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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_BASE_AUDIO_BUFFER_CONVERTER_H_
#define MEDIA_BASE_AUDIO_BUFFER_CONVERTER_H_
#include <memory>
#include "base/containers/circular_deque.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/audio_buffer.h"
#include "media/base/audio_converter.h"
#include "media/base/audio_parameters.h"
#include "media/base/audio_timestamp_helper.h"
#include "media/base/media_export.h"
namespace media {
class AudioBus;
// Takes AudioBuffers in any format and uses an AudioConverter to convert them
// to a common format (usually the hardware output format).
class MEDIA_EXPORT AudioBufferConverter : public AudioConverter::InputCallback {
public:
explicit AudioBufferConverter(const AudioParameters& output_params);
~AudioBufferConverter() override;
void AddInput(const scoped_refptr<AudioBuffer>& buffer);
// Is an output buffer available via GetNextBuffer()?
bool HasNextBuffer();
// This should only be called this is HasNextBuffer() returns true.
scoped_refptr<AudioBuffer> GetNextBuffer();
// Reset internal state.
void Reset();
// Reset internal timestamp state. Upon the next AddInput() call, our base
// timestamp will be set to match the input buffer.
void ResetTimestampState();
int input_buffer_size_for_testing() const {
return input_params_.frames_per_buffer();
}
int input_frames_left_for_testing() const {
return input_frames_;
}
private:
// Callback to provide data to the AudioConverter
double ProvideInput(AudioBus* audio_bus, uint32_t frames_delayed) override;
// Reset the converter in response to a configuration change.
void ResetConverter(const scoped_refptr<AudioBuffer>& input_buffer);
// Perform conversion if we have enough data.
void ConvertIfPossible();
// Flush remaining output
void Flush();
// The output parameters.
AudioParameters output_params_;
// The current input parameters (we cache these to detect configuration
// changes, so we know when to reset the AudioConverter).
AudioParameters input_params_;
using BufferQueue = base::circular_deque<scoped_refptr<AudioBuffer>>;
// Queued up inputs (there will never be all that much data stored here, as
// soon as there's enough here to produce an output buffer we will do so).
BufferQueue queued_inputs_;
// Offset into the front element of |queued_inputs_|. A ProvideInput() call
// doesn't necessarily always consume an entire buffer.
int last_input_buffer_offset_;
// Buffer of output frames, to be returned by GetNextBuffer().
BufferQueue queued_outputs_;
// How many frames of input we have in |queued_inputs_|.
int input_frames_;
// Input frames in the AudioConverter's internal buffers.
double buffered_input_frames_;
// Ratio of sample rates, in/out.
double io_sample_rate_ratio_;
// Computes timestamps in terms of the output sample rate.
AudioTimestampHelper timestamp_helper_;
// Are we flushing everything, without regard for providing AudioConverter
// full AudioBuses in ProvideInput()?
bool is_flushing_;
// Pool to avoid thrashing memory when allocating AudioBuffers.
scoped_refptr<AudioBufferMemoryPool> pool_;
// The AudioConverter which does the real work here.
std::unique_ptr<AudioConverter> audio_converter_;
};
} // namespace media
#endif // MEDIA_BASE_AUDIO_BUFFER_CONVERTER_H_
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