mp4box/src/parsing/vvcC.js

JavaScript version of GPAC's MP4Box tool

BoxParser.createFullBoxCtor("vvcC", "VvcConfigurationBox", function (stream) {
  var i, j;

  // helper object to simplify extracting individual bits
  var bitReader = {
    held_bits: undefined,
    num_held_bits: 0,

    stream_read_1_bytes: function (strm) {
      this.held_bits = strm.readUint8();
      this.num_held_bits = 1 * 8;
    },
    stream_read_2_bytes: function (strm) {
      this.held_bits = strm.readUint16();
      this.num_held_bits = 2 * 8;
    },

    extract_bits: function (num_bits) {
      var ret = (this.held_bits >> (this.num_held_bits - num_bits)) & ((1 << num_bits) - 1);
      this.num_held_bits -= num_bits;
      return ret;
    }
  };

  // VvcDecoderConfigurationRecord
  bitReader.stream_read_1_bytes(stream);
  bitReader.extract_bits(5);  // reserved
  this.lengthSizeMinusOne = bitReader.extract_bits(2);
  this.ptl_present_flag = bitReader.extract_bits(1);

  if (this.ptl_present_flag) {
    bitReader.stream_read_2_bytes(stream);
    this.ols_idx = bitReader.extract_bits(9);
    this.num_sublayers = bitReader.extract_bits(3);
    this.constant_frame_rate = bitReader.extract_bits(2);
    this.chroma_format_idc = bitReader.extract_bits(2);

    bitReader.stream_read_1_bytes(stream);
    this.bit_depth_minus8 = bitReader.extract_bits(3);
    bitReader.extract_bits(5);  // reserved

    // VvcPTLRecord
    {
      bitReader.stream_read_2_bytes(stream);
      bitReader.extract_bits(2);  // reserved
      this.num_bytes_constraint_info = bitReader.extract_bits(6);
      this.general_profile_idc = bitReader.extract_bits(7);
      this.general_tier_flag = bitReader.extract_bits(1);

      this.general_level_idc = stream.readUint8();

      bitReader.stream_read_1_bytes(stream);
      this.ptl_frame_only_constraint_flag = bitReader.extract_bits(1);
      this.ptl_multilayer_enabled_flag = bitReader.extract_bits(1);

      this.general_constraint_info = new Uint8Array(this.num_bytes_constraint_info);
      if (this.num_bytes_constraint_info) {
        for (i = 0; i < this.num_bytes_constraint_info - 1; i++) {
          var cnstr1 = bitReader.extract_bits(6);
          bitReader.stream_read_1_bytes(stream);
          var cnstr2 = bitReader.extract_bits(2);

          this.general_constraint_info[i] = ((cnstr1 << 2) | cnstr2);
        }
        this.general_constraint_info[this.num_bytes_constraint_info - 1] = bitReader.extract_bits(6);
      } else {
        //forbidden in spec!
        bitReader.extract_bits(6);
      }

      if (this.num_sublayers > 1) {
        bitReader.stream_read_1_bytes(stream);
        this.ptl_sublayer_present_mask = 0;
        for (j = this.num_sublayers - 2; j >= 0; --j) {
          var val = bitReader.extract_bits(1);
          this.ptl_sublayer_present_mask |= val << j;
        }
        for (j = this.num_sublayers; j <= 8 && this.num_sublayers > 1; ++j) {
          bitReader.extract_bits(1);  // ptl_reserved_zero_bit
        }

        this.sublayer_level_idc = [];
        for (j = this.num_sublayers - 2; j >= 0; --j) {
          if (this.ptl_sublayer_present_mask & (1 << j)) {
            this.sublayer_level_idc[j] = stream.readUint8();
          }
        }
      }

      this.ptl_num_sub_profiles = stream.readUint8();
      this.general_sub_profile_idc = [];
      if (this.ptl_num_sub_profiles) {
        for (i = 0; i < this.ptl_num_sub_profiles; i++) {
          this.general_sub_profile_idc.push(stream.readUint32());
        }
      }
    }  // end VvcPTLRecord

    this.max_picture_width = stream.readUint16();
    this.max_picture_height = stream.readUint16();
    this.avg_frame_rate = stream.readUint16();
  }

  var VVC_NALU_OPI = 12;
  var VVC_NALU_DEC_PARAM = 13;

  this.nalu_arrays = [];
  var num_of_arrays = stream.readUint8();
  for (i = 0; i < num_of_arrays; i++) {
    var nalu_array = [];
    this.nalu_arrays.push(nalu_array);

    bitReader.stream_read_1_bytes(stream);
    nalu_array.completeness = bitReader.extract_bits(1);
    bitReader.extract_bits(2);  // reserved
    nalu_array.nalu_type = bitReader.extract_bits(5);

    var numNalus = 1;
    if (nalu_array.nalu_type != VVC_NALU_DEC_PARAM && nalu_array.nalu_type != VVC_NALU_OPI) {
      numNalus = stream.readUint16();
    }

    for (j = 0; j < numNalus; j++) {
      var len = stream.readUint16();
      nalu_array.push({
        data: stream.readUint8Array(len),
        length: len
      });
    }
  }
});