static parseAV1C(codecBase, reader, boxName) {
    const Mp4BoxParsers = shaka.util.Mp4BoxParsers;
    // More info https://aomediacodec.github.io/av1-isobmff/#av1codecconfigurationbox-syntax
    reader.skip(1); // Skip "marker" and "version"
    const secondByte = reader.readUint8();
    const thirdByte = reader.readUint8();
    const profile = secondByte >>> 5;
    const level = secondByte & 0x1f;
    const tierFlag = thirdByte >>> 7 ? 'H' : 'M';
    const highBitDepth = (thirdByte & 0x40) >> 6;
    const twelveBit = (thirdByte & 0x20) >> 5;
    const bitDepth = profile === 2 && highBitDepth ?
        (twelveBit ? 12 : 10) : (highBitDepth ? 10 : 8);
    const monochrome = (thirdByte & 0x10) >> 4;
    const chromaSubsamplingX = (thirdByte & 0x08) >> 3;
    const chromaSubsamplingY = (thirdByte & 0x04) >> 2;
    const chromaSamplePosition = thirdByte & 0x03;
    // TODO: parse color_description_present_flag
    // default it to BT.709/limited range for now
    const colorPrimaries = 1;
    const transferCharacteristics = 1;
    const matrixCoefficients = 1;
    const videoFullRangeFlag = 0;
    const codec = codecBase + '.' + profile +
      '.' + Mp4BoxParsers.addLeadingZero_(level) + tierFlag +
      '.' + Mp4BoxParsers.addLeadingZero_(bitDepth) +
      '.' + monochrome +
      '.' + chromaSubsamplingX + chromaSubsamplingY + chromaSamplePosition +
      '.' + Mp4BoxParsers.addLeadingZero_(colorPrimaries) +
      '.' + Mp4BoxParsers.addLeadingZero_(transferCharacteristics) +
      '.' + Mp4BoxParsers.addLeadingZero_(matrixCoefficients) +
      '.' + videoFullRangeFlag;

    return {codec};
  }
Parses a AV1C box.
@param {string} codecBase
@param {!shaka.util.DataViewReader} reader
@param {string} boxName
@return {!shaka.util.ParsedAV1CBox}