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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.
#include "media/formats/webm/cluster_builder.h"
#include <memory>
#include <utility>
#include "base/check_op.h"
#include "media/base/data_buffer.h"
#include "media/formats/webm/webm_constants.h"
namespace media {
static const uint8_t kClusterHeader[] = {
0x1F, 0x43, 0xB6, 0x75, // CLUSTER ID
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // cluster(size = 0)
0xE7, // Timecode ID
0x88, // timecode(size=8)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // timecode value
};
static const uint8_t kSimpleBlockHeader[] = {
0xA3, // SimpleBlock ID
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // SimpleBlock(size = 0)
};
static const uint8_t kBlockGroupHeader[] = {
0xA0, // BlockGroup ID
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // BlockGroup(size = 0)
0x9B, // BlockDuration ID
0x88, // BlockDuration(size = 8)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // duration
0xA1, // Block ID
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Block(size = 0)
};
static const uint8_t kBlockGroupHeaderWithoutBlockDuration[] = {
0xA0, // BlockGroup ID
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // BlockGroup(size = 0)
0xA1, // Block ID
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Block(size = 0)
};
static const uint8_t kBlockGroupReferenceBlock[] = {
0xFB, // ReferenceBlock ID
0x81, 0x00, // ReferenceBlock (size=1, value=0)
};
enum {
kClusterSizeOffset = 4,
kClusterTimecodeOffset = 14,
kSimpleBlockSizeOffset = 1,
kBlockGroupSizeOffset = 1,
kBlockGroupWithoutBlockDurationBlockSizeOffset = 10,
kBlockGroupDurationOffset = 11,
kBlockGroupBlockSizeOffset = 20,
kInitialBufferSize = 32768,
};
Cluster::Cluster(std::unique_ptr<uint8_t[]> data, int size)
: data_(std::move(data)), size_(size) {}
Cluster::~Cluster() = default;
ClusterBuilder::ClusterBuilder() { Reset(); }
ClusterBuilder::~ClusterBuilder() = default;
void ClusterBuilder::SetClusterTimecode(int64_t cluster_timecode) {
DCHECK_EQ(cluster_timecode_, -1);
cluster_timecode_ = cluster_timecode;
// Write the timecode into the header.
uint8_t* buf = buffer_.get() + kClusterTimecodeOffset;
for (int i = 7; i >= 0; --i) {
buf[i] = cluster_timecode & 0xff;
cluster_timecode >>= 8;
}
}
void ClusterBuilder::AddSimpleBlock(int track_num,
int64_t timecode,
int flags,
const uint8_t* data,
int size) {
int block_size = size + 4;
int bytes_needed = sizeof(kSimpleBlockHeader) + block_size;
if (bytes_needed > (buffer_size_ - bytes_used_))
ExtendBuffer(bytes_needed);
uint8_t* buf = buffer_.get() + bytes_used_;
int block_offset = bytes_used_;
memcpy(buf, kSimpleBlockHeader, sizeof(kSimpleBlockHeader));
UpdateUInt64(block_offset + kSimpleBlockSizeOffset, block_size);
buf += sizeof(kSimpleBlockHeader);
WriteBlock(buf, track_num, timecode, flags, data, size);
bytes_used_ += bytes_needed;
}
void ClusterBuilder::AddBlockGroup(int track_num,
int64_t timecode,
int duration,
int flags,
bool is_key_frame,
const uint8_t* data,
int size) {
AddBlockGroupInternal(track_num, timecode, true, duration, flags,
is_key_frame, data, size);
}
void ClusterBuilder::AddBlockGroupWithoutBlockDuration(int track_num,
int64_t timecode,
int flags,
bool is_key_frame,
const uint8_t* data,
int size) {
AddBlockGroupInternal(track_num, timecode, false, 0, flags, is_key_frame,
data, size);
}
void ClusterBuilder::AddBlockGroupInternal(int track_num,
int64_t timecode,
bool include_block_duration,
int duration,
int flags,
bool is_key_frame,
const uint8_t* data,
int size) {
int block_size = size + 4;
int bytes_needed = block_size;
if (include_block_duration) {
bytes_needed += sizeof(kBlockGroupHeader);
} else {
bytes_needed += sizeof(kBlockGroupHeaderWithoutBlockDuration);
}
if (!is_key_frame) {
bytes_needed += sizeof(kBlockGroupReferenceBlock);
}
int block_group_size = bytes_needed - 9;
if (bytes_needed > (buffer_size_ - bytes_used_))
ExtendBuffer(bytes_needed);
uint8_t* buf = buffer_.get() + bytes_used_;
int block_group_offset = bytes_used_;
if (include_block_duration) {
memcpy(buf, kBlockGroupHeader, sizeof(kBlockGroupHeader));
UpdateUInt64(block_group_offset + kBlockGroupDurationOffset, duration);
UpdateUInt64(block_group_offset + kBlockGroupBlockSizeOffset, block_size);
buf += sizeof(kBlockGroupHeader);
} else {
memcpy(buf, kBlockGroupHeaderWithoutBlockDuration,
sizeof(kBlockGroupHeaderWithoutBlockDuration));
UpdateUInt64(
block_group_offset + kBlockGroupWithoutBlockDurationBlockSizeOffset,
block_size);
buf += sizeof(kBlockGroupHeaderWithoutBlockDuration);
}
UpdateUInt64(block_group_offset + kBlockGroupSizeOffset, block_group_size);
// Make sure the 4 most-significant bits are 0.
// http://www.matroska.org/technical/specs/index.html#block_structure
flags &= 0x0f;
WriteBlock(buf, track_num, timecode, flags, data, size);
buf += size + 4;
if (!is_key_frame) {
memcpy(buf, kBlockGroupReferenceBlock, sizeof(kBlockGroupReferenceBlock));
}
bytes_used_ += bytes_needed;
}
void ClusterBuilder::WriteBlock(uint8_t* buf,
int track_num,
int64_t timecode,
int flags,
const uint8_t* data,
int size) {
DCHECK_GE(track_num, 0);
DCHECK_LE(track_num, 126);
DCHECK_GE(flags, 0);
DCHECK_LE(flags, 0xff);
DCHECK(data);
DCHECK_GE(size, 0); // For testing, allow 0-byte coded frames.
DCHECK_NE(cluster_timecode_, -1);
int64_t timecode_delta = timecode - cluster_timecode_;
DCHECK_GE(timecode_delta, -32768);
DCHECK_LE(timecode_delta, 32767);
buf[0] = 0x80 | (track_num & 0x7F);
buf[1] = (timecode_delta >> 8) & 0xff;
buf[2] = timecode_delta & 0xff;
buf[3] = flags & 0xff;
memcpy(buf + 4, data, size);
}
std::unique_ptr<Cluster> ClusterBuilder::Finish() {
DCHECK_NE(cluster_timecode_, -1);
UpdateUInt64(kClusterSizeOffset, bytes_used_ - (kClusterSizeOffset + 8));
std::unique_ptr<Cluster> ret(new Cluster(std::move(buffer_), bytes_used_));
Reset();
return ret;
}
std::unique_ptr<Cluster> ClusterBuilder::FinishWithUnknownSize() {
DCHECK_NE(cluster_timecode_, -1);
UpdateUInt64(kClusterSizeOffset, kWebMUnknownSize);
std::unique_ptr<Cluster> ret(new Cluster(std::move(buffer_), bytes_used_));
Reset();
return ret;
}
void ClusterBuilder::Reset() {
buffer_size_ = kInitialBufferSize;
buffer_.reset(new uint8_t[buffer_size_]);
memcpy(buffer_.get(), kClusterHeader, sizeof(kClusterHeader));
bytes_used_ = sizeof(kClusterHeader);
cluster_timecode_ = -1;
}
void ClusterBuilder::ExtendBuffer(int bytes_needed) {
int new_buffer_size = 2 * buffer_size_;
while ((new_buffer_size - bytes_used_) < bytes_needed)
new_buffer_size *= 2;
std::unique_ptr<uint8_t[]> new_buffer(new uint8_t[new_buffer_size]);
memcpy(new_buffer.get(), buffer_.get(), bytes_used_);
buffer_ = std::move(new_buffer);
buffer_size_ = new_buffer_size;
}
void ClusterBuilder::UpdateUInt64(int offset, int64_t value) {
DCHECK_LE(offset + 7, buffer_size_);
uint8_t* buf = buffer_.get() + offset;
// Fill the last 7 bytes of size field in big-endian order.
for (int i = 7; i > 0; i--) {
buf[i] = value & 0xff;
value >>= 8;
}
}
} // namespace media
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