrMetadata& rhs) const {
+    return (
+        (max_content_light_level == rhs.max_content_light_level) &&
+        (max_frame_average_light_level == rhs.max_frame_average_light_level) &&
+        (mastering_metadata == rhs.mastering_metadata));
+  }
+
+  bool Validate() const {
+    return max_content_light_level >= 0 && max_content_light_level <= 20000 &&
+           max_frame_average_light_level >= 0 &&
+           max_frame_average_light_level <= 20000 &&
+           mastering_metadata.Validate();
+  }
+
+  HdrMasteringMetadata mastering_metadata;
+  // Max content light level (CLL), i.e. maximum brightness level present in the
+  // stream, in nits. 1 nit = 1 candela/m2. Valid range [0, 20000].
+  int max_content_light_level = 0;
+  // Max frame-average light level (FALL), i.e. maximum average brightness of
+  // the brightest frame in the stream, in nits. Valid range [0, 20000].
+  int max_frame_average_light_level = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // API_VIDEO_HDR_METADATA_H_
diff --git a/webrtc/api/video/video_content_type.cc b/webrtc/api/video/video_content_type.cc
new file mode 100644
index 0000000..9ba3ece
--- /dev/null
+++ b/webrtc/api/video/video_content_type.cc
@@ -0,0 +1,93 @@
+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/video/video_content_type.h"
+
+// VideoContentType stored as a single byte, which is sent over the network.
+// Structure:
+//
+//  0 1 2 3 4 5 6 7
+// +---------------+
+// |r r e e e s s c|
+//
+// where:
+// r - reserved bits.
+// e - 3-bit number of an experiment group counted from 1. 0 means there's no
+// experiment ongoing.
+// s - 2-bit simulcast stream id or spatial layer, counted from 1. 0 means that
+// no simulcast information is set.
+// c - content type. 0 means real-time video, 1 means screenshare.
+//
+
+namespace webrtc {
+namespace videocontenttypehelpers {
+
+namespace {
+static constexpr uint8_t kScreenshareBitsSize = 1;
+static constexpr uint8_t kScreenshareBitsMask =
+    (1u << kScreenshareBitsSize) - 1;
+
+static constexpr uint8_t kSimulcastShift = 1;
+static constexpr uint8_t kSimulcastBitsSize = 2;
+static constexpr uint8_t kSimulcastBitsMask = ((1u << kSimulcastBitsSize) - 1)
+                                              << kSimulcastShift;  // 0b00000110
+
+static constexpr uint8_t kExperimentShift = 3;
+static constexpr uint8_t kExperimentBitsSize = 3;
+static constexpr uint8_t kExperimentBitsMask =
+    ((1u << kExperimentBitsSize) - 1) << kExperimentShift;  // 0b00111000
+
+static constexpr uint8_t kTotalBitsSize =
+    kScreenshareBitsSize + kSimulcastBitsSize + kExperimentBitsSize;
+}  // namespace
+
+bool SetExperimentId(VideoContentType* content_type, uint8_t experiment_id) {
+  // Store in bits 2-4.
+  if (experiment_id >= (1 << kExperimentBitsSize))
+    return false;
+  *content_type = static_cast<VideoContentType>(
+      (static_cast<uint8_t>(*content_type) & ~kExperimentBitsMask) |
+      ((experiment_id << kExperimentShift) & kExperimentBitsMask));
+  return true;
+}
+
+bool SetSimulcastId(VideoContentType* content_type, uint8_t simulcast_id) {
+  // Store in bits 5-6.
+  if (simulcast_id >= (1 << kSimulcastBitsSize))
+    return false;
+  *content_type = static_cast<VideoContentType>(
+      (static_cast<uint8_t>(*content_type) & ~kSimulcastBitsMask) |
+      ((simulcast_id << kSimulcastShift) & kSimulcastBitsMask));
+  return true;
+}
+
+uint8_t GetExperimentId(const VideoContentType& content_type) {
+  return (static_cast<uint8_t>(content_type) & kExperimentBitsMask) >>
+         kExperimentShift;
+}
+uint8_t GetSimulcastId(const VideoContentType& content_type) {
+  return (static_cast<uint8_t>(content_type) & kSimulcastBitsMask) >>
+         kSimulcastShift;
+}
+
+bool IsScreenshare(const VideoContentType& content_type) {
+  return (static_cast<uint8_t>(content_type) & kScreenshareBitsMask) > 0;
+}
+
+bool IsValidContentType(uint8_t value) {
+  // Any 6-bit value is allowed.
+  return value < (1 << kTotalBitsSize);
+}
+
+const char* ToString(const VideoContentType& content_type) {
+  return IsScreenshare(content_type) ? "screen" : "realtime";
+}
+}  // namespace videocontenttypehelpers
+}  // namespace webrtc
diff --git a/webrtc/api/video/video_content_type.h b/webrtc/api/video/video_content_type.h
new file mode 100644
index 0000000..2d38a62
--- /dev/null
+++ b/webrtc/api/video/video_content_type.h
@@ -0,0 +1,39 @@
+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_VIDEO_VIDEO_CONTENT_TYPE_H_
+#define API_VIDEO_VIDEO_CONTENT_TYPE_H_
+
+#include <stdint.h>
+
+namespace webrtc {
+
+enum class VideoContentType : uint8_t {
+  UNSPECIFIED = 0,
+  SCREENSHARE = 1,
+};
+
+namespace videocontenttypehelpers {
+bool SetExperimentId(VideoContentType* content_type, uint8_t experiment_id);
+bool SetSimulcastId(VideoContentType* content_type, uint8_t simulcast_id);
+
+uint8_t GetExperimentId(const VideoContentType& content_type);
+uint8_t GetSimulcastId(const VideoContentType& content_type);
+
+bool IsScreenshare(const VideoContentType& content_type);
+
+bool IsValidContentType(uint8_t value);
+
+const char* ToString(const VideoContentType& content_type);
+}  // namespace videocontenttypehelpers
+
+}  // namespace webrtc
+
+#endif  // API_VIDEO_VIDEO_CONTENT_TYPE_H_
diff --git a/webrtc/api/video/video_rotation.h b/webrtc/api/video/video_rotation.h
new file mode 100644
index 0000000..6a29588
--- /dev/null
+++ b/webrtc/api/video/video_rotation.h
@@ -0,0 +1,26 @@
+/*
+ *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_VIDEO_VIDEO_ROTATION_H_
+#define API_VIDEO_VIDEO_ROTATION_H_
+
+namespace webrtc {
+
+// enum for clockwise rotation.
+enum VideoRotation {
+  kVideoRotation_0 = 0,
+  kVideoRotation_90 = 90,
+  kVideoRotation_180 = 180,
+  kVideoRotation_270 = 270
+};
+
+}  // namespace webrtc
+
+#endif  // API_VIDEO_VIDEO_ROTATION_H_
diff --git a/webrtc/api/video/video_timing.cc b/webrtc/api/video/video_timing.cc
new file mode 100644
index 0000000..df1bc48
--- /dev/null
+++ b/webrtc/api/video/video_timing.cc
@@ -0,0 +1,92 @@
+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/video/video_timing.h"
+
+#include "api/array_view.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/numerics/safe_conversions.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+
+uint16_t VideoSendTiming::GetDeltaCappedMs(int64_t base_ms, int64_t time_ms) {
+  if (time_ms < base_ms) {
+    RTC_DLOG(LS_ERROR) << "Delta " << (time_ms - base_ms)
+                       << "ms expected to be positive";
+  }
+  return rtc::saturated_cast<uint16_t>(time_ms - base_ms);
+}
+
+TimingFrameInfo::TimingFrameInfo()
+    : rtp_timestamp(0),
+      capture_time_ms(-1),
+      encode_start_ms(-1),
+      encode_finish_ms(-1),
+      packetization_finish_ms(-1),
+      pacer_exit_ms(-1),
+      network_timestamp_ms(-1),
+      network2_timestamp_ms(-1),
+      receive_start_ms(-1),
+      receive_finish_ms(-1),
+      decode_start_ms(-1),
+      decode_finish_ms(-1),
+      render_time_ms(-1),
+      flags(VideoSendTiming::kNotTriggered) {}
+
+int64_t TimingFrameInfo::EndToEndDelay() const {
+  return capture_time_ms >= 0 ? decode_finish_ms - capture_time_ms : -1;
+}
+
+bool TimingFrameInfo::IsLongerThan(const TimingFrameInfo& other) const {
+  int64_t other_delay = other.EndToEndDelay();
+  return other_delay == -1 || EndToEndDelay() > other_delay;
+}
+
+bool TimingFrameInfo::operator<(const TimingFrameInfo& other) const {
+  return other.IsLongerThan(*this);
+}
+
+bool TimingFrameInfo::operator<=(const TimingFrameInfo& other) const {
+  return !IsLongerThan(other);
+}
+
+bool TimingFrameInfo::IsOutlier() const {
+  return !IsInvalid() && (flags & VideoSendTiming::kTriggeredBySize);
+}
+
+bool TimingFrameInfo::IsTimerTriggered() const {
+  return !IsInvalid() && (flags & VideoSendTiming::kTriggeredByTimer);
+}
+
+bool TimingFrameInfo::IsInvalid() const {
+  return flags == VideoSendTiming::kInvalid;
+}
+
+std::string TimingFrameInfo::ToString() const {
+  if (IsInvalid()) {
+    return "";
+  }
+
+  char buf[1024];
+  rtc::SimpleStringBuilder sb(buf);
+
+  sb << rtp_timestamp << ',' << capture_time_ms << ',' << encode_start_ms << ','
+     << encode_finish_ms << ',' << packetization_finish_ms << ','
+     << pacer_exit_ms << ',' << network_timestamp_ms << ','
+     << network2_timestamp_ms << ',' << receive_start_ms << ','
+     << receive_finish_ms << ',' << decode_start_ms << ',' << decode_finish_ms
+     << ',' << render_time_ms << ',' << IsOutlier() << ','
+     << IsTimerTriggered();
+
+  return sb.str();
+}
+
+}  // namespace webrtc
diff --git a/webrtc/api/video/video_timing.h b/webrtc/api/video/video_timing.h
new file mode 100644
index 0000000..fbd9225
--- /dev/null
+++ b/webrtc/api/video/video_timing.h
@@ -0,0 +1,129 @@
+/*
+ *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_VIDEO_VIDEO_TIMING_H_
+#define API_VIDEO_VIDEO_TIMING_H_
+
+#include <stdint.h>
+
+#include <limits>
+#include <string>
+
+namespace webrtc {
+
+// Video timing timestamps in ms counted from capture_time_ms of a frame.
+// This structure represents data sent in video-timing RTP header extension.
+struct VideoSendTiming {
+  enum TimingFrameFlags : uint8_t {
+    kNotTriggered = 0,  // Timing info valid, but not to be transmitted.
+                        // Used on send-side only.
+    kTriggeredByTimer = 1 << 0,  // Frame marked for tracing by periodic timer.
+    kTriggeredBySize = 1 << 1,   // Frame marked for tracing due to size.
+    kInvalid = std::numeric_limits<uint8_t>::max()  // Invalid, ignore!
+  };
+
+  // Returns |time_ms - base_ms| capped at max 16-bit value.
+  // Used to fill this data structure as per
+  // https://webrtc.org/experiments/rtp-hdrext/video-timing/ extension stores
+  // 16-bit deltas of timestamps from packet capture time.
+  static uint16_t GetDeltaCappedMs(int64_t base_ms, int64_t time_ms);
+
+  uint16_t encode_start_delta_ms;
+  uint16_t encode_finish_delta_ms;
+  uint16_t packetization_finish_delta_ms;
+  uint16_t pacer_exit_delta_ms;
+  uint16_t network_timestamp_delta_ms;
+  uint16_t network2_timestamp_delta_ms;
+  uint8_t flags;
+};
+
+// Used to report precise timings of a 'timing frames'. Contains all important
+// timestamps for a lifetime of that specific frame. Reported as a string via
+// GetStats(). Only frame which took the longest between two GetStats calls is
+// reported.
+struct TimingFrameInfo {
+  TimingFrameInfo();
+
+  // Returns end-to-end delay of a frame, if sender and receiver timestamps are
+  // synchronized, -1 otherwise.
+  int64_t EndToEndDelay() const;
+
+  // Returns true if current frame took longer to process than |other| frame.
+  // If other frame's clocks are not synchronized, current frame is always
+  // preferred.
+  bool IsLongerThan(const TimingFrameInfo& other) const;
+
+  // Returns true if flags are set to indicate this frame was marked for tracing
+  // due to the size being outside some limit.
+  bool IsOutlier() const;
+
+  // Returns true if flags are set to indicate this frame was marked fro tracing
+  // due to cyclic timer.
+  bool IsTimerTriggered() const;
+
+  // Returns true if the timing data is marked as invalid, in which case it
+  // should be ignored.
+  bool IsInvalid() const;
+
+  std::string ToString() const;
+
+  bool operator<(const TimingFrameInfo& other) const;
+
+  bool operator<=(const TimingFrameInfo& other) const;
+
+  uint32_t rtp_timestamp;  // Identifier of a frame.
+  // All timestamps below are in local monotonous clock of a receiver.
+  // If sender clock is not yet estimated, sender timestamps
+  // (capture_time_ms ... pacer_exit_ms) are negative values, still
+  // relatively correct.
+  int64_t capture_time_ms;          // Captrue time of a frame.
+  int64_t encode_start_ms;          // Encode start time.
+  int64_t encode_finish_ms;         // Encode completion time.
+  int64_t packetization_finish_ms;  // Time when frame was passed to pacer.
+  int64_t pacer_exit_ms;  // Time when last packet was pushed out of pacer.
+  // Two in-network RTP processor timestamps: meaning is application specific.
+  int64_t network_timestamp_ms;
+  int64_t network2_timestamp_ms;
+  int64_t receive_start_ms;   // First received packet time.
+  int64_t receive_finish_ms;  // Last received packet time.
+  int64_t decode_start_ms;    // Decode start time.
+  int64_t decode_finish_ms;   // Decode completion time.
+  int64_t render_time_ms;     // Proposed render time to insure smooth playback.
+
+  uint8_t flags;  // Flags indicating validity and/or why tracing was triggered.
+};
+
+// Minimum and maximum playout delay values from capture to render.
+// These are best effort values.
+//
+// A value < 0 indicates no change from previous valid value.
+//
+// min = max = 0 indicates that the receiver should try and render
+// frame as soon as possible.
+//
+// min = x, max = y indicates that the receiver is free to adapt
+// in the range (x, y) based on network jitter.
+struct VideoPlayoutDelay {
+  VideoPlayoutDelay() = default;
+  VideoPlayoutDelay(int min_ms, int max_ms) : min_ms(min_ms), max_ms(max_ms) {}
+  int min_ms = -1;
+  int max_ms = -1;
+
+  bool operator==(const VideoPlayoutDelay& rhs) const {
+    return min_ms == rhs.min_ms && max_ms == rhs.max_ms;
+  }
+};
+
+// TODO(bugs.webrtc.org/7660): Old name, delete after downstream use is updated.
+using PlayoutDelay = VideoPlayoutDelay;
+
+}  // namespace webrtc
+
+#endif  // API_VIDEO_VIDEO_TIMING_H_