function createStreamGenerator(metadata) {
      if (metadata.segmentUri.includes('.ts')) {
        return new shaka.test.TSVodStreamGenerator(
            metadata.segmentUri, metadata.segmentDuration);
      }
      if (metadata.segmentUri.includes('.aac')) {
        return new shaka.test.AACVodStreamGenerator(metadata.segmentUri);
      }
      return new shaka.test.Mp4VodStreamGenerator(
          metadata.initSegmentUri, metadata.mdhdOffset, metadata.segmentUri,
          metadata.tfdtOffset, metadata.segmentDuration);
    }
@param {AVMetadataType} metadata
@return {!shaka.test.IStreamGenerator}