videojs-contrib-hls/es5/sync-controller.js

/**
 * @file sync-controller.js
 */

'use strict';

Object.defineProperty(exports, '__esModule', {
  value: true
});

var _createClass = (function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ('value' in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; })();

var _get = function get(_x2, _x3, _x4) { var _again = true; _function: while (_again) { var object = _x2, property = _x3, receiver = _x4; _again = false; if (object === null) object = Function.prototype; var desc = Object.getOwnPropertyDescriptor(object, property); if (desc === undefined) { var parent = Object.getPrototypeOf(object); if (parent === null) { return undefined; } else { _x2 = parent; _x3 = property; _x4 = receiver; _again = true; desc = parent = undefined; continue _function; } } else if ('value' in desc) { return desc.value; } else { var getter = desc.get; if (getter === undefined) { return undefined; } return getter.call(receiver); } } };

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { 'default': obj }; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError('Cannot call a class as a function'); } }

function _inherits(subClass, superClass) { if (typeof superClass !== 'function' && superClass !== null) { throw new TypeError('Super expression must either be null or a function, not ' + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }

var _muxJsLibMp4Probe = require('mux.js/lib/mp4/probe');

var _muxJsLibMp4Probe2 = _interopRequireDefault(_muxJsLibMp4Probe);

var _muxJsLibToolsTsInspectorJs = require('mux.js/lib/tools/ts-inspector.js');

var _playlist = require('./playlist');

var _videoJs = require('video.js');

var _videoJs2 = _interopRequireDefault(_videoJs);

var syncPointStrategies = [
// Stategy "VOD": Handle the VOD-case where the sync-point is *always*
//                the equivalence display-time 0 === segment-index 0
{
  name: 'VOD',
  run: function run(syncController, playlist, duration, currentTimeline, currentTime) {
    if (duration !== Infinity) {
      var syncPoint = {
        time: 0,
        segmentIndex: 0
      };

      return syncPoint;
    }
    return null;
  }
},
// Stategy "ProgramDateTime": We have a program-date-time tag in this playlist
{
  name: 'ProgramDateTime',
  run: function run(syncController, playlist, duration, currentTimeline, currentTime) {
    if (syncController.datetimeToDisplayTime && playlist.dateTimeObject) {
      var playlistTime = playlist.dateTimeObject.getTime() / 1000;
      var playlistStart = playlistTime + syncController.datetimeToDisplayTime;
      var syncPoint = {
        time: playlistStart,
        segmentIndex: 0
      };

      return syncPoint;
    }
    return null;
  }
},
// Stategy "Segment": We have a known time mapping for a timeline and a
//                    segment in the current timeline with timing data
{
  name: 'Segment',
  run: function run(syncController, playlist, duration, currentTimeline, currentTime) {
    var segments = playlist.segments || [];
    var syncPoint = null;
    var lastDistance = null;

    currentTime = currentTime || 0;

    for (var i = 0; i < segments.length; i++) {
      var segment = segments[i];

      if (segment.timeline === currentTimeline && typeof segment.start !== 'undefined') {
        var distance = Math.abs(currentTime - segment.start);

        // Once the distance begins to increase, we have passed
        // currentTime and can stop looking for better candidates
        if (lastDistance !== null && lastDistance < distance) {
          break;
        }

        if (!syncPoint || lastDistance === null || lastDistance >= distance) {
          lastDistance = distance;
          syncPoint = {
            time: segment.start,
            segmentIndex: i
          };
        }
      }
    }
    return syncPoint;
  }
},
// Stategy "Discontinuity": We have a discontinuity with a known
//                          display-time
{
  name: 'Discontinuity',
  run: function run(syncController, playlist, duration, currentTimeline, currentTime) {
    var syncPoint = null;

    currentTime = currentTime || 0;

    if (playlist.discontinuityStarts && playlist.discontinuityStarts.length) {
      var lastDistance = null;

      for (var i = 0; i < playlist.discontinuityStarts.length; i++) {
        var segmentIndex = playlist.discontinuityStarts[i];
        var discontinuity = playlist.discontinuitySequence + i + 1;
        var discontinuitySync = syncController.discontinuities[discontinuity];

        if (discontinuitySync) {
          var distance = Math.abs(currentTime - discontinuitySync.time);

          // Once the distance begins to increase, we have passed
          // currentTime and can stop looking for better candidates
          if (lastDistance !== null && lastDistance < distance) {
            break;
          }

          if (!syncPoint || lastDistance === null || lastDistance >= distance) {
            lastDistance = distance;
            syncPoint = {
              time: discontinuitySync.time,
              segmentIndex: segmentIndex
            };
          }
        }
      }
    }
    return syncPoint;
  }
},
// Stategy "Playlist": We have a playlist with a known mapping of
//                     segment index to display time
{
  name: 'Playlist',
  run: function run(syncController, playlist, duration, currentTimeline, currentTime) {
    if (playlist.syncInfo) {
      var syncPoint = {
        time: playlist.syncInfo.time,
        segmentIndex: playlist.syncInfo.mediaSequence - playlist.mediaSequence
      };

      return syncPoint;
    }
    return null;
  }
}];

exports.syncPointStrategies = syncPointStrategies;

var SyncController = (function (_videojs$EventTarget) {
  _inherits(SyncController, _videojs$EventTarget);

  function SyncController() {
    var options = arguments.length <= 0 || arguments[0] === undefined ? {} : arguments[0];

    _classCallCheck(this, SyncController);

    _get(Object.getPrototypeOf(SyncController.prototype), 'constructor', this).call(this);
    // Segment Loader state variables...
    // ...for synching across variants
    this.inspectCache_ = undefined;

    // ...for synching across variants
    this.timelines = [];
    this.discontinuities = [];
    this.datetimeToDisplayTime = null;

    if (options.debug) {
      this.logger_ = _videoJs2['default'].log.bind(_videoJs2['default'], 'sync-controller ->');
    }
  }

  /**
   * Find a sync-point for the playlist specified
   *
   * A sync-point is defined as a known mapping from display-time to
   * a segment-index in the current playlist.
   *
   * @param {Playlist} playlist
   *        The playlist that needs a sync-point
   * @param {Number} duration
   *        Duration of the MediaSource (Infinite if playing a live source)
   * @param {Number} currentTimeline
   *        The last timeline from which a segment was loaded
   * @returns {Object}
   *          A sync-point object
   */

  _createClass(SyncController, [{
    key: 'getSyncPoint',
    value: function getSyncPoint(playlist, duration, currentTimeline, currentTime) {
      var syncPoints = this.runStrategies_(playlist, duration, currentTimeline, currentTime);

      if (!syncPoints.length) {
        // Signal that we need to attempt to get a sync-point manually
        // by fetching a segment in the playlist and constructing
        // a sync-point from that information
        return null;
      }

      // Now find the sync-point that is closest to the currentTime because
      // that should result in the most accurate guess about which segment
      // to fetch
      return this.selectSyncPoint_(syncPoints, { key: 'time', value: currentTime });
    }

    /**
     * Calculate the amount of time that has expired off the playlist during playback
     *
     * @param {Playlist} playlist
     *        Playlist object to calculate expired from
     * @param {Number} duration
     *        Duration of the MediaSource (Infinity if playling a live source)
     * @returns {Number|null}
     *          The amount of time that has expired off the playlist during playback. Null
     *          if no sync-points for the playlist can be found.
     */
  }, {
    key: 'getExpiredTime',
    value: function getExpiredTime(playlist, duration) {
      if (!playlist || !playlist.segments) {
        return null;
      }

      var syncPoints = this.runStrategies_(playlist, duration, playlist.discontinuitySequence, 0);

      // Without sync-points, there is not enough information to determine the expired time
      if (!syncPoints.length) {
        return null;
      }

      var syncPoint = this.selectSyncPoint_(syncPoints, {
        key: 'segmentIndex',
        value: 0
      });

      // If the sync-point is beyond the start of the playlist, we want to subtract the
      // duration from index 0 to syncPoint.segmentIndex instead of adding.
      if (syncPoint.segmentIndex > 0) {
        syncPoint.time *= -1;
      }

      return Math.abs(syncPoint.time + (0, _playlist.sumDurations)(playlist, syncPoint.segmentIndex, 0));
    }

    /**
     * Runs each sync-point strategy and returns a list of sync-points returned by the
     * strategies
     *
     * @private
     * @param {Playlist} playlist
     *        The playlist that needs a sync-point
     * @param {Number} duration
     *        Duration of the MediaSource (Infinity if playing a live source)
     * @param {Number} currentTimeline
     *        The last timeline from which a segment was loaded
     * @returns {Array}
     *          A list of sync-point objects
     */
  }, {
    key: 'runStrategies_',
    value: function runStrategies_(playlist, duration, currentTimeline, currentTime) {
      var syncPoints = [];

      // Try to find a sync-point in by utilizing various strategies...
      for (var i = 0; i < syncPointStrategies.length; i++) {
        var strategy = syncPointStrategies[i];
        var syncPoint = strategy.run(this, playlist, duration, currentTimeline, currentTime);

        if (syncPoint) {
          syncPoint.strategy = strategy.name;
          syncPoints.push({
            strategy: strategy.name,
            syncPoint: syncPoint
          });
          this.logger_('syncPoint found via <' + strategy.name + '>:', syncPoint);
        }
      }

      return syncPoints;
    }

    /**
     * Selects the sync-point nearest the specified target
     *
     * @private
     * @param {Array} syncPoints
     *        List of sync-points to select from
     * @param {Object} target
     *        Object specifying the property and value we are targeting
     * @param {String} target.key
     *        Specifies the property to target. Must be either 'time' or 'segmentIndex'
     * @param {Number} target.value
     *        The value to target for the specified key.
     * @returns {Object}
     *          The sync-point nearest the target
     */
  }, {
    key: 'selectSyncPoint_',
    value: function selectSyncPoint_(syncPoints, target) {
      var bestSyncPoint = syncPoints[0].syncPoint;
      var bestDistance = Math.abs(syncPoints[0].syncPoint[target.key] - target.value);
      var bestStrategy = syncPoints[0].strategy;

      for (var i = 1; i < syncPoints.length; i++) {
        var newDistance = Math.abs(syncPoints[i].syncPoint[target.key] - target.value);

        if (newDistance < bestDistance) {
          bestDistance = newDistance;
          bestSyncPoint = syncPoints[i].syncPoint;
          bestStrategy = syncPoints[i].strategy;
        }
      }

      this.logger_('syncPoint with strategy <' + bestStrategy + '> chosen: ', bestSyncPoint);
      return bestSyncPoint;
    }

    /**
     * Save any meta-data present on the segments when segments leave
     * the live window to the playlist to allow for synchronization at the
     * playlist level later.
     *
     * @param {Playlist} oldPlaylist - The previous active playlist
     * @param {Playlist} newPlaylist - The updated and most current playlist
     */
  }, {
    key: 'saveExpiredSegmentInfo',
    value: function saveExpiredSegmentInfo(oldPlaylist, newPlaylist) {
      var mediaSequenceDiff = newPlaylist.mediaSequence - oldPlaylist.mediaSequence;

      // When a segment expires from the playlist and it has a start time
      // save that information as a possible sync-point reference in future
      for (var i = mediaSequenceDiff - 1; i >= 0; i--) {
        var lastRemovedSegment = oldPlaylist.segments[i];

        if (lastRemovedSegment && typeof lastRemovedSegment.start !== 'undefined') {
          newPlaylist.syncInfo = {
            mediaSequence: oldPlaylist.mediaSequence + i,
            time: lastRemovedSegment.start
          };
          this.logger_('playlist sync:', newPlaylist.syncInfo);
          this.trigger('syncinfoupdate');
          break;
        }
      }
    }

    /**
     * Save the mapping from playlist's ProgramDateTime to display. This should
     * only ever happen once at the start of playback.
     *
     * @param {Playlist} playlist - The currently active playlist
     */
  }, {
    key: 'setDateTimeMapping',
    value: function setDateTimeMapping(playlist) {
      if (!this.datetimeToDisplayTime && playlist.dateTimeObject) {
        var playlistTimestamp = playlist.dateTimeObject.getTime() / 1000;

        this.datetimeToDisplayTime = -playlistTimestamp;
      }
    }

    /**
     * Reset the state of the inspection cache when we do a rendition
     * switch
     */
  }, {
    key: 'reset',
    value: function reset() {
      this.inspectCache_ = undefined;
    }

    /**
     * Probe or inspect a fmp4 or an mpeg2-ts segment to determine the start
     * and end of the segment in it's internal "media time". Used to generate
     * mappings from that internal "media time" to the display time that is
     * shown on the player.
     *
     * @param {SegmentInfo} segmentInfo - The current active request information
     */
  }, {
    key: 'probeSegmentInfo',
    value: function probeSegmentInfo(segmentInfo) {
      var segment = segmentInfo.segment;
      var playlist = segmentInfo.playlist;
      var timingInfo = undefined;

      if (segment.map) {
        timingInfo = this.probeMp4Segment_(segmentInfo);
      } else {
        timingInfo = this.probeTsSegment_(segmentInfo);
      }

      if (timingInfo) {
        if (this.calculateSegmentTimeMapping_(segmentInfo, timingInfo)) {
          this.saveDiscontinuitySyncInfo_(segmentInfo);

          // If the playlist does not have sync information yet, record that information
          // now with segment timing information
          if (!playlist.syncInfo) {
            playlist.syncInfo = {
              mediaSequence: playlist.mediaSequence + segmentInfo.mediaIndex,
              time: segment.start
            };
          }
        }
      }

      return timingInfo;
    }

    /**
     * Probe an fmp4 or an mpeg2-ts segment to determine the start of the segment
     * in it's internal "media time".
     *
     * @private
     * @param {SegmentInfo} segmentInfo - The current active request information
     * @return {object} The start and end time of the current segment in "media time"
     */
  }, {
    key: 'probeMp4Segment_',
    value: function probeMp4Segment_(segmentInfo) {
      var segment = segmentInfo.segment;
      var timescales = _muxJsLibMp4Probe2['default'].timescale(segment.map.bytes);
      var startTime = _muxJsLibMp4Probe2['default'].startTime(timescales, segmentInfo.bytes);

      if (segmentInfo.timestampOffset !== null) {
        segmentInfo.timestampOffset -= startTime;
      }

      return {
        start: startTime,
        end: startTime + segment.duration
      };
    }

    /**
     * Probe an mpeg2-ts segment to determine the start and end of the segment
     * in it's internal "media time".
     *
     * @private
     * @param {SegmentInfo} segmentInfo - The current active request information
     * @return {object} The start and end time of the current segment in "media time"
     */
  }, {
    key: 'probeTsSegment_',
    value: function probeTsSegment_(segmentInfo) {
      var timeInfo = (0, _muxJsLibToolsTsInspectorJs.inspect)(segmentInfo.bytes, this.inspectCache_);
      var segmentStartTime = undefined;
      var segmentEndTime = undefined;

      if (!timeInfo) {
        return null;
      }

      if (timeInfo.video && timeInfo.video.length === 2) {
        this.inspectCache_ = timeInfo.video[1].dts;
        segmentStartTime = timeInfo.video[0].dtsTime;
        segmentEndTime = timeInfo.video[1].dtsTime;
      } else if (timeInfo.audio && timeInfo.audio.length === 2) {
        this.inspectCache_ = timeInfo.audio[1].dts;
        segmentStartTime = timeInfo.audio[0].dtsTime;
        segmentEndTime = timeInfo.audio[1].dtsTime;
      }

      return {
        start: segmentStartTime,
        end: segmentEndTime,
        containsVideo: timeInfo.video && timeInfo.video.length === 2,
        containsAudio: timeInfo.audio && timeInfo.audio.length === 2
      };
    }
  }, {
    key: 'timestampOffsetForTimeline',
    value: function timestampOffsetForTimeline(timeline) {
      if (typeof this.timelines[timeline] === 'undefined') {
        return null;
      }
      return this.timelines[timeline].time;
    }
  }, {
    key: 'mappingForTimeline',
    value: function mappingForTimeline(timeline) {
      if (typeof this.timelines[timeline] === 'undefined') {
        return null;
      }
      return this.timelines[timeline].mapping;
    }

    /**
     * Use the "media time" for a segment to generate a mapping to "display time" and
     * save that display time to the segment.
     *
     * @private
     * @param {SegmentInfo} segmentInfo
     *        The current active request information
     * @param {object} timingInfo
     *        The start and end time of the current segment in "media time"
     * @returns {Boolean}
     *          Returns false if segment time mapping could not be calculated
     */
  }, {
    key: 'calculateSegmentTimeMapping_',
    value: function calculateSegmentTimeMapping_(segmentInfo, timingInfo) {
      var segment = segmentInfo.segment;
      var mappingObj = this.timelines[segmentInfo.timeline];

      if (segmentInfo.timestampOffset !== null) {
        this.logger_('tsO:', segmentInfo.timestampOffset);

        mappingObj = {
          time: segmentInfo.startOfSegment,
          mapping: segmentInfo.startOfSegment - timingInfo.start
        };
        this.timelines[segmentInfo.timeline] = mappingObj;
        this.trigger('timestampoffset');

        segment.start = segmentInfo.startOfSegment;
        segment.end = timingInfo.end + mappingObj.mapping;
      } else if (mappingObj) {
        segment.start = timingInfo.start + mappingObj.mapping;
        segment.end = timingInfo.end + mappingObj.mapping;
      } else {
        return false;
      }

      return true;
    }

    /**
     * Each time we have discontinuity in the playlist, attempt to calculate the location
     * in display of the start of the discontinuity and save that. We also save an accuracy
     * value so that we save values with the most accuracy (closest to 0.)
     *
     * @private
     * @param {SegmentInfo} segmentInfo - The current active request information
     */
  }, {
    key: 'saveDiscontinuitySyncInfo_',
    value: function saveDiscontinuitySyncInfo_(segmentInfo) {
      var playlist = segmentInfo.playlist;
      var segment = segmentInfo.segment;

      // If the current segment is a discontinuity then we know exactly where
      // the start of the range and it's accuracy is 0 (greater accuracy values
      // mean more approximation)
      if (segment.discontinuity) {
        this.discontinuities[segment.timeline] = {
          time: segment.start,
          accuracy: 0
        };
      } else if (playlist.discontinuityStarts.length) {
        // Search for future discontinuities that we can provide better timing
        // information for and save that information for sync purposes
        for (var i = 0; i < playlist.discontinuityStarts.length; i++) {
          var segmentIndex = playlist.discontinuityStarts[i];
          var discontinuity = playlist.discontinuitySequence + i + 1;
          var mediaIndexDiff = segmentIndex - segmentInfo.mediaIndex;
          var accuracy = Math.abs(mediaIndexDiff);

          if (!this.discontinuities[discontinuity] || this.discontinuities[discontinuity].accuracy > accuracy) {
            var time = undefined;

            if (mediaIndexDiff < 0) {
              time = segment.start - (0, _playlist.sumDurations)(playlist, segmentInfo.mediaIndex, segmentIndex);
            } else {
              time = segment.end + (0, _playlist.sumDurations)(playlist, segmentInfo.mediaIndex + 1, segmentIndex);
            }

            this.discontinuities[discontinuity] = {
              time: time,
              accuracy: accuracy
            };
          }
        }
      }
    }

    /**
     * A debugging logger noop that is set to console.log only if debugging
     * is enabled globally
     *
     * @private
     */
  }, {
    key: 'logger_',
    value: function logger_() {}
  }]);

  return SyncController;
})(_videoJs2['default'].EventTarget);

exports['default'] = SyncController;