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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/mpeg/adts_stream_parser.h"
#include <stddef.h>
#include "build/build_config.h"
#include "media/base/media_log.h"
#include "media/formats/mp4/aac.h"
#include "media/formats/mpeg/adts_constants.h"
namespace media {
constexpr uint32_t kADTSStartCodeMask = 0xfff00000;
ADTSStreamParser::ADTSStreamParser()
: MPEGAudioStreamParserBase(kADTSStartCodeMask, kCodecAAC, 0) {}
ADTSStreamParser::~ADTSStreamParser() = default;
int ADTSStreamParser::ParseFrameHeader(const uint8_t* data,
int size,
int* frame_size,
int* sample_rate,
ChannelLayout* channel_layout,
int* sample_count,
bool* metadata_frame,
std::vector<uint8_t>* extra_data) {
DCHECK(data);
DCHECK_GE(size, 0);
if (size < kADTSHeaderMinSize)
return 0;
BitReader reader(data, size);
int sync;
int version;
int layer;
int protection_absent;
int profile;
size_t sample_rate_index;
size_t channel_layout_index;
int frame_length;
size_t num_data_blocks;
int unused;
if (!reader.ReadBits(12, &sync) ||
!reader.ReadBits(1, &version) ||
!reader.ReadBits(2, &layer) ||
!reader.ReadBits(1, &protection_absent) ||
!reader.ReadBits(2, &profile) ||
!reader.ReadBits(4, &sample_rate_index) ||
!reader.ReadBits(1, &unused) ||
!reader.ReadBits(3, &channel_layout_index) ||
!reader.ReadBits(4, &unused) ||
!reader.ReadBits(13, &frame_length) ||
!reader.ReadBits(11, &unused) ||
!reader.ReadBits(2, &num_data_blocks) ||
(!protection_absent && !reader.ReadBits(16, &unused))) {
return -1;
}
DVLOG(2) << "Header data :" << std::hex << " sync 0x" << sync << " version 0x"
<< version << " layer 0x" << layer << " profile 0x" << profile
<< " sample_rate_index 0x" << sample_rate_index
<< " channel_layout_index 0x" << channel_layout_index;
const int bytes_read = reader.bits_read() / 8;
if (sync != 0xfff || layer != 0 || frame_length < bytes_read ||
sample_rate_index >= kADTSFrequencyTableSize ||
channel_layout_index >= kADTSChannelLayoutTableSize) {
if (media_log()) {
LIMITED_MEDIA_LOG(DEBUG, media_log(), adts_parse_error_limit_, 5)
<< "Invalid header data :" << std::hex << " sync 0x" << sync
<< " version 0x" << version << " layer 0x" << layer
<< " sample_rate_index 0x" << sample_rate_index
<< " channel_layout_index 0x" << channel_layout_index;
}
return -1;
}
if (sample_rate)
*sample_rate = kADTSFrequencyTable[sample_rate_index];
if (frame_size)
*frame_size = frame_length;
if (sample_count)
*sample_count = (num_data_blocks + 1) * kSamplesPerAACFrame;
if (channel_layout)
*channel_layout = kADTSChannelLayoutTable[channel_layout_index];
if (metadata_frame)
*metadata_frame = false;
if (extra_data) {
// See mp4::AAC::Parse() for details. We don't need to worry about writing
// extensions since we can't have extended ADTS by this point (it's
// explicitly rejected as invalid above).
DCHECK_NE(sample_rate_index, 15u);
// The following code is written according to ISO 14496 Part 3 Table 1.13 -
// Syntax of AudioSpecificConfig.
const uint16_t esds = (((((profile + 1) << 4) + sample_rate_index) << 4) +
channel_layout_index)
<< 3;
extra_data->push_back(esds >> 8);
extra_data->push_back(esds & 0xFF);
}
return bytes_read;
}
} // namespace media
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