parse method

dynamic parse(int indexEndoffset)

Implementation

parse(int indexEndoffset) {
  read(8, ignore: true); //  跳过8字节header
  final int versionAndFlags = read(4);
  final version = versionAndFlags >> 24; // version 只是高8位
  final flags = versionAndFlags & 0xFFFFFF;
  final referenceId = read(4);
  final timeScale = read(4);
  var earliest_presentation_time = 0;
  var first_offset = 0;
  if (version == 0) {
    earliest_presentation_time = read(4);
    first_offset = read(4);
  } else {
    earliest_presentation_time = read(8);
    first_offset = read(8);
  }
  first_offset += indexEndoffset + 1;
  read(2, ignore: true); // skip reserved
  final reference_count = read(2);
  var references = [];
  var time = earliest_presentation_time;
  var offset = first_offset;
  for (var i = 0; i < reference_count; i++) {
    const reference_type = 0;
    final reference_size = read(4);
    final subsegment_duration = read(4);
    // 下面是 starts_with_SAP, SAP_type, SAP_delta_time 没用到,这里忽略掉
    read(4, ignore: true);
    final startRange = offset;
    final endRange = offset + reference_size;
    references.add({
      "reference_type": reference_type,
      "reference_size": reference_size,
      "subsegment_duration": subsegment_duration,
      "durationSec": subsegment_duration / timeScale,
      "startTimeSec": time / timeScale,
      "startRange": startRange,
      "endRange": endRange,
    });
    offset += reference_size;
    time += subsegment_duration;
  }
  return {
    "version": version,
    "flag": flags,
    "referenceId": referenceId,
    "timeScale": timeScale,
    "earliest_presentation_time": earliest_presentation_time,
    "first_offset": first_offset,
    "reference_count": reference_count,
    "references": references,
  };
}