static getCapabilities_(manifestDb, isVideo) {
    const MimeUtils = shaka.util.MimeUtils;

    const ret = [];
    for (const stream of manifestDb.streams) {
      if (isVideo && stream.type == 'video') {
        ret.push({
          contentType: MimeUtils.getFullType(stream.mimeType, stream.codecs),
          robustness: manifestDb.drmInfo.videoRobustness,
        });
      } else if (!isVideo && stream.type == 'audio') {
        ret.push({
          contentType: MimeUtils.getFullType(stream.mimeType, stream.codecs),
          robustness: manifestDb.drmInfo.audioRobustness,
        });
      }
    }
    return ret;
  }
@param {shaka.extern.ManifestDB} manifestDb
@param {boolean} isVideo
@return {!Array<MediaKeySystemMediaCapability>}
@private