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// Copyright 2021 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/dts/dts_util.h"
#include "base/logging.h"
#include "base/stl_util.h"
#include "media/base/bit_reader.h"
#include "media/formats/dts/dts_stream_parser.h"
namespace media {
namespace dts {
namespace {
// Match a 32-bit sync word with the content in the buffer.
bool MatchSyncWord(const uint8_t* data, uint32_t sync_word) {
return data[0] == static_cast<uint8_t>(sync_word >> 24) &&
data[1] == static_cast<uint8_t>(sync_word >> 16) &&
data[2] == static_cast<uint8_t>(sync_word >> 8) &&
data[3] == static_cast<uint8_t>(sync_word);
}
// Search for the next sync word 0x7ffe8001.
const uint8_t* FindNextSyncWord(const uint8_t* begin,
const uint8_t* end,
uint32_t sync_word) {
DCHECK(begin);
DCHECK(end);
DCHECK_LE(begin, end);
const int sync_word_len_less_one = 3;
const uint8_t* current = begin;
const uint8_t first_sync_byte = static_cast<uint8_t>(sync_word >> 24);
while (current && (current < end - sync_word_len_less_one)) {
if (MatchSyncWord(current, sync_word)) {
if (current != begin)
DVLOG(2) << __func__ << " skip " << current - begin << " bytes.";
return current;
}
++current;
current = static_cast<const uint8_t*>(
memchr(current, first_sync_byte, end - current));
}
return nullptr;
}
} // namespace
// Returns the total number of audio samples in the given buffer,
// which could contain several complete DTS sync frames.
// The parameter AudioCodec is for future samplecount support for DTSHD and
// DTSX bitstreams.
int ParseTotalSampleCount(const uint8_t* data,
size_t size,
AudioCodec dts_codec_type) {
if (!data)
return 0;
uint32_t sync_word = 0;
uint32_t header_size = 0;
// Switch statement used here for future expansion to support
// other DTS audio types
switch (dts_codec_type) {
case AudioCodec::kDTS:
sync_word = DTSStreamParser::kDTSCoreSyncWord;
header_size = DTSStreamParser::kDTSCoreHeaderSizeInBytes;
break;
default:
sync_word = 0;
header_size = 0;
}
if (size < header_size)
return 0;
DTSStreamParser parser;
const uint8_t* dend = data + size;
const uint8_t* current = FindNextSyncWord(data, dend, sync_word);
int total_sample_count = 0;
while (current && (dend > current + header_size)) {
int frame_size;
int sample_count;
int bytes_processed =
parser.ParseFrameHeader(current, dend - current, &frame_size, nullptr,
nullptr, &sample_count, nullptr, nullptr);
if ((bytes_processed > 0) && (frame_size > 0) && (sample_count > 0)) {
current += frame_size;
if (current > dend) {
DVLOG(2) << __func__ << " Incomplete frame, missing " << current - dend
<< " bytes.";
break;
}
total_sample_count += sample_count;
} else {
DVLOG(2)
<< __func__
<< " Invalid frame, skip 1 byte to find next synchronization word.";
current++;
}
current = FindNextSyncWord(current, dend, sync_word);
}
return total_sample_count;
}
} // namespace dts
} // namespace media
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