static areAVStreamsExactMatch_(a, b) {
    if (a.mimeType != b.mimeType) {
      return false;
    }
    return shaka.util.PeriodCombiner.getCodec_(a.codecs) ===
        shaka.util.PeriodCombiner.getCodec_(b.codecs);
  }
@param {T} a
@param {T} b
@return {boolean}

@template T
Accepts either a StreamDB or Stream type.

@private