h264_byte_to_unit_stream_converter.cc

// Copyright 2014 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/codecs/h264_byte_to_unit_stream_converter.h>
 
#include <limits>
 
#include <absl/log/check.h>
#include <absl/log/log.h>
 
#include <packager/media/base/buffer_writer.h>
#include <packager/media/codecs/h264_parser.h>
 
namespace shaka {
namespace media {
 
namespace {
// utility helper function to get an sps
const H264Sps* ParseSpsFromBytes(const std::vector<uint8_t> sps,
                                 H264Parser* parser) {
  Nalu nalu;
  if (!nalu.Initialize(Nalu::kH264, sps.data(), sps.size()))
    return nullptr;
 
  int sps_id = 0;
  if (parser->ParseSps(nalu, &sps_id) != H264Parser::kOk)
    return nullptr;
  return parser->GetSps(sps_id);
}
} // namespace
 
H264ByteToUnitStreamConverter::H264ByteToUnitStreamConverter()
    : H26xByteToUnitStreamConverter(Nalu::kH264) {}
 
H264ByteToUnitStreamConverter::H264ByteToUnitStreamConverter(
    H26xStreamFormat stream_format)
    : H26xByteToUnitStreamConverter(Nalu::kH264, stream_format) {}
 
H264ByteToUnitStreamConverter::~H264ByteToUnitStreamConverter() {}
 
bool H264ByteToUnitStreamConverter::GetDecoderConfigurationRecord(
    std::vector<uint8_t>* decoder_config) const {
  DCHECK(decoder_config);
  if ((last_sps_.size() < 4) || last_pps_.empty()) {
    // No data available to construct AVCDecoderConfigurationRecord.
    return false;
  }
  // Construct an AVCDecoderConfigurationRecord containing a single SPS, a
  // single PPS, and if available, a single SPS Extension NALU. 
  // Please refer to ISO/IEC 14496-15 for format specifics.
  BufferWriter buffer;
  uint8_t version(1);
  buffer.AppendInt(version);
  buffer.AppendInt(last_sps_[1]);
  buffer.AppendInt(last_sps_[2]);
  buffer.AppendInt(last_sps_[3]);
  uint8_t reserved_and_length_size_minus_one(0xff);
  buffer.AppendInt(reserved_and_length_size_minus_one);
  uint8_t reserved_and_num_sps(0xe1);
  buffer.AppendInt(reserved_and_num_sps);
  buffer.AppendInt(static_cast<uint16_t>(last_sps_.size()));
  buffer.AppendVector(last_sps_);
  uint8_t num_pps(1);
  buffer.AppendInt(num_pps);
  buffer.AppendInt(static_cast<uint16_t>(last_pps_.size()));
  buffer.AppendVector(last_pps_);
  // handle profile special cases, refer to ISO/IEC 14496-15 Section 5.3.3.1.2
  uint8_t profile_indication = last_sps_[1];
  if (profile_indication == 100 || profile_indication == 110 || 
      profile_indication == 122 || profile_indication == 144) {
      
      H264Parser parser;
      const H264Sps* sps = ParseSpsFromBytes(last_sps_, &parser);
      if (sps == nullptr)
        return false;
 
      uint8_t reserved_chroma_format = 0xfc | (sps->chroma_format_idc);
      buffer.AppendInt(reserved_chroma_format);
      uint8_t reserved_bit_depth_luma_minus8 = 0xf8 | sps->bit_depth_luma_minus8;
      buffer.AppendInt(reserved_bit_depth_luma_minus8);
      uint8_t reserved_bit_depth_chroma_minus8 = 0xf8 | sps->bit_depth_chroma_minus8;
      buffer.AppendInt(reserved_bit_depth_chroma_minus8);   
      
      if (last_sps_ext_.empty()) {
        uint8_t num_sps_ext(0);
        buffer.AppendInt(num_sps_ext);     
      } else {
        uint8_t num_sps_ext(1);
        buffer.AppendInt(num_sps_ext);     
        buffer.AppendVector(last_sps_ext_);
      }
  }
 
  buffer.SwapBuffer(decoder_config);
  return true;
}
 
bool H264ByteToUnitStreamConverter::ProcessNalu(const Nalu& nalu) {
  DCHECK(nalu.data());
 
  // Skip the start code, but keep the 1-byte NALU type.
  const uint8_t* nalu_ptr = nalu.data();
  const uint64_t nalu_size = nalu.payload_size() + nalu.header_size();
 
  switch (nalu.type()) {
    case Nalu::H264_SPS:
      if (strip_parameter_set_nalus())
        WarnIfNotMatch(nalu.type(), nalu_ptr, nalu_size, last_sps_);
      // Grab SPS NALU.
      last_sps_.assign(nalu_ptr, nalu_ptr + nalu_size);
      return strip_parameter_set_nalus();
    case Nalu::H264_SPSExtension:
      if (strip_parameter_set_nalus())
        WarnIfNotMatch(nalu.type(), nalu_ptr, nalu_size, last_sps_ext_);
      // Grab SPSExtension NALU.
      last_sps_ext_.assign(nalu_ptr, nalu_ptr + nalu_size);
      return strip_parameter_set_nalus();
    case Nalu::H264_PPS:
      if (strip_parameter_set_nalus())
        WarnIfNotMatch(nalu.type(), nalu_ptr, nalu_size, last_pps_);
      // Grab PPS NALU.
      last_pps_.assign(nalu_ptr, nalu_ptr + nalu_size);
      return strip_parameter_set_nalus();
    case Nalu::H264_AUD:
      // Ignore AUD NALU.
      return true;
    default:
      // Have the base class handle other NALU types.
      return false;
  }
}
 
}  // namespace media
}  // namespace shaka