197 lines
6.3 KiB
C++
197 lines
6.3 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include <packager/media/formats/mp2t/ts_section_pmt.h>
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#include <vector>
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#include <absl/log/log.h>
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#include <packager/media/base/bit_reader.h>
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#include <packager/media/formats/mp2t/mp2t_common.h>
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#include <packager/media/formats/mp2t/ts_audio_type.h>
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#include <packager/media/formats/mp2t/ts_stream_type.h>
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namespace shaka {
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namespace media {
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namespace mp2t {
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namespace {
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const int kISO639LanguageDescriptor = 0x0A;
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const int kMaximumBitrateDescriptor = 0x0E;
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const int kTeletextDescriptor = 0x56;
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const int kSubtitlingDescriptor = 0x59;
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} // namespace
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TsSectionPmt::TsSectionPmt(const RegisterPesCb& register_pes_cb)
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: register_pes_cb_(register_pes_cb) {
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}
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TsSectionPmt::~TsSectionPmt() {
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}
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bool TsSectionPmt::ParsePsiSection(BitReader* bit_reader) {
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// Read up to |last_section_number|.
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int table_id;
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int section_syntax_indicator;
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int dummy_zero;
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int reserved;
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int section_length;
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int program_number;
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int version_number;
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int current_next_indicator;
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int section_number;
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int last_section_number;
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RCHECK(bit_reader->ReadBits(8, &table_id));
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RCHECK(bit_reader->ReadBits(1, §ion_syntax_indicator));
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RCHECK(bit_reader->ReadBits(1, &dummy_zero));
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RCHECK(bit_reader->ReadBits(2, &reserved));
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RCHECK(bit_reader->ReadBits(12, §ion_length));
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int section_start_marker = static_cast<int>(bit_reader->bits_available()) / 8;
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RCHECK(bit_reader->ReadBits(16, &program_number));
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RCHECK(bit_reader->ReadBits(2, &reserved));
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RCHECK(bit_reader->ReadBits(5, &version_number));
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RCHECK(bit_reader->ReadBits(1, ¤t_next_indicator));
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RCHECK(bit_reader->ReadBits(8, §ion_number));
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RCHECK(bit_reader->ReadBits(8, &last_section_number));
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// Perform a few verifications:
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// - table ID should be 2 for a PMT.
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// - section_syntax_indicator should be one.
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// - section length should not exceed 1021.
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RCHECK(table_id == 0x2);
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RCHECK(section_syntax_indicator);
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RCHECK(!dummy_zero);
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RCHECK(section_length <= 1021);
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RCHECK(section_number == 0);
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RCHECK(last_section_number == 0);
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// Read the end of the fixed length section.
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int pcr_pid;
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int program_info_length;
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RCHECK(bit_reader->ReadBits(3, &reserved));
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RCHECK(bit_reader->ReadBits(13, &pcr_pid));
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RCHECK(bit_reader->ReadBits(4, &reserved));
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RCHECK(bit_reader->ReadBits(12, &program_info_length));
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RCHECK(program_info_length < 1024);
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// Read the program info descriptor.
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// Defined in section 2.6 of ISO-13818.
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RCHECK(bit_reader->SkipBits(8 * program_info_length));
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// Read the ES description table.
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// The end of the PID map if 4 bytes away from the end of the section
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// (4 bytes = size of the CRC).
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int pid_map_end_marker = section_start_marker - section_length + 4;
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struct Info {
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int pid_es;
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TsStreamType stream_type;
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const uint8_t* descriptor;
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size_t descriptor_length;
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std::string lang;
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uint32_t max_bitrate;
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TsAudioType audio_type;
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};
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std::vector<Info> pid_info;
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while (static_cast<int>(bit_reader->bits_available()) >
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8 * pid_map_end_marker) {
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TsStreamType stream_type;
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int pid_es;
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size_t es_info_length;
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RCHECK(bit_reader->ReadBits(8, &stream_type));
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RCHECK(bit_reader->SkipBits(3)); // reserved
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RCHECK(bit_reader->ReadBits(13, &pid_es));
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RCHECK(bit_reader->ReadBits(4, &reserved));
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RCHECK(bit_reader->ReadBits(12, &es_info_length));
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const uint8_t* descriptor = bit_reader->current_byte_ptr();
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// Do not register the PID right away.
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// Wait for the end of the section to be fully parsed
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// to make sure there is no error.
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pid_info.push_back({pid_es, stream_type, descriptor, es_info_length, "", 0,
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TsAudioType::kUndefined});
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// Read the ES info descriptors.
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// Defined in section 2.6 of ISO-13818.
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uint8_t descriptor_tag;
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uint8_t descriptor_length;
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while (es_info_length) {
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RCHECK(bit_reader->ReadBits(8, &descriptor_tag));
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RCHECK(bit_reader->ReadBits(8, &descriptor_length));
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es_info_length -= 2;
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// See ETSI EN 300 468 Section 6.1
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if (stream_type == TsStreamType::kPesPrivateData) {
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switch (descriptor_tag) {
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case kTeletextDescriptor:
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pid_info.back().stream_type = TsStreamType::kTeletextSubtitles;
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break;
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case kSubtitlingDescriptor:
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pid_info.back().stream_type = TsStreamType::kDvbSubtitles;
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break;
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default:
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break;
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}
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} else if (descriptor_tag == kISO639LanguageDescriptor &&
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descriptor_length >= 4) {
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// See section 2.6.19 of ISO-13818
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// Descriptor can contain 0..N language defintions,
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// we process only the first one
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RCHECK(es_info_length >= 4);
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char lang[3];
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RCHECK(bit_reader->ReadBits(8, &lang[0])); // ISO_639_language_code
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RCHECK(bit_reader->ReadBits(8, &lang[1]));
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RCHECK(bit_reader->ReadBits(8, &lang[2]));
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RCHECK(bit_reader->ReadBits(8, &pid_info.back().audio_type));
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pid_info.back().lang = std::string(lang, 3);
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es_info_length -= 4;
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descriptor_length -= 4;
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} else if (descriptor_tag == kMaximumBitrateDescriptor &&
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descriptor_length >= 3) {
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// See section 2.6.25 of ISO-13818
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RCHECK(es_info_length >= 3);
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uint32_t max_bitrate;
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RCHECK(bit_reader->SkipBits(2)); // reserved
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RCHECK(bit_reader->ReadBits(22, &max_bitrate));
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// maximum bitrate is stored in units of 50 bytes per second
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pid_info.back().max_bitrate = 50 * 8 * max_bitrate;
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es_info_length -= 3;
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descriptor_length -= 3;
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}
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RCHECK(bit_reader->SkipBits(8 * descriptor_length));
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es_info_length -= descriptor_length;
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}
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RCHECK(bit_reader->SkipBytes(es_info_length));
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}
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// Read the CRC.
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int crc32;
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RCHECK(bit_reader->ReadBits(32, &crc32));
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// Once the PMT has been proved to be correct, register the PIDs.
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for (auto& info : pid_info) {
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register_pes_cb_(info.pid_es, info.stream_type, info.max_bitrate, info.lang,
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info.audio_type, info.descriptor, info.descriptor_length);
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}
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return true;
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}
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void TsSectionPmt::ResetPsiSection() {
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}
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} // namespace mp2t
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} // namespace media
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} // namespace shaka
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