# All files / src/controller subtitle-stream-controller.js

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30.77% Branches 24/78
73.68% Functions 14/19
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     /**
     * @class SubtitleStreamController
     */

    import Event from '../events';
    import { logger } from '../utils/logger';
    import Decrypter from '../crypt/decrypter';
    import { BufferHelper } from '../utils/buffer-helper';
    import { findFragmentByPDT, findFragmentByPTS } from './fragment-finders';
    import { FragmentState } from './fragment-tracker';
    import BaseStreamController, { State } from './base-stream-controller';
    import { mergeSubtitlePlaylists } from './level-helper';

    const { performance } = window;
    const TICK_INTERVAL = 500; // how often to tick in ms

    export class SubtitleStreamController extends BaseStreamController {
      constructor (hls, fragmentTracker) {
        super(hls,
          Event.MEDIA_ATTACHED,
          Event.MEDIA_DETACHING,
          Event.ERROR,
          Event.KEY_LOADED,
          Event.FRAG_LOADED,
          Event.SUBTITLE_TRACKS_UPDATED,
          Event.SUBTITLE_TRACK_SWITCH,
          Event.SUBTITLE_TRACK_LOADED,
          Event.SUBTITLE_FRAG_PROCESSED,
          Event.LEVEL_UPDATED);

        this.fragmentTracker = fragmentTracker;
        this.config = hls.config;
        this.state = State.STOPPED;
        this.tracks = [];
        this.tracksBuffered = [];
        this.currentTrackId = -1;
        this.decrypter = new Decrypter(hls, hls.config);
        // lastAVStart stores the time in seconds for the start time of a level load
        this.lastAVStart = 0;
        this._onMediaSeeking = this.onMediaSeeking.bind(this);
      }

      onSubtitleFragProcessed (data) {
        const { frag, success } = data;
        this.fragPrevious = frag;
        this.state = State.IDLE;
        if (!success) {
          return;
        }

        const buffered = this.tracksBuffered[this.currentTrackId];
        if (!buffered) {
          return;
        }

        // Create/update a buffered array matching the interface used by BufferHelper.bufferedInfo
        // so we can re-use the logic used to detect how much have been buffered
        let timeRange;
        const fragStart = frag.start;
        for (let i = 0; i < buffered.length; i++) {
          if (fragStart >= buffered[i].start && fragStart <= buffered[i].end) {
            timeRange = buffered[i];
            break;
          }
        }

        const fragEnd = frag.start + frag.duration;
        if (timeRange) {
          timeRange.end = fragEnd;
        } else {
          timeRange = {
            start: fragStart,
            end: fragEnd
          };
          buffered.push(timeRange);
        }
      }

      onMediaAttached ({ media }) {
        this.media = media;
        media.addEventListener('seeking', this._onMediaSeeking);
        this.state = State.IDLE;
      }

      onMediaDetaching () {
        if (!this.media) {
          return;
        }
        this.media.removeEventListener('seeking', this._onMediaSeeking);
        this.fragmentTracker.removeAllFragments();
        this.currentTrackId = -1;
        this.tracks.forEach((track) => {
          this.tracksBuffered[track.id] = [];
        });
        this.media = null;
        this.state = State.STOPPED;
      }

      // If something goes wrong, proceed to next frag, if we were processing one.
      onError (data) {
        let frag = data.frag;
        // don't handle error not related to subtitle fragment
        Eif (!frag || frag.type !== 'subtitle') {
          return;
        }
        this.state = State.IDLE;
      }

      // Got all new subtitle tracks.
      onSubtitleTracksUpdated (data) {
        logger.log('subtitle tracks updated');
        this.tracksBuffered = [];
        this.tracks = data.subtitleTracks;
        this.tracks.forEach((track) => {
          this.tracksBuffered[track.id] = [];
        });
      }

      onSubtitleTrackSwitch (data) {
        this.currentTrackId = data.id;

        if (!this.tracks || !this.tracks.length || this.currentTrackId === -1) {
          this.clearInterval();
          return;
        }

        // Check if track has the necessary details to load fragments
        const currentTrack = this.tracks[this.currentTrackId];
        Eif (currentTrack && currentTrack.details) {
          this.setInterval(TICK_INTERVAL);
        }
      }

      // Got a new set of subtitle fragments.
      onSubtitleTrackLoaded (data) {
        const { id, details } = data;
        const { currentTrackId, tracks } = this;
        const currentTrack = tracks[currentTrackId];
        if (id >= tracks.length || id !== currentTrackId || !currentTrack) {
          return;
        }

        Iif (details.live) {
          mergeSubtitlePlaylists(currentTrack.details, details, this.lastAVStart);
        }
        currentTrack.details = details;
        this.setInterval(TICK_INTERVAL);
      }

      onKeyLoaded () {
        if (this.state === State.KEY_LOADING) {
          this.state = State.IDLE;
        }
      }

      onFragLoaded (data) {
        const fragCurrent = this.fragCurrent;
        const decryptData = data.frag.decryptdata;
        const fragLoaded = data.frag;
        const hls = this.hls;

        Iif (this.state === State.FRAG_LOADING &&
            fragCurrent &&
            data.frag.type === 'subtitle' &&
            fragCurrent.sn === data.frag.sn) {
          // check to see if the payload needs to be decrypted
          if (data.payload.byteLength > 0 && (decryptData && decryptData.key && decryptData.method === 'AES-128')) {
            let startTime = performance.now();

            // decrypt the subtitles
            this.decrypter.decrypt(data.payload, decryptData.key.buffer, decryptData.iv.buffer, function (decryptedData) {
              let endTime = performance.now();
              hls.trigger(Event.FRAG_DECRYPTED, { frag: fragLoaded, payload: decryptedData, stats: { tstart: startTime, tdecrypt: endTime } });
            });
          }
        }
      }

      onLevelUpdated ({ details }) {
        const frags = details.fragments;
        this.lastAVStart = frags.length ? frags[0].start : 0;
      }

      doTick () {
        if (!this.media) {
          this.state = State.IDLE;
          return;
        }

        switch (this.state) {
        case State.IDLE: {
          const { config, currentTrackId, fragmentTracker, media, tracks } = this;
          if (!tracks || !tracks[currentTrackId] || !tracks[currentTrackId].details) {
            break;
          }

          const { maxBufferHole, maxFragLookUpTolerance } = config;
          const maxConfigBuffer = Math.min(config.maxBufferLength, config.maxMaxBufferLength);
          const bufferedInfo = BufferHelper.bufferedInfo(this._getBuffered(), media.currentTime, maxBufferHole);
          const { end: bufferEnd, len: bufferLen } = bufferedInfo;

          const trackDetails = tracks[currentTrackId].details;
          const fragments = trackDetails.fragments;
          const fragLen = fragments.length;
          const end = fragments[fragLen - 1].start + fragments[fragLen - 1].duration;

          if (bufferLen > maxConfigBuffer) {
            return;
          }

          let foundFrag;
          const fragPrevious = this.fragPrevious;
          if (bufferEnd < end) {
            if (fragPrevious && trackDetails.hasProgramDateTime) {
              foundFrag = findFragmentByPDT(fragments, fragPrevious.endProgramDateTime, maxFragLookUpTolerance);
            }
            if (!foundFrag) {
              foundFrag = findFragmentByPTS(fragPrevious, fragments, bufferEnd, maxFragLookUpTolerance);
            }
          } else {
            foundFrag = fragments[fragLen - 1];
          }

          if (foundFrag && foundFrag.encrypted) {
            logger.log(`Loading key for ${foundFrag.sn}`);
            this.state = State.KEY_LOADING;
            this.hls.trigger(Event.KEY_LOADING, { frag: foundFrag });
          } else if (foundFrag && fragmentTracker.getState(foundFrag) === FragmentState.NOT_LOADED) {
            // only load if fragment is not loaded
            this.fragCurrent = foundFrag;
            this.state = State.FRAG_LOADING;
            this.hls.trigger(Event.FRAG_LOADING, { frag: foundFrag });
          }
        }
        }
      }

      stopLoad () {
        this.lastAVStart = 0;
        super.stopLoad();
      }

      _getBuffered () {
        return this.tracksBuffered[this.currentTrackId] || [];
      }

      onMediaSeeking () {
        this.fragPrevious = null;
      }
    }