// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/formats/mp2t/ts_section_pes.h"
#include <memory>
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "media/base/bit_reader.h"
#include "media/base/byte_queue.h"
#include "media/base/stream_parser_buffer.h"
#include "media/base/timestamp_constants.h"
#include "media/formats/mp2t/es_parser.h"
#include "media/formats/mp2t/mp2t_common.h"
#include "media/formats/mp2t/timestamp_unroller.h"
static const int kPesStartCode = 0x000001;
static bool IsTimestampSectionValid(int64_t timestamp_section) {
// |pts_section| has 40 bits:
// - starting with either '0010' or '0011' or '0001'
// - and ending with a marker bit.
// See ITU H.222 standard - PES section.
// Verify that all the marker bits are set to one.
return ((timestamp_section & 0x1) != 0) &&
((timestamp_section & 0x10000) != 0) &&
((timestamp_section & 0x100000000) != 0);
}
static int64_t ConvertTimestampSectionToTimestamp(int64_t timestamp_section) {
return (((timestamp_section >> 33) & 0x7) << 30) |
(((timestamp_section >> 17) & 0x7fff) << 15) |
(((timestamp_section >> 1) & 0x7fff) << 0);
}
namespace media {
namespace mp2t {
TsSectionPes::TsSectionPes(std::unique_ptr<EsParser> es_parser,
TimestampUnroller* timestamp_unroller)
: es_parser_(es_parser.release()),
wait_for_pusi_(true),
timestamp_unroller_(timestamp_unroller) {
DCHECK(es_parser_);
DCHECK(timestamp_unroller_);
}
TsSectionPes::~TsSectionPes() {
}
bool TsSectionPes::Parse(bool payload_unit_start_indicator,
base::span<const uint8_t> buf) {
// Ignore partial PES.
if (wait_for_pusi_ && !payload_unit_start_indicator)
return true;
bool parse_result = true;
if (payload_unit_start_indicator) {
// Try emitting a packet since we might have a pending PES packet
// with an undefined size.
// In this case, a unit is emitted when the next unit is coming.
int raw_pes_size;
const uint8_t* raw_pes;
pes_byte_queue_.Peek(&raw_pes, &raw_pes_size);
if (raw_pes_size > 0)
parse_result = Emit(true);
// Reset the state.
ResetPesState();
// Update the state.
wait_for_pusi_ = false;
}
// Add the data to the parser state.
if (!buf.empty()) {
RCHECK(pes_byte_queue_.Push(buf));
}
// Try emitting the current PES packet.
return (parse_result && Emit(false));
}
void TsSectionPes::Flush() {
// Try emitting a packet since we might have a pending PES packet
// with an undefined size.
Emit(true);
// Flush the underlying ES parser.
es_parser_->Flush();
}
void TsSectionPes::Reset() {
ResetPesState();
es_parser_->Reset();
}
bool TsSectionPes::Emit(bool emit_for_unknown_size) {
int raw_pes_size;
const uint8_t* raw_pes;
pes_byte_queue_.Peek(&raw_pes, &raw_pes_size);
// A PES should be at least 6 bytes.
// Wait for more data to come if not enough bytes.
if (raw_pes_size < 6)
return true;
// Check whether we have enough data to start parsing.
int pes_packet_length =
(static_cast<int>(raw_pes[4]) << 8) |
(static_cast<int>(raw_pes[5]));
if ((pes_packet_length == 0 && !emit_for_unknown_size) ||
(pes_packet_length != 0 && raw_pes_size < pes_packet_length + 6)) {
// Wait for more data to come either because:
// - there are not enough bytes,
// - or the PES size is unknown and the "force emit" flag is not set.
// (PES size might be unknown for video PES packet).
return true;
}
DVLOG(LOG_LEVEL_PES) << "pes_packet_length=" << pes_packet_length;
// Parse the packet.
bool parse_result = ParseInternal(raw_pes, raw_pes_size);
// Reset the state.
ResetPesState();
return parse_result;
}
bool TsSectionPes::ParseInternal(const uint8_t* raw_pes, int raw_pes_size) {
BitReader bit_reader(raw_pes, raw_pes_size);
// Read up to the pes_packet_length (6 bytes).
int packet_start_code_prefix;
int stream_id;
int pes_packet_length;
RCHECK(bit_reader.ReadBits(24, &packet_start_code_prefix));
RCHECK(bit_reader.ReadBits(8, &stream_id));
RCHECK(bit_reader.ReadBits(16, &pes_packet_length));
RCHECK(packet_start_code_prefix == kPesStartCode);
DVLOG(LOG_LEVEL_PES) << "stream_id=" << std::hex << stream_id << std::dec;
if (pes_packet_length == 0)
pes_packet_length = bit_reader.bits_available() / 8;
// Ignore the PES for unknown stream IDs.
// See ITU H.222 Table 2-22 "Stream_id assignments"
bool is_audio_stream_id = ((stream_id & 0xe0) == 0xc0);
bool is_video_stream_id = ((stream_id & 0xf0) == 0xe0);
// According to ETSI DVB standard (ETSI TS 101 154) section 4.1.6.1
// AC-3 and DTS audio streams may have stream_id 0xbd. These streams
// have the same syntax as regular audio streams.
bool is_private_stream_1 = (stream_id == 0xbd);
if (!is_audio_stream_id && !is_video_stream_id && !is_private_stream_1) {
DVLOG(LOG_LEVEL_PES) << "Dropped TsPacket for stream_id=0x"
<< std::hex << stream_id << std::dec;
return true;
}
// Read up to "pes_header_data_length".
int dummy_2;
int PES_scrambling_control;
int PES_priority;
int data_alignment_indicator;
int copyright;
int original_or_copy;
int pts_dts_flags;
int escr_flag;
int es_rate_flag;
int dsm_trick_mode_flag;
int additional_copy_info_flag;
int pes_crc_flag;
int pes_extension_flag;
int pes_header_data_length;
RCHECK(bit_reader.ReadBits(2, &dummy_2));
RCHECK(dummy_2 == 0x2);
RCHECK(bit_reader.ReadBits(2, &PES_scrambling_control));
RCHECK(bit_reader.ReadBits(1, &PES_priority));
RCHECK(bit_reader.ReadBits(1, &data_alignment_indicator));
RCHECK(bit_reader.ReadBits(1, ©right));
RCHECK(bit_reader.ReadBits(1, &original_or_copy));
RCHECK(bit_reader.ReadBits(2, &pts_dts_flags));
RCHECK(bit_reader.ReadBits(1, &escr_flag));
RCHECK(bit_reader.ReadBits(1, &es_rate_flag));
RCHECK(bit_reader.ReadBits(1, &dsm_trick_mode_flag));
RCHECK(bit_reader.ReadBits(1, &additional_copy_info_flag));
RCHECK(bit_reader.ReadBits(1, &pes_crc_flag));
RCHECK(bit_reader.ReadBits(1, &pes_extension_flag));
RCHECK(bit_reader.ReadBits(8, &pes_header_data_length));
int pes_header_start_size = bit_reader.bits_available() / 8;
// Compute the size and the offset of the ES payload.
// "6" for the 6 bytes read before and including |pes_packet_length|.
// "3" for the 3 bytes read before and including |pes_header_data_length|.
int es_size = pes_packet_length - 3 - pes_header_data_length;
int es_offset = 6 + 3 + pes_header_data_length;
RCHECK(es_size >= 0);
RCHECK(es_offset + es_size <= raw_pes_size);
// Read the timing information section.
bool is_pts_valid = false;
bool is_dts_valid = false;
int64_t pts_section = 0;
int64_t dts_section = 0;
if (pts_dts_flags == 0x2) {
RCHECK(bit_reader.ReadBits(40, &pts_section));
RCHECK((((pts_section >> 36) & 0xf) == 0x2) &&
IsTimestampSectionValid(pts_section));
is_pts_valid = true;
}
if (pts_dts_flags == 0x3) {
RCHECK(bit_reader.ReadBits(40, &pts_section));
RCHECK(bit_reader.ReadBits(40, &dts_section));
RCHECK((((pts_section >> 36) & 0xf) == 0x3) &&
IsTimestampSectionValid(pts_section));
RCHECK((((dts_section >> 36) & 0xf) == 0x1) &&
IsTimestampSectionValid(dts_section));
is_pts_valid = true;
is_dts_valid = true;
}
// Convert and unroll the timestamps.
base::TimeDelta media_pts(kNoTimestamp);
DecodeTimestamp media_dts(kNoDecodeTimestamp);
if (is_pts_valid) {
int64_t pts = timestamp_unroller_->GetUnrolledTimestamp(
ConvertTimestampSectionToTimestamp(pts_section));
media_pts = base::Microseconds((1000 * pts) / 90);
}
if (is_dts_valid) {
int64_t dts = timestamp_unroller_->GetUnrolledTimestamp(
ConvertTimestampSectionToTimestamp(dts_section));
media_dts = DecodeTimestamp::FromMicroseconds((1000 * dts) / 90);
}
// Discard the rest of the PES packet header.
// TODO(damienv): check if some info of the PES packet header are useful.
DCHECK_EQ(bit_reader.bits_available() % 8, 0);
int pes_header_remaining_size = pes_header_data_length -
(pes_header_start_size - bit_reader.bits_available() / 8);
RCHECK(pes_header_remaining_size >= 0);
// Read the PES packet.
DVLOG(LOG_LEVEL_PES)
<< "Emit a reassembled PES:"
<< " size=" << es_size
<< " pts=" << media_pts.InMilliseconds()
<< " dts=" << media_dts.InMilliseconds()
<< " data_alignment_indicator=" << data_alignment_indicator;
return es_parser_->Parse(&raw_pes[es_offset], es_size, media_pts, media_dts);
}
void TsSectionPes::ResetPesState() {
pes_byte_queue_.Reset();
wait_for_pusi_ = true;
}
} // namespace mp2t
} // namespace media
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