program_map_table_writer.cc

// Copyright 2016 Google LLC. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
 
#include <packager/media/formats/mp2t/program_map_table_writer.h>
 
#include <algorithm>
#include <limits>
 
#include <absl/log/check.h>
#include <absl/log/log.h>
 
#include <packager/media/base/buffer_writer.h>
#include <packager/media/base/fourccs.h>
#include <packager/media/codecs/hls_audio_util.h>
#include <packager/media/formats/mp2t/ts_packet_writer_util.h>
#include <packager/media/formats/mp2t/ts_stream_type.h>
 
namespace shaka {
namespace media {
namespace mp2t {
 
namespace {
 
// Values for version. Only 0 and 1 are necessary for the implementation.
const int kVersion0 = 0;
const int kVersion1 = 1;
 
// Values for current_next_indicator.
const int kCurrent = 1;
const int kNext= 0;
 
// Program number is 16 bits but 8 bits is sufficient.
const uint8_t kProgramNumber = 0x01;
const uint8_t kProgramMapTableId = 0x02;
 
// Table for CRC32/MPEG2.
const uint32_t kCrcTable[] = {
    0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
    0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
    0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
    0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
    0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
    0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
    0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
    0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
    0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
    0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
    0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
    0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
    0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
    0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
    0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
    0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
    0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
    0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
    0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
    0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
    0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
    0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
    0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
    0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
    0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
    0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
    0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
    0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
    0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
    0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
    0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
    0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
    0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
    0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
    0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
    0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
    0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
    0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
    0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
    0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
    0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
    0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
    0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
    0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
    0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
    0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
    0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
    0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
    0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
    0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
    0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
    0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
    0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
    0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
    0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
    0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
    0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
    0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
    0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
    0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
    0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
    0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
    0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
    0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4,
};
 
// Note there are dozens of CRCs. This is one of them.
// http://reveng.sourceforge.net/crc-catalogue/all.htm
uint32_t Crc32Mpeg2(const uint8_t* data, size_t data_size) {
  uint32_t crc = 0xFFFFFFFF;
  for (size_t i = 0; i < data_size; ++i) {
    crc = kCrcTable[((crc >> 24) ^ data[i]) & 0xFF] ^ (crc << 8);
  }
  return crc;
}
 
void WritePmtToBuffer(const uint8_t* pmt,
                      size_t pmt_size,
                      ContinuityCounter* continuity_counter,
                      BufferWriter* writer) {
  const bool kPayloadUnitStartIndicator = true;
  const bool kHasPcr = true;
  const uint64_t kAnyPcrBase = 0;
  WritePayloadToBufferWriter(pmt, pmt_size, kPayloadUnitStartIndicator,
                             ProgramMapTableWriter::kPmtPid, !kHasPcr,
                             kAnyPcrBase, continuity_counter, writer);
}
 
void WritePrivateDataIndicatorDescriptor(FourCC fourcc, BufferWriter* output) {
  const uint8_t kPrivateDataIndicatorDescriptor = 15;
  output->AppendInt(kPrivateDataIndicatorDescriptor);
  output->AppendInt(static_cast<uint8_t>(sizeof(fourcc)));
  output->AppendInt(fourcc);
}
 
bool WriteRegistrationDescriptorForEncryptedAudio(Codec codec,
                                                  const uint8_t* setup_data,
                                                  size_t setup_data_size,
                                                  BufferWriter* output) {
  const uint8_t kRegistrationDescriptor = 5;
  BufferWriter audio_setup_information;
  if (!WriteAudioSetupInformation(codec, setup_data, setup_data_size,
                                  &audio_setup_information)) {
    return false;
  }
 
  const size_t registration_descriptor_size =
      audio_setup_information.Size() + sizeof(FOURCC_apad);
  if (registration_descriptor_size > std::numeric_limits<uint8_t>::max()) {
    LOG(ERROR) << "Audio setup data of size: " << setup_data_size
               << " will not fit in the descriptor.";
    return false;
  }
 
  output->AppendInt(kRegistrationDescriptor);
  output->AppendInt(static_cast<uint8_t>(registration_descriptor_size));
  output->AppendInt(FOURCC_apad);
  output->AppendBuffer(audio_setup_information);
  return true;
}
 
void WritePmtWithParameters(uint8_t stream_type,
                            int version,
                            int current_next_indicator,
                            const uint8_t* descriptors,
                            size_t descriptors_size,
                            BufferWriter* pmt) {
  DCHECK(current_next_indicator == kCurrent || current_next_indicator == kNext);
  // Body starting from program number.
  BufferWriter pmt_body;
  pmt_body.AppendInt(static_cast<uint8_t>(0x00));
  pmt_body.AppendInt(kProgramNumber);
  // resevered bits then version and current_next_indicator.
  pmt_body.AppendInt(
      static_cast<uint8_t>(0xC0 |
                           static_cast<uint8_t>(version) << 1 |
                           static_cast<uint8_t>(current_next_indicator)));
  // section number.
  pmt_body.AppendInt(static_cast<uint8_t>(0x00));
  // last section number.
  pmt_body.AppendInt(static_cast<uint8_t>(0x00));
  // first 3 bits reserved. Rest is unused bits for PCR PID.
  pmt_body.AppendInt(static_cast<uint8_t>(0xE0));
  pmt_body.AppendInt(ProgramMapTableWriter::kElementaryPid);
  // First 4 bits are reserved. Next 12 bits is program_info_length which is 0.
  pmt_body.AppendInt(static_cast<uint8_t>(0xF0));
  pmt_body.AppendInt(static_cast<uint8_t>(0x00));
 
  pmt_body.AppendInt(stream_type);
  // 3 reserved bits followed by 13 bit elementary_PID.
  pmt_body.AppendInt(static_cast<uint8_t>(0xE0));
  pmt_body.AppendInt(ProgramMapTableWriter::kElementaryPid);
 
  // 4 reserved bits followed by ES_info_length.
  pmt_body.AppendInt(static_cast<uint16_t>(0xF000 | descriptors_size));
  if (descriptors_size > 0) {
    DCHECK(descriptors);
    pmt_body.AppendArray(descriptors, descriptors_size);
  }
 
  pmt->Clear();
  // Pointer field is not really part of the PMT but it's there so that an extra
  // buffer isn't required to prepend the 0x00 byte.
  const uint8_t kPointerField = 0;
  pmt->AppendInt(kPointerField);
  pmt->AppendInt(kProgramMapTableId);
  // First four bits must be '1011'. +4 for CRC.
  pmt->AppendInt(static_cast<uint16_t>(0xB000 | (pmt_body.Size() + 4)));
  pmt->AppendBuffer(pmt_body);
 
  // Don't include the pointer field.
  const uint32_t crc = Crc32Mpeg2(pmt->Buffer() + 1, pmt->Size() - 1);
  pmt->AppendInt(crc);
}
 
}  // namespace
 
ProgramMapTableWriter::ProgramMapTableWriter(Codec codec) : codec_(codec) {}
 
bool ProgramMapTableWriter::EncryptedSegmentPmt(BufferWriter* writer) {
  if (encrypted_pmt_.Size() == 0) {
    TsStreamType stream_type;
    switch (codec_) {
      case kCodecH264:
        stream_type = TsStreamType::kEncryptedAvc;
        break;
      case kCodecAAC:
        stream_type = TsStreamType::kEncryptedAdtsAac;
        break;
      case kCodecAC3:
        stream_type = TsStreamType::kEncryptedAc3;
        break;
      case kCodecEAC3:
        stream_type = TsStreamType::kEncryptedEac3;
        break;
      default:
        LOG(ERROR) << "Codec " << codec_ << " is not supported in TS yet.";
        return false;
    }
 
    BufferWriter descriptors;
    if (!WriteDescriptors(&descriptors))
      return false;
 
    const bool has_clear_lead = clear_pmt_.Size() > 0;
    WritePmtWithParameters(static_cast<uint8_t>(stream_type),
                           has_clear_lead ? kVersion1 : kVersion0, kCurrent,
                           descriptors.Buffer(), descriptors.Size(),
                           &encrypted_pmt_);
    DCHECK_NE(encrypted_pmt_.Size(), 0u);
  }
  WritePmtToBuffer(encrypted_pmt_.Buffer(), encrypted_pmt_.Size(),
                   &continuity_counter_, writer);
  return true;
}
 
bool ProgramMapTableWriter::ClearSegmentPmt(BufferWriter* writer) {
  if (clear_pmt_.Size() == 0) {
    TsStreamType stream_type;
    switch (codec_) {
      case kCodecH264:
        stream_type = TsStreamType::kAvc;
        break;
      case kCodecAAC:
        stream_type = TsStreamType::kAdtsAac;
        break;
      case kCodecMP3:
        stream_type = TsStreamType::kMpeg1Audio;
        break;
      case kCodecAC3:
        stream_type = TsStreamType::kAc3;
        break;
      case kCodecEAC3:
        stream_type = TsStreamType::kEac3;
        break;
      default:
        LOG(ERROR) << "Codec " << codec_ << " is not supported in TS yet.";
        return false;
    }
 
    WritePmtWithParameters(static_cast<uint8_t>(stream_type), kVersion0,
                           kCurrent, nullptr, 0, &clear_pmt_);
    DCHECK_NE(clear_pmt_.Size(), 0u);
  }
  WritePmtToBuffer(clear_pmt_.Buffer(), clear_pmt_.Size(), &continuity_counter_,
                   writer);
  return true;
}
 
VideoProgramMapTableWriter::VideoProgramMapTableWriter(Codec codec)
    : ProgramMapTableWriter(codec) {}
 
bool VideoProgramMapTableWriter::WriteDescriptors(
    BufferWriter* descriptors) const {
  FourCC fourcc;
  switch (codec()) {
    case kCodecH264:
      fourcc = FOURCC_zavc;
      break;
    default:
      LOG(ERROR) << "Codec " << codec() << " is not supported in TS yet.";
      return false;
  }
  WritePrivateDataIndicatorDescriptor(fourcc, descriptors);
  return true;
}
 
AudioProgramMapTableWriter::AudioProgramMapTableWriter(
    Codec codec,
    const std::vector<uint8_t>& audio_specific_config)
    : ProgramMapTableWriter(codec),
      audio_specific_config_(audio_specific_config) {
  DCHECK(!audio_specific_config.empty());
}
 
bool AudioProgramMapTableWriter::WriteDescriptors(
    BufferWriter* descriptors) const {
  FourCC fourcc;
  switch (codec()) {
    case kCodecAAC:
      fourcc = FOURCC_aacd;
      break;
    case kCodecMP3:
      fourcc = FOURCC_mp3a;
      break;
    case kCodecAC3:
      fourcc = FOURCC_ac3d;
      break;
    case kCodecEAC3:
      fourcc = FOURCC_ec3d;
      break;
    default:
      LOG(ERROR) << "Codec " << codec() << " is not supported in TS yet.";
      return false;
  }
  WritePrivateDataIndicatorDescriptor(fourcc, descriptors);
 
  // NOTE: There are two specifications of carrying AC-3 bit stream in MPEG-2
  // transport stream (ISO/IEC 13818-1):
  //   System A used by ATSC (TS 102 366 Digital Audio Compression Standard)
  //     stream_type: 0x81
  //     system_id:   0xBD (private_stream_1)
  //     Requires Registration_descriptor, AC-3_audio_stream_descriptor.
  //     Optional ISO_639_language_code descriptor.
  //   System B used by DVB (TS 101 154 DVB specification for ... based on the
  //                         MPEG-2 Transport Stream)
  //     stream_type: 0x06 (private data)
  //     stream_id:   0xBD (private_stream_1)
  //     Requires AC-3_descriptor (not the same as AC-3_audio_stream_descriptor
  //     in ATSC)
  //     Optional ISO_639_language_code descriptor.
  // We follow "System A" but not strictly as we do not include Registration
  // descriptor and AC-3_audio_stream_descriptor right now.
 
  return WriteRegistrationDescriptorForEncryptedAudio(
      codec(), audio_specific_config_.data(), audio_specific_config_.size(),
      descriptors);
}
 
}  // namespace mp2t
}  // namespace media
}  // namespace shaka