1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "media/formats/mp2t/ts_section_pmt.h" 6 7 #include <map> 8 9 #include "base/logging.h" 10 #include "media/base/bit_reader.h" 11 #include "media/formats/mp2t/mp2t_common.h" 12 13 namespace media { 14 namespace mp2t { 15 16 TsSectionPmt::TsSectionPmt(const RegisterPesCb& register_pes_cb) 17 : register_pes_cb_(register_pes_cb) { 18 } 19 20 TsSectionPmt::~TsSectionPmt() { 21 } 22 23 bool TsSectionPmt::ParsePsiSection(BitReader* bit_reader) { 24 // Read up to |last_section_number|. 25 int table_id; 26 int section_syntax_indicator; 27 int dummy_zero; 28 int reserved; 29 int section_length; 30 int program_number; 31 int version_number; 32 int current_next_indicator; 33 int section_number; 34 int last_section_number; 35 RCHECK(bit_reader->ReadBits(8, &table_id)); 36 RCHECK(bit_reader->ReadBits(1, §ion_syntax_indicator)); 37 RCHECK(bit_reader->ReadBits(1, &dummy_zero)); 38 RCHECK(bit_reader->ReadBits(2, &reserved)); 39 RCHECK(bit_reader->ReadBits(12, §ion_length)); 40 int section_start_marker = bit_reader->bits_available() / 8; 41 42 RCHECK(bit_reader->ReadBits(16, &program_number)); 43 RCHECK(bit_reader->ReadBits(2, &reserved)); 44 RCHECK(bit_reader->ReadBits(5, &version_number)); 45 RCHECK(bit_reader->ReadBits(1, ¤t_next_indicator)); 46 RCHECK(bit_reader->ReadBits(8, §ion_number)); 47 RCHECK(bit_reader->ReadBits(8, &last_section_number)); 48 49 // Perform a few verifications: 50 // - table ID should be 2 for a PMT. 51 // - section_syntax_indicator should be one. 52 // - section length should not exceed 1021. 53 RCHECK(table_id == 0x2); 54 RCHECK(section_syntax_indicator); 55 RCHECK(!dummy_zero); 56 RCHECK(section_length <= 1021); 57 RCHECK(section_number == 0); 58 RCHECK(last_section_number == 0); 59 60 // TODO(damienv): 61 // Verify that there is no mismatch between the program number 62 // and the program number that was provided in a PAT for the current PMT. 63 64 // Read the end of the fixed length section. 65 int pcr_pid; 66 int program_info_length; 67 RCHECK(bit_reader->ReadBits(3, &reserved)); 68 RCHECK(bit_reader->ReadBits(13, &pcr_pid)); 69 RCHECK(bit_reader->ReadBits(4, &reserved)); 70 RCHECK(bit_reader->ReadBits(12, &program_info_length)); 71 RCHECK(program_info_length < 1024); 72 73 // Read the program info descriptor. 74 // TODO(damienv): check wether any of the descriptors could be useful. 75 // Defined in section 2.6 of ISO-13818. 76 RCHECK(bit_reader->SkipBits(8 * program_info_length)); 77 78 // Read the ES description table. 79 // The end of the PID map if 4 bytes away from the end of the section 80 // (4 bytes = size of the CRC). 81 int pid_map_end_marker = section_start_marker - section_length + 4; 82 std::map<int, int> pid_map; 83 while (bit_reader->bits_available() > 8 * pid_map_end_marker) { 84 int stream_type; 85 int reserved; 86 int pid_es; 87 int es_info_length; 88 RCHECK(bit_reader->ReadBits(8, &stream_type)); 89 RCHECK(bit_reader->ReadBits(3, &reserved)); 90 RCHECK(bit_reader->ReadBits(13, &pid_es)); 91 RCHECK(bit_reader->ReadBits(4, &reserved)); 92 RCHECK(bit_reader->ReadBits(12, &es_info_length)); 93 94 // Do not register the PID right away. 95 // Wait for the end of the section to be fully parsed 96 // to make sure there is no error. 97 pid_map.insert(std::pair<int, int>(pid_es, stream_type)); 98 99 // Read the ES info descriptors. 100 // TODO(damienv): check wether any of the descriptors could be useful. 101 // Defined in section 2.6 of ISO-13818. 102 RCHECK(bit_reader->SkipBits(8 * es_info_length)); 103 } 104 105 // Read the CRC. 106 int crc32; 107 RCHECK(bit_reader->ReadBits(32, &crc32)); 108 109 // Once the PMT has been proved to be correct, register the PIDs. 110 for (std::map<int, int>::iterator it = pid_map.begin(); 111 it != pid_map.end(); ++it) 112 register_pes_cb_.Run(it->first, it->second); 113 114 return true; 115 } 116 117 void TsSectionPmt::ResetPsiSection() { 118 } 119 120 } // namespace mp2t 121 } // namespace media 122 123