# All files / src/controller buffer-controller.js

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     /*
     * Buffer Controller
    */

    import Event from '../events';
    import EventHandler from '../event-handler';
    import { logger } from '../utils/logger';
    import { ErrorTypes, ErrorDetails } from '../errors';
    import { getMediaSource } from '../utils/mediasource-helper';

    const MediaSource = getMediaSource();

    class BufferController extends EventHandler {
      constructor (hls) {
        super(hls,
          Event.MEDIA_ATTACHING,
          Event.MEDIA_DETACHING,
          Event.MANIFEST_PARSED,
          Event.BUFFER_RESET,
          Event.BUFFER_APPENDING,
          Event.BUFFER_CODECS,
          Event.BUFFER_EOS,
          Event.BUFFER_FLUSHING,
          Event.LEVEL_PTS_UPDATED,
          Event.LEVEL_UPDATED);

        // the value that we have set mediasource.duration to
        // (the actual duration may be tweaked slighly by the browser)
        this._msDuration = null;
        // the value that we want to set mediaSource.duration to
        this._levelDuration = null;
        // current stream state: true - for live broadcast, false - for VoD content
        this._live = null;
        // cache the self generated object url to detect hijack of video tag
        this._objectUrl = null;

        // Source Buffer listeners
        this.onsbue = this.onSBUpdateEnd.bind(this);
        this.onsbe = this.onSBUpdateError.bind(this);
        this.pendingTracks = {};
        this.tracks = {};
      }

      destroy () {
        EventHandler.prototype.destroy.call(this);
      }

      onLevelPtsUpdated (data) {
        let type = data.type;
        let audioTrack = this.tracks.audio;

        // Adjusting `SourceBuffer.timestampOffset` (desired point in the timeline where the next frames should be appended)
        // in Chrome browser when we detect MPEG audio container and time delta between level PTS and `SourceBuffer.timestampOffset`
        // is greater than 100ms (this is enough to handle seek for VOD or level change for LIVE videos). At the time of change we issue
        // `SourceBuffer.abort()` and adjusting `SourceBuffer.timestampOffset` if `SourceBuffer.updating` is false or awaiting `updateend`
        // event if SB is in updating state.
        // More info here: https://github.com/video-dev/hls.js/issues/332#issuecomment-257986486

        if (type === 'audio' && audioTrack && audioTrack.container === 'audio/mpeg') { // Chrome audio mp3 track
          let audioBuffer = this.sourceBuffer.audio;
          let delta = Math.abs(audioBuffer.timestampOffset - data.start);

          // adjust timestamp offset if time delta is greater than 100ms
          if (delta > 0.1) {
            let updating = audioBuffer.updating;

            try {
              audioBuffer.abort();
            } catch (err) {
              updating = true;
              logger.warn('can not abort audio buffer: ' + err);
            }

            if (!updating) {
              logger.warn('change mpeg audio timestamp offset from ' + audioBuffer.timestampOffset + ' to ' + data.start);
              audioBuffer.timestampOffset = data.start;
            } else {
              this.audioTimestampOffset = data.start;
            }
          }
        }
      }

      onManifestParsed (data) {
        let audioExpected = data.audio,
          videoExpected = data.video || (data.levels.length && data.altAudio),
          sourceBufferNb = 0;
        // in case of alt audio 2 BUFFER_CODECS events will be triggered, one per stream controller
        // sourcebuffers will be created all at once when the expected nb of tracks will be reached
        // in case alt audio is not used, only one BUFFER_CODEC event will be fired from main stream controller
        // it will contain the expected nb of source buffers, no need to compute it
        if (data.altAudio && (audioExpected || videoExpected)) {
          sourceBufferNb = (audioExpected ? 1 : 0) + (videoExpected ? 1 : 0);
          logger.log(`${sourceBufferNb} sourceBuffer(s) expected`);
        }
        this.sourceBufferNb = sourceBufferNb;
      }

      onMediaAttaching (data) {
        let media = this.media = data.media;
        if (media) {
          // setup the media source
          let ms = this.mediaSource = new MediaSource();
          // Media Source listeners
          this.onmso = this.onMediaSourceOpen.bind(this);
          this.onmse = this.onMediaSourceEnded.bind(this);
          this.onmsc = this.onMediaSourceClose.bind(this);
          ms.addEventListener('sourceopen', this.onmso);
          ms.addEventListener('sourceended', this.onmse);
          ms.addEventListener('sourceclose', this.onmsc);
          // link video and media Source
          media.src = window.URL.createObjectURL(ms);
          // cache the locally generated object url
          this._objectUrl = media.src;
        }
      }

      onMediaDetaching () {
        logger.log('media source detaching');
        let ms = this.mediaSource;
        if (ms) {
          if (ms.readyState === 'open') {
            try {
              // endOfStream could trigger exception if any sourcebuffer is in updating state
              // we don't really care about checking sourcebuffer state here,
              // as we are anyway detaching the MediaSource
              // let's just avoid this exception to propagate
              ms.endOfStream();
            } catch (err) {
              logger.warn(`onMediaDetaching:${err.message} while calling endOfStream`);
            }
          }
          ms.removeEventListener('sourceopen', this.onmso);
          ms.removeEventListener('sourceended', this.onmse);
          ms.removeEventListener('sourceclose', this.onmsc);

          // Detach properly the MediaSource from the HTMLMediaElement as
          // suggested in https://github.com/w3c/media-source/issues/53.
          if (this.media) {
            window.URL.revokeObjectURL(this._objectUrl);

            // clean up video tag src only if it's our own url. some external libraries might
            // hijack the video tag and change its 'src' without destroying the Hls instance first
            if (this.media.src === this._objectUrl) {
              this.media.removeAttribute('src');
              this.media.load();
            } else {
              logger.warn('media.src was changed by a third party - skip cleanup');
            }
          }

          this.mediaSource = null;
          this.media = null;
          this._objectUrl = null;
          this.pendingTracks = {};
          this.tracks = {};
          this.sourceBuffer = {};
          this.flushRange = [];
          this.segments = [];
          this.appended = 0;
        }
        this.onmso = this.onmse = this.onmsc = null;
        this.hls.trigger(Event.MEDIA_DETACHED);
      }

      onMediaSourceOpen () {
        logger.log('media source opened');
        this.hls.trigger(Event.MEDIA_ATTACHED, { media: this.media });
        let mediaSource = this.mediaSource;
        if (mediaSource) {
          // once received, don't listen anymore to sourceopen event
          mediaSource.removeEventListener('sourceopen', this.onmso);
        }
        this.checkPendingTracks();
      }

      checkPendingTracks () {
        // if any buffer codecs pending, check if we have enough to create sourceBuffers
        let pendingTracks = this.pendingTracks,
          pendingTracksNb = Object.keys(pendingTracks).length;
        // if any pending tracks and (if nb of pending tracks gt or equal than expected nb or if unknown expected nb)
        if (pendingTracksNb && (
          this.sourceBufferNb <= pendingTracksNb ||
            this.sourceBufferNb === 0)) {
          // ok, let's create them now !
          this.createSourceBuffers(pendingTracks);
          this.pendingTracks = {};
          // append any pending segments now !
          this.doAppending();
        }
      }

      onMediaSourceClose () {
        logger.log('media source closed');
      }

      onMediaSourceEnded () {
        logger.log('media source ended');
      }

      onSBUpdateEnd () {
        // update timestampOffset
        if (this.audioTimestampOffset) {
          let audioBuffer = this.sourceBuffer.audio;
          logger.warn('change mpeg audio timestamp offset from ' + audioBuffer.timestampOffset + ' to ' + this.audioTimestampOffset);
          audioBuffer.timestampOffset = this.audioTimestampOffset;
          delete this.audioTimestampOffset;
        }

        if (this._needsFlush) {
          this.doFlush();
        }

        if (this._needsEos) {
          this.checkEos();
        }

        this.appending = false;
        let parent = this.parent;
        // count nb of pending segments waiting for appending on this sourcebuffer
        let pending = this.segments.reduce((counter, segment) => (segment.parent === parent) ? counter + 1 : counter, 0);

        // this.sourceBuffer is better to use than media.buffered as it is closer to the PTS data from the fragments
        let timeRanges = {};
        const sourceBuffer = this.sourceBuffer;
        for (let streamType in sourceBuffer) {
          timeRanges[streamType] = sourceBuffer[streamType].buffered;
        }

        this.hls.trigger(Event.BUFFER_APPENDED, { parent, pending, timeRanges });
        // don't append in flushing mode
        if (!this._needsFlush) {
          this.doAppending();
        }

        this.updateMediaElementDuration();
      }

      onSBUpdateError (event) {
        logger.error('sourceBuffer error:', event);
        // according to http://www.w3.org/TR/media-source/#sourcebuffer-append-error
        // this error might not always be fatal (it is fatal if decode error is set, in that case
        // it will be followed by a mediaElement error ...)
        this.hls.trigger(Event.ERROR, { type: ErrorTypes.MEDIA_ERROR, details: ErrorDetails.BUFFER_APPENDING_ERROR, fatal: false });
        // we don't need to do more than that, as accordin to the spec, updateend will be fired just after
      }

      onBufferReset () {
        let sourceBuffer = this.sourceBuffer;
        for (let type in sourceBuffer) {
          let sb = sourceBuffer[type];
          try {
            this.mediaSource.removeSourceBuffer(sb);
            sb.removeEventListener('updateend', this.onsbue);
            sb.removeEventListener('error', this.onsbe);
          } catch (err) {
          }
        }
        this.sourceBuffer = {};
        this.flushRange = [];
        this.segments = [];
        this.appended = 0;
      }

      onBufferCodecs (tracks) {
        // if source buffer(s) not created yet, appended buffer tracks in this.pendingTracks
        // if sourcebuffers already created, do nothing ...
        if (Object.keys(this.sourceBuffer).length === 0) {
          for (let trackName in tracks) this.pendingTracks[trackName] = tracks[trackName];
          let mediaSource = this.mediaSource;
          if (mediaSource && mediaSource.readyState === 'open') {
            // try to create sourcebuffers if mediasource opened
            this.checkPendingTracks();
          }
        }
      }

      createSourceBuffers (tracks) {
        let sourceBuffer = this.sourceBuffer, mediaSource = this.mediaSource;

        for (let trackName in tracks) {
          if (!sourceBuffer[trackName]) {
            let track = tracks[trackName];
            // use levelCodec as first priority
            let codec = track.levelCodec || track.codec;
            let mimeType = `${track.container};codecs=${codec}`;
            logger.log(`creating sourceBuffer(${mimeType})`);
            try {
              let sb = sourceBuffer[trackName] = mediaSource.addSourceBuffer(mimeType);
              sb.addEventListener('updateend', this.onsbue);
              sb.addEventListener('error', this.onsbe);
              this.tracks[trackName] = { codec: codec, container: track.container };
              track.buffer = sb;
            } catch (err) {
              logger.error(`error while trying to add sourceBuffer:${err.message}`);
              this.hls.trigger(Event.ERROR, { type: ErrorTypes.MEDIA_ERROR, details: ErrorDetails.BUFFER_ADD_CODEC_ERROR, fatal: false, err: err, mimeType: mimeType });
            }
          }
        }
        this.hls.trigger(Event.BUFFER_CREATED, { tracks: tracks });
      }

      onBufferAppending (data) {
        if (!this._needsFlush) {
          if (!this.segments) {
            this.segments = [ data ];
          } else {
            this.segments.push(data);
          }

          this.doAppending();
        }
      }

      onBufferAppendFail (data) {
        logger.error('sourceBuffer error:', data.event);
        // according to http://www.w3.org/TR/media-source/#sourcebuffer-append-error
        // this error might not always be fatal (it is fatal if decode error is set, in that case
        // it will be followed by a mediaElement error ...)
        this.hls.trigger(Event.ERROR, { type: ErrorTypes.MEDIA_ERROR, details: ErrorDetails.BUFFER_APPENDING_ERROR, fatal: false });
      }

      // on BUFFER_EOS mark matching sourcebuffer(s) as ended and trigger checkEos()
      onBufferEos (data) {
        let sb = this.sourceBuffer;
        let dataType = data.type;
        for (let type in sb) {
          if (!dataType || type === dataType) {
            if (!sb[type].ended) {
              sb[type].ended = true;
              logger.log(`${type} sourceBuffer now EOS`);
            }
          }
        }
        this.checkEos();
      }

      // if all source buffers are marked as ended, signal endOfStream() to MediaSource.
      checkEos () {
        let sb = this.sourceBuffer, mediaSource = this.mediaSource;
        if (!mediaSource || mediaSource.readyState !== 'open') {
          this._needsEos = false;
          return;
        }
        for (let type in sb) {
          let sbobj = sb[type];
          if (!sbobj.ended) {
            return;
          }

          if (sbobj.updating) {
            this._needsEos = true;
            return;
          }
        }
        logger.log('all media data available, signal endOfStream() to MediaSource and stop loading fragment');
        // Notify the media element that it now has all of the media data
        try {
          mediaSource.endOfStream();
        } catch (e) {
          logger.warn('exception while calling mediaSource.endOfStream()');
        }
        this._needsEos = false;
      }

      onBufferFlushing (data) {
        this.flushRange.push({ start: data.startOffset, end: data.endOffset, type: data.type });
        // attempt flush immediately
        this.flushBufferCounter = 0;
        this.doFlush();
      }

      onLevelUpdated ({ details }) {
        if (details.fragments.length > 0) {
          this._levelDuration = details.totalduration + details.fragments[0].start;
          this._live = details.live;
          this.updateMediaElementDuration();
        }
      }

      /**
       * Update Media Source duration to current level duration or override to Infinity if configuration parameter
       * 'liveDurationInfinity` is set to `true`
       * More details: https://github.com/video-dev/hls.js/issues/355
       */
      updateMediaElementDuration () {
        let { config } = this.hls;
        let duration;

        if (this._levelDuration === null ||
          !this.media ||
          !this.mediaSource ||
          !this.sourceBuffer ||
          this.media.readyState === 0 ||
          this.mediaSource.readyState !== 'open') {
          return;
        }

        for (let type in this.sourceBuffer) {
          if (this.sourceBuffer[type].updating === true) {
            // can't set duration whilst a buffer is updating
            return;
          }
        }

        duration = this.media.duration;
        // initialise to the value that the media source is reporting
        if (this._msDuration === null) {
          this._msDuration = this.mediaSource.duration;
        }

        if (this._live === true && config.liveDurationInfinity === true) {
          // Override duration to Infinity
          logger.log('Media Source duration is set to Infinity');
          this._msDuration = this.mediaSource.duration = Infinity;
        } else if ((this._levelDuration > this._msDuration && this._levelDuration > duration) ||
          (duration === Infinity || isNaN(duration))) {
          // levelDuration was the last value we set.
          // not using mediaSource.duration as the browser may tweak this value
          // only update Media Source duration if its value increase, this is to avoid
          // flushing already buffered portion when switching between quality level
          logger.log(`Updating Media Source duration to ${this._levelDuration.toFixed(3)}`);
          this._msDuration = this.mediaSource.duration = this._levelDuration;
        }
      }

      doFlush () {
        // loop through all buffer ranges to flush
        while (this.flushRange.length) {
          let range = this.flushRange[0];
          // flushBuffer will abort any buffer append in progress and flush Audio/Video Buffer
          if (this.flushBuffer(range.start, range.end, range.type)) {
            // range flushed, remove from flush array
            this.flushRange.shift();
            this.flushBufferCounter = 0;
          } else {
            this._needsFlush = true;
            // avoid looping, wait for SB update end to retrigger a flush
            return;
          }
        }
        if (this.flushRange.length === 0) {
          // everything flushed
          this._needsFlush = false;

          // let's recompute this.appended, which is used to avoid flush looping
          let appended = 0;
          let sourceBuffer = this.sourceBuffer;
          try {
            for (let type in sourceBuffer) {
              appended += sourceBuffer[type].buffered.length;
            }
          } catch (error) {
            // error could be thrown while accessing buffered, in case sourcebuffer has already been removed from MediaSource
            // this is harmess at this stage, catch this to avoid reporting an internal exception
            logger.error('error while accessing sourceBuffer.buffered');
          }
          this.appended = appended;
          this.hls.trigger(Event.BUFFER_FLUSHED);
        }
      }

      doAppending () {
        let hls = this.hls, sourceBuffer = this.sourceBuffer, segments = this.segments;
        if (Object.keys(sourceBuffer).length) {
          if (this.media.error) {
            this.segments = [];
            logger.error('trying to append although a media error occured, flush segment and abort');
            return;
          }
          if (this.appending) {
            // logger.log(`sb appending in progress`);
            return;
          }
          if (segments && segments.length) {
            let segment = segments.shift();
            try {
              let type = segment.type, sb = sourceBuffer[type];
              if (sb) {
                if (!sb.updating) {
                  // reset sourceBuffer ended flag before appending segment
                  sb.ended = false;
                  // logger.log(`appending ${segment.content} ${type} SB, size:${segment.data.length}, ${segment.parent}`);
                  this.parent = segment.parent;
                  sb.appendBuffer(segment.data);
                  this.appendError = 0;
                  this.appended++;
                  this.appending = true;
                } else {
                  segments.unshift(segment);
                }
              } else {
                // in case we don't have any source buffer matching with this segment type,
                // it means that Mediasource fails to create sourcebuffer
                // discard this segment, and trigger update end
                this.onSBUpdateEnd();
              }
            } catch (err) {
              // in case any error occured while appending, put back segment in segments table
              logger.error(`error while trying to append buffer:${err.message}`);
              segments.unshift(segment);
              let event = { type: ErrorTypes.MEDIA_ERROR, parent: segment.parent };
              if (err.code !== 22) {
                if (this.appendError) {
                  this.appendError++;
                } else {
                  this.appendError = 1;
                }

                event.details = ErrorDetails.BUFFER_APPEND_ERROR;
                /* with UHD content, we could get loop of quota exceeded error until
                  browser is able to evict some data from sourcebuffer. retrying help recovering this
                */
                if (this.appendError > hls.config.appendErrorMaxRetry) {
                  logger.log(`fail ${hls.config.appendErrorMaxRetry} times to append segment in sourceBuffer`);
                  segments = [];
                  event.fatal = true;
                  hls.trigger(Event.ERROR, event);
                } else {
                  event.fatal = false;
                  hls.trigger(Event.ERROR, event);
                }
              } else {
                // QuotaExceededError: http://www.w3.org/TR/html5/infrastructure.html#quotaexceedederror
                // let's stop appending any segments, and report BUFFER_FULL_ERROR error
                this.segments = [];
                event.details = ErrorDetails.BUFFER_FULL_ERROR;
                event.fatal = false;
                hls.trigger(Event.ERROR, event);
              }
            }
          }
        }
      }

      /*
        flush specified buffered range,
        return true once range has been flushed.
        as sourceBuffer.remove() is asynchronous, flushBuffer will be retriggered on sourceBuffer update end
      */
      flushBuffer (startOffset, endOffset, typeIn) {
        let sb, i, bufStart, bufEnd, flushStart, flushEnd, sourceBuffer = this.sourceBuffer;
        if (Object.keys(sourceBuffer).length) {
          logger.log(`flushBuffer,pos/start/end: ${this.media.currentTime.toFixed(3)}/${startOffset}/${endOffset}`);
          // safeguard to avoid infinite looping : don't try to flush more than the nb of appended segments
          if (this.flushBufferCounter < this.appended) {
            for (let type in sourceBuffer) {
              // check if sourcebuffer type is defined (typeIn): if yes, let's only flush this one
              // if no, let's flush all sourcebuffers
              if (typeIn && type !== typeIn) {
                continue;
              }

              sb = sourceBuffer[type];
              // we are going to flush buffer, mark source buffer as 'not ended'
              sb.ended = false;
              if (!sb.updating) {
                try {
                  for (i = 0; i < sb.buffered.length; i++) {
                    bufStart = sb.buffered.start(i);
                    bufEnd = sb.buffered.end(i);
                    // workaround firefox not able to properly flush multiple buffered range.
                    if (navigator.userAgent.toLowerCase().indexOf('firefox') !== -1 && endOffset === Number.POSITIVE_INFINITY) {
                      flushStart = startOffset;
                      flushEnd = endOffset;
                    } else {
                      flushStart = Math.max(bufStart, startOffset);
                      flushEnd = Math.min(bufEnd, endOffset);
                    }
                    /* sometimes sourcebuffer.remove() does not flush
                       the exact expected time range.
                       to avoid rounding issues/infinite loop,
                       only flush buffer range of length greater than 500ms.
                    */
                    if (Math.min(flushEnd, bufEnd) - flushStart > 0.5) {
                      this.flushBufferCounter++;
                      logger.log(`flush ${type} [${flushStart},${flushEnd}], of [${bufStart},${bufEnd}], pos:${this.media.currentTime}`);
                      sb.remove(flushStart, flushEnd);
                      return false;
                    }
                  }
                } catch (e) {
                  logger.warn('exception while accessing sourcebuffer, it might have been removed from MediaSource');
                }
              } else {
                // logger.log('abort ' + type + ' append in progress');
                // this will abort any appending in progress
                // sb.abort();
                logger.warn('cannot flush, sb updating in progress');
                return false;
              }
            }
          } else {
            logger.warn('abort flushing too many retries');
          }
          logger.log('buffer flushed');
        }
        // everything flushed !
        return true;
      }
    }

    export default BufferController;