Source: lib/media/media_source_engine.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.media.MediaSourceEngine');
  9. goog.require('goog.asserts');
  10. goog.require('shaka.log');
  11. goog.require('shaka.media.ContentWorkarounds');
  12. goog.require('shaka.media.IClosedCaptionParser');
  13. goog.require('shaka.media.TimeRangesUtils');
  14. goog.require('shaka.media.Transmuxer');
  15. goog.require('shaka.text.TextEngine');
  16. goog.require('shaka.util.Destroyer');
  17. goog.require('shaka.util.Error');
  18. goog.require('shaka.util.EventManager');
  19. goog.require('shaka.util.Functional');
  20. goog.require('shaka.util.IDestroyable');
  21. goog.require('shaka.util.ManifestParserUtils');
  22. goog.require('shaka.util.MimeUtils');
  23. goog.require('shaka.util.Platform');
  24. goog.require('shaka.util.PublicPromise');
  27. /**
  28.  * @summary
  29.  * MediaSourceEngine wraps all operations on MediaSource and SourceBuffers.
  30.  * All asynchronous operations return a Promise, and all operations are
  31.  * internally synchronized and serialized as needed.  Operations that can
  32.  * be done in parallel will be done in parallel.
  33.  *
  34.  * @implements {shaka.util.IDestroyable}
  35.  */
  36. shaka.media.MediaSourceEngine = class {
  37.   /**
  38.    * @param {HTMLMediaElement} video The video element, whose source is tied to
  39.    *   MediaSource during the lifetime of the MediaSourceEngine.
  40.    * @param {!shaka.media.IClosedCaptionParser} closedCaptionParser
  41.    *    The closed caption parser that should be used to parser closed captions
  42.    *    from the video stream. MediaSourceEngine takes ownership of the parser.
  43.    *    When MediaSourceEngine is destroyed, it will destroy the parser.
  44.    * @param {!shaka.extern.TextDisplayer} textDisplayer
  45.    *    The text displayer that will be used with the text engine.
  46.    *    MediaSourceEngine takes ownership of the displayer. When
  47.    *    MediaSourceEngine is destroyed, it will destroy the displayer.
  48.    * @param {!function(!Array.<shaka.extern.ID3Metadata>, number, ?number)=}
  49.    *    onMetadata
  50.    */
  51.   constructor(video, closedCaptionParser, textDisplayer, onMetadata) {
  52.     /** @private {HTMLMediaElement} */
  53.     this.video_ = video;
  55.     /** @private {shaka.extern.TextDisplayer} */
  56.     this.textDisplayer_ = textDisplayer;
  58.     /** @private {!Object.<shaka.util.ManifestParserUtils.ContentType,
  59.                            SourceBuffer>} */
  60.     this.sourceBuffers_ = {};
  62.     /** @private {!Object.<shaka.util.ManifestParserUtils.ContentType,
  63.                            string>} */
  64.     this.sourceBufferTypes_ = {};
  67.     /** @private {!Object.<shaka.util.ManifestParserUtils.ContentType,
  68.                            boolean>} */
  69.     this.expectedEncryption_ = {};
  71.     /** @private {shaka.text.TextEngine} */
  72.     this.textEngine_ = null;
  74.     const onMetadataNoOp = (metadata, timestampOffset, segmentEnd) => {};
  76.     /** @private {!function(!Array.<shaka.extern.ID3Metadata>,
  77.                     number, ?number)} */
  78.     this.onMetadata_ = onMetadata || onMetadataNoOp;
  80.     /**
  81.      * @private {!Object.<string,
  82.      *                    !Array.<shaka.media.MediaSourceEngine.Operation>>}
  83.      */
  84.     this.queues_ = {};
  86.     /** @private {shaka.util.EventManager} */
  87.     this.eventManager_ = new shaka.util.EventManager();
  89.     /** @private {!Object.<string, !shaka.media.Transmuxer>} */
  90.     this.transmuxers_ = {};
  92.     /** @private {shaka.media.IClosedCaptionParser} */
  93.     this.captionParser_ = closedCaptionParser;
  95.     /** @private {!shaka.util.PublicPromise} */
  96.     this.mediaSourceOpen_ = new shaka.util.PublicPromise();
  98.     /** @private {MediaSource} */
  99.     this.mediaSource_ = this.createMediaSource(this.mediaSourceOpen_);
  101.     /** @type {!shaka.util.Destroyer} */
  102.     this.destroyer_ = new shaka.util.Destroyer(() => this.doDestroy_());
  104.     /** @private {string} */
  105.     this.url_ = '';
  106.   }
  108.   /**
  109.    * Create a MediaSource object, attach it to the video element, and return it.
  110.    * Resolves the given promise when the MediaSource is ready.
  111.    *
  112.    * Replaced by unit tests.
  113.    *
  114.    * @param {!shaka.util.PublicPromise} p
  115.    * @return {!MediaSource}
  116.    */
  117.   createMediaSource(p) {
  118.     const mediaSource = new MediaSource();
  120.     // Set up MediaSource on the video element.
  121.     this.eventManager_.listenOnce(
  122.         mediaSource, 'sourceopen', () => this.onSourceOpen_(p));
  124.     // Store the object URL for releasing it later.
  125.     this.url_ = shaka.media.MediaSourceEngine.createObjectURL(mediaSource);
  127.     this.video_.src = this.url_;
  129.     return mediaSource;
  130.   }
  132.   /**
  133.    * @param {!shaka.util.PublicPromise} p
  134.    * @private
  135.    */
  136.   onSourceOpen_(p) {
  137.     // Release the object URL that was previously created, to prevent memory
  138.     // leak.
  139.     // createObjectURL creates a strong reference to the MediaSource object
  140.     // inside the browser.  Setting the src of the video then creates another
  141.     // reference within the video element.  revokeObjectURL will remove the
  142.     // strong reference to the MediaSource object, and allow it to be
  143.     // garbage-collected later.
  144.     URL.revokeObjectURL(this.url_);
  145.     p.resolve();
  146.   }
  148.   /**
  149.    * Checks if a certain type is supported.
  150.    *
  151.    * @param {shaka.extern.Stream} stream
  152.    * @return {boolean}
  153.    */
  154.   static isStreamSupported(stream) {
  155.     const fullMimeType = shaka.util.MimeUtils.getFullType(
  156.         stream.mimeType, stream.codecs);
  157.     const extendedMimeType = shaka.util.MimeUtils.getExtendedType(stream);
  158.     return shaka.text.TextEngine.isTypeSupported(fullMimeType) ||
  159.         MediaSource.isTypeSupported(extendedMimeType) ||
  160.         shaka.media.Transmuxer.isSupported(fullMimeType, stream.type);
  161.   }
  163.   /**
  164.    * Returns a map of MediaSource support for well-known types.
  165.    *
  166.    * @return {!Object.<string, boolean>}
  167.    */
  168.   static probeSupport() {
  169.     const testMimeTypes = [
  170.       // MP4 types
  171.       'video/mp4; codecs="avc1.42E01E"',
  172.       'video/mp4; codecs="avc3.42E01E"',
  173.       'video/mp4; codecs="hev1.1.6.L93.90"',
  174.       'video/mp4; codecs="hvc1.1.6.L93.90"',
  175.       'video/mp4; codecs="hev1.2.4.L153.B0"; eotf="smpte2084"',  // HDR HEVC
  176.       'video/mp4; codecs="hvc1.2.4.L153.B0"; eotf="smpte2084"',  // HDR HEVC
  177.       'video/mp4; codecs="vp9"',
  178.       'video/mp4; codecs="vp09.00.10.08"',
  179.       'video/mp4; codecs="av01.0.01M.08"',
  180.       'audio/mp4; codecs="mp4a.40.2"',
  181.       'audio/mp4; codecs="ac-3"',
  182.       'audio/mp4; codecs="ec-3"',
  183.       'audio/mp4; codecs="opus"',
  184.       'audio/mp4; codecs="flac"',
  185.       // WebM types
  186.       'video/webm; codecs="vp8"',
  187.       'video/webm; codecs="vp9"',
  188.       'video/webm; codecs="vp09.00.10.08"',
  189.       'audio/webm; codecs="vorbis"',
  190.       'audio/webm; codecs="opus"',
  191.       // MPEG2 TS types (video/ is also used for audio: https://bit.ly/TsMse)
  192.       'video/mp2t; codecs="avc1.42E01E"',
  193.       'video/mp2t; codecs="avc3.42E01E"',
  194.       'video/mp2t; codecs="hvc1.1.6.L93.90"',
  195.       'video/mp2t; codecs="mp4a.40.2"',
  196.       'video/mp2t; codecs="ac-3"',
  197.       'video/mp2t; codecs="ec-3"',
  198.       // WebVTT types
  199.       'text/vtt',
  200.       'application/mp4; codecs="wvtt"',
  201.       // TTML types
  202.       'application/ttml+xml',
  203.       'application/mp4; codecs="stpp"',
  204.     ];
  206.     const support = {};
  207.     for (const type of testMimeTypes) {
  208.       if (shaka.util.Platform.supportsMediaSource()) {
  209.         // Our TextEngine is only effective for MSE platforms at the moment.
  210.         if (shaka.text.TextEngine.isTypeSupported(type)) {
  211.           support[type] = true;
  212.         } else {
  213.           support[type] = MediaSource.isTypeSupported(type) ||
  214.                           shaka.media.Transmuxer.isSupported(type);
  215.         }
  216.       } else {
  217.         support[type] = shaka.util.Platform.supportsMediaType(type);
  218.       }
  220.       const basicType = type.split(';')[0];
  221.       support[basicType] = support[basicType] || support[type];
  222.     }
  224.     return support;
  225.   }
  227.   /** @override */
  228.   destroy() {
  229.     return this.destroyer_.destroy();
  230.   }
  232.   /** @private */
  233.   async doDestroy_() {
  234.     const Functional = shaka.util.Functional;
  236.     const cleanup = [];
  238.     for (const contentType in this.queues_) {
  239.       // Make a local copy of the queue and the first item.
  240.       const q = this.queues_[contentType];
  241.       const inProgress = q[0];
  243.       // Drop everything else out of the original queue.
  244.       this.queues_[contentType] = q.slice(0, 1);
  246.       // We will wait for this item to complete/fail.
  247.       if (inProgress) {
  248.         cleanup.push(inProgress.p.catch(Functional.noop));
  249.       }
  251.       // The rest will be rejected silently if possible.
  252.       for (const item of q.slice(1)) {
  253.         item.p.reject(shaka.util.Destroyer.destroyedError());
  254.       }
  255.     }
  257.     if (this.textEngine_) {
  258.       cleanup.push(this.textEngine_.destroy());
  259.     }
  260.     if (this.textDisplayer_) {
  261.       cleanup.push(this.textDisplayer_.destroy());
  262.     }
  264.     for (const contentType in this.transmuxers_) {
  265.       cleanup.push(this.transmuxers_[contentType].destroy());
  266.     }
  269.     await Promise.all(cleanup);
  270.     if (this.eventManager_) {
  271.       this.eventManager_.release();
  272.       this.eventManager_ = null;
  273.     }
  275.     if (this.video_) {
  276.       // "unload" the video element.
  277.       this.video_.removeAttribute('src');
  278.       this.video_.load();
  279.       this.video_ = null;
  280.     }
  282.     this.mediaSource_ = null;
  283.     this.textEngine_ = null;
  284.     this.textDisplayer_ = null;
  285.     this.sourceBuffers_ = {};
  286.     this.transmuxers_ = {};
  287.     this.captionParser_ = null;
  288.     if (goog.DEBUG) {
  289.       for (const contentType in this.queues_) {
  290.         goog.asserts.assert(
  291.             this.queues_[contentType].length == 0,
  292.             contentType + ' queue should be empty after destroy!');
  293.       }
  294.     }
  295.     this.queues_ = {};
  296.   }
  298.   /**
  299.    * @return {!Promise} Resolved when MediaSource is open and attached to the
  300.    *   media element.  This process is actually initiated by the constructor.
  301.    */
  302.   open() {
  303.     return this.mediaSourceOpen_;
  304.   }
  306.   /**
  307.    * Initialize MediaSourceEngine.
  308.    *
  309.    * Note that it is not valid to call this multiple times, except to add or
  310.    * reinitialize text streams.
  311.    *
  312.    * @param {!Map.<shaka.util.ManifestParserUtils.ContentType,
  313.    *               shaka.extern.Stream>} streamsByType
  314.    *   A map of content types to streams.  All streams must be supported
  315.    *   according to MediaSourceEngine.isStreamSupported.
  316.    * @param {boolean} forceTransmuxTS
  317.    *   If true, this will transmux TS content even if it is natively supported.
  318.    *
  319.    * @return {!Promise}
  320.    */
  321.   async init(streamsByType, forceTransmuxTS) {
  322.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  324.     await this.mediaSourceOpen_;
  326.     for (const contentType of streamsByType.keys()) {
  327.       const stream = streamsByType.get(contentType);
  328.       goog.asserts.assert(
  329.           shaka.media.MediaSourceEngine.isStreamSupported(stream),
  330.           'Type negotiation should happen before MediaSourceEngine.init!');
  332.       let mimeType = shaka.util.MimeUtils.getFullType(
  333.           stream.mimeType, stream.codecs);
  334.       if (contentType == ContentType.TEXT) {
  335.         this.reinitText(mimeType);
  336.       } else {
  337.         if ((forceTransmuxTS || !MediaSource.isTypeSupported(mimeType)) &&
  338.             shaka.media.Transmuxer.isSupported(mimeType, contentType)) {
  339.           this.transmuxers_[contentType] = new shaka.media.Transmuxer();
  340.           mimeType =
  341.               shaka.media.Transmuxer.convertTsCodecs(contentType, mimeType);
  342.         }
  343.         const sourceBuffer = this.mediaSource_.addSourceBuffer(mimeType);
  344.         this.eventManager_.listen(
  345.             sourceBuffer, 'error',
  346.             () => this.onError_(contentType));
  347.         this.eventManager_.listen(
  348.             sourceBuffer, 'updateend',
  349.             () => this.onUpdateEnd_(contentType));
  350.         this.sourceBuffers_[contentType] = sourceBuffer;
  351.         this.sourceBufferTypes_[contentType] = mimeType;
  352.         this.queues_[contentType] = [];
  353.         this.expectedEncryption_[contentType] = !!stream.drmInfos.length;
  354.       }
  355.     }
  356.   }
  358.   /**
  359.    * Reinitialize the TextEngine for a new text type.
  360.    * @param {string} mimeType
  361.    */
  362.   reinitText(mimeType) {
  363.     if (!this.textEngine_) {
  364.       this.textEngine_ = new shaka.text.TextEngine(this.textDisplayer_);
  365.     }
  366.     this.textEngine_.initParser(mimeType);
  367.   }
  369.   /**
  370.    * @return {boolean} True if the MediaSource is in an "ended" state, or if the
  371.    *   object has been destroyed.
  372.    */
  373.   ended() {
  374.     return this.mediaSource_ ? this.mediaSource_.readyState == 'ended' : true;
  375.   }
  377.   /**
  378.    * Gets the first timestamp in buffer for the given content type.
  379.    *
  380.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  381.    * @return {?number} The timestamp in seconds, or null if nothing is buffered.
  382.    */
  383.   bufferStart(contentType) {
  384.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  385.     if (contentType == ContentType.TEXT) {
  386.       return this.textEngine_.bufferStart();
  387.     }
  388.     return shaka.media.TimeRangesUtils.bufferStart(
  389.         this.getBuffered_(contentType));
  390.   }
  392.   /**
  393.    * Gets the last timestamp in buffer for the given content type.
  394.    *
  395.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  396.    * @return {?number} The timestamp in seconds, or null if nothing is buffered.
  397.    */
  398.   bufferEnd(contentType) {
  399.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  400.     if (contentType == ContentType.TEXT) {
  401.       return this.textEngine_.bufferEnd();
  402.     }
  403.     return shaka.media.TimeRangesUtils.bufferEnd(
  404.         this.getBuffered_(contentType));
  405.   }
  407.   /**
  408.    * Determines if the given time is inside the buffered range of the given
  409.    * content type.
  410.    *
  411.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  412.    * @param {number} time Playhead time
  413.    * @param {number=} smallGapLimit
  414.    * @return {boolean}
  415.    */
  416.   isBuffered(contentType, time, smallGapLimit) {
  417.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  418.     if (contentType == ContentType.TEXT) {
  419.       return this.textEngine_.isBuffered(time);
  420.     } else {
  421.       const buffered = this.getBuffered_(contentType);
  422.       return shaka.media.TimeRangesUtils.isBuffered(
  423.           buffered, time, smallGapLimit);
  424.     }
  425.   }
  427.   /**
  428.    * Computes how far ahead of the given timestamp is buffered for the given
  429.    * content type.
  430.    *
  431.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  432.    * @param {number} time
  433.    * @return {number} The amount of time buffered ahead in seconds.
  434.    */
  435.   bufferedAheadOf(contentType, time) {
  436.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  437.     if (contentType == ContentType.TEXT) {
  438.       return this.textEngine_.bufferedAheadOf(time);
  439.     } else {
  440.       const buffered = this.getBuffered_(contentType);
  441.       return shaka.media.TimeRangesUtils.bufferedAheadOf(buffered, time);
  442.     }
  443.   }
  445.   /**
  446.    * Returns info about what is currently buffered.
  447.    * @return {shaka.extern.BufferedInfo}
  448.    */
  449.   getBufferedInfo() {
  450.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  451.     const TimeRangeUtils = shaka.media.TimeRangesUtils;
  453.     const info = {
  454.       total: TimeRangeUtils.getBufferedInfo(this.video_.buffered),
  455.       audio: TimeRangeUtils.getBufferedInfo(
  456.           this.getBuffered_(ContentType.AUDIO)),
  457.       video: TimeRangeUtils.getBufferedInfo(
  458.           this.getBuffered_(ContentType.VIDEO)),
  459.       text: [],
  460.     };
  462.     if (this.textEngine_) {
  463.       const start = this.textEngine_.bufferStart();
  464.       const end = this.textEngine_.bufferEnd();
  466.       if (start != null && end != null) {
  467.         info.text.push({start: start, end: end});
  468.       }
  469.     }
  470.     return info;
  471.   }
  473.   /**
  474.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  475.    * @return {TimeRanges} The buffered ranges for the given content type, or
  476.    *   null if the buffered ranges could not be obtained.
  477.    * @private
  478.    */
  479.   getBuffered_(contentType) {
  480.     try {
  481.       return this.sourceBuffers_[contentType].buffered;
  482.     } catch (exception) {
  483.       if (contentType in this.sourceBuffers_) {
  484.         // Note: previous MediaSource errors may cause access to |buffered| to
  485.         // throw.
  486.         shaka.log.error('failed to get buffered range for ' + contentType,
  487.             exception);
  488.       }
  489.       return null;
  490.     }
  491.   }
  493.   /**
  494.    * Enqueue an operation to append data to the SourceBuffer.
  495.    * Start and end times are needed for TextEngine, but not for MediaSource.
  496.    * Start and end times may be null for initialization segments; if present
  497.    * they are relative to the presentation timeline.
  498.    *
  499.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  500.    * @param {!BufferSource} data
  501.    * @param {?number} startTime relative to the start of the presentation
  502.    * @param {?number} endTime relative to the start of the presentation
  503.    * @param {?boolean} hasClosedCaptions True if the buffer contains CEA closed
  504.    * captions
  505.    * @return {!Promise}
  506.    */
  507.   async appendBuffer(contentType, data, startTime, endTime, hasClosedCaptions) {
  508.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  510.     if (contentType == ContentType.TEXT) {
  511.       await this.textEngine_.appendBuffer(data, startTime, endTime);
  512.     } else if (this.transmuxers_[contentType]) {
  513.       const transmuxedData =
  514.           await this.transmuxers_[contentType].transmux(data);
  515.       // For HLS CEA-608/708 CLOSED-CAPTIONS, text data is embedded in
  516.       // the video stream, so textEngine may not have been initialized.
  517.       if (!this.textEngine_) {
  518.         this.reinitText('text/vtt');
  519.       }
  521.       if (transmuxedData.metadata) {
  522.         const timestampOffset =
  523.             this.sourceBuffers_[contentType].timestampOffset;
  524.         this.onMetadata_(transmuxedData.metadata, timestampOffset, endTime);
  525.       }
  526.       // This doesn't work for native TS support (ex. Edge/Chromecast),
  527.       // since no transmuxing is needed for native TS.
  528.       if (transmuxedData.captions && transmuxedData.captions.length) {
  529.         const videoOffset =
  530.         this.sourceBuffers_[ContentType.VIDEO].timestampOffset;
  531.         const closedCaptions = this.textEngine_
  532.             .convertMuxjsCaptionsToShakaCaptions(transmuxedData.captions);
  533.         this.textEngine_.storeAndAppendClosedCaptions(
  534.             closedCaptions, startTime, endTime, videoOffset);
  535.       }
  537.       let transmuxedSegment = transmuxedData.data;
  538.       transmuxedSegment = this.workAroundBrokenPlatforms_(
  539.           transmuxedSegment, startTime, contentType);
  541.       await this.enqueueOperation_(
  542.           contentType, () => this.append_(contentType, transmuxedSegment));
  543.     } else if (hasClosedCaptions) {
  544.       if (!this.textEngine_) {
  545.         this.reinitText('text/vtt');
  546.       }
  547.       // If it is the init segment for closed captions, initialize the closed
  548.       // caption parser.
  549.       if (startTime == null && endTime == null) {
  550.         this.captionParser_.init(data);
  551.       } else {
  552.         const closedCaptions = this.captionParser_.parseFrom(data);
  553.         if (closedCaptions.length) {
  554.           const videoOffset =
  555.             this.sourceBuffers_[ContentType.VIDEO].timestampOffset;
  556.           this.textEngine_.storeAndAppendClosedCaptions(
  557.               closedCaptions, startTime, endTime, videoOffset);
  558.         }
  559.       }
  561.       data = this.workAroundBrokenPlatforms_(data, startTime, contentType);
  563.       await this.enqueueOperation_(
  564.           contentType,
  565.           () => this.append_(contentType, data));
  566.     } else {
  567.       data = this.workAroundBrokenPlatforms_(data, startTime, contentType);
  569.       await this.enqueueOperation_(
  570.           contentType,
  571.           () => this.append_(contentType, data));
  572.     }
  573.   }
  575.   /**
  576.    * Set the selected closed captions Id and language.
  577.    *
  578.    * @param {string} id
  579.    */
  580.   setSelectedClosedCaptionId(id) {
  581.     const VIDEO = shaka.util.ManifestParserUtils.ContentType.VIDEO;
  582.     const videoBufferEndTime = this.bufferEnd(VIDEO) || 0;
  583.     this.textEngine_.setSelectedClosedCaptionId(id, videoBufferEndTime);
  584.   }
  586.   /** Disable embedded closed captions. */
  587.   clearSelectedClosedCaptionId() {
  588.     if (this.textEngine_) {
  589.       this.textEngine_.setSelectedClosedCaptionId('', 0);
  590.     }
  591.   }
  593.   /**
  594.    * Enqueue an operation to remove data from the SourceBuffer.
  595.    *
  596.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  597.    * @param {number} startTime relative to the start of the presentation
  598.    * @param {number} endTime relative to the start of the presentation
  599.    * @return {!Promise}
  600.    */
  601.   async remove(contentType, startTime, endTime) {
  602.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  603.     if (contentType == ContentType.TEXT) {
  604.       await this.textEngine_.remove(startTime, endTime);
  605.     } else {
  606.       await this.enqueueOperation_(
  607.           contentType,
  608.           () => this.remove_(contentType, startTime, endTime));
  609.     }
  610.   }
  612.   /**
  613.    * Enqueue an operation to clear the SourceBuffer.
  614.    *
  615.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  616.    * @return {!Promise}
  617.    */
  618.   async clear(contentType) {
  619.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  620.     if (contentType == ContentType.TEXT) {
  621.       if (!this.textEngine_) {
  622.         return;
  623.       }
  624.       await this.textEngine_.remove(0, Infinity);
  625.     } else {
  626.       // Note that not all platforms allow clearing to Infinity.
  627.       await this.enqueueOperation_(
  628.           contentType,
  629.           () => this.remove_(contentType, 0, this.mediaSource_.duration));
  630.     }
  631.   }
  633.   /**
  634.    * Fully reset the state of the caption parser owned by MediaSourceEngine.
  635.    */
  636.   resetCaptionParser() {
  637.     this.captionParser_.reset();
  638.   }
  640.   /**
  641.    * Enqueue an operation to flush the SourceBuffer.
  642.    * This is a workaround for what we believe is a Chromecast bug.
  643.    *
  644.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  645.    * @return {!Promise}
  646.    */
  647.   async flush(contentType) {
  648.     // Flush the pipeline.  Necessary on Chromecast, even though we have removed
  649.     // everything.
  650.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  651.     if (contentType == ContentType.TEXT) {
  652.       // Nothing to flush for text.
  653.       return;
  654.     }
  655.     await this.enqueueOperation_(
  656.         contentType,
  657.         () => this.flush_(contentType));
  658.   }
  660.   /**
  661.    * Sets the timestamp offset and append window end for the given content type.
  662.    *
  663.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  664.    * @param {number} timestampOffset The timestamp offset.  Segments which start
  665.    *   at time t will be inserted at time t + timestampOffset instead.  This
  666.    *   value does not affect segments which have already been inserted.
  667.    * @param {number} appendWindowStart The timestamp to set the append window
  668.    *   start to.  For future appends, frames/samples with timestamps less than
  669.    *   this value will be dropped.
  670.    * @param {number} appendWindowEnd The timestamp to set the append window end
  671.    *   to.  For future appends, frames/samples with timestamps greater than this
  672.    *   value will be dropped.
  673.    * @return {!Promise}
  674.    */
  675.   async setStreamProperties(
  676.       contentType, timestampOffset, appendWindowStart, appendWindowEnd) {
  677.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  678.     if (contentType == ContentType.TEXT) {
  679.       this.textEngine_.setTimestampOffset(timestampOffset);
  680.       this.textEngine_.setAppendWindow(appendWindowStart, appendWindowEnd);
  681.       return;
  682.     }
  684.     await Promise.all([
  685.       // Queue an abort() to help MSE splice together overlapping segments.
  686.       // We set appendWindowEnd when we change periods in DASH content, and the
  687.       // period transition may result in overlap.
  688.       //
  689.       // An abort() also helps with MPEG2-TS.  When we append a TS segment, we
  690.       // always enter a PARSING_MEDIA_SEGMENT state and we can't change the
  691.       // timestamp offset.  By calling abort(), we reset the state so we can
  692.       // set it.
  693.       this.enqueueOperation_(
  694.           contentType,
  695.           () => this.abort_(contentType)),
  696.       this.enqueueOperation_(
  697.           contentType,
  698.           () => this.setTimestampOffset_(contentType, timestampOffset)),
  699.       this.enqueueOperation_(
  700.           contentType,
  701.           () => this.setAppendWindow_(
  702.               contentType, appendWindowStart, appendWindowEnd)),
  703.     ]);
  704.   }
  706.   /**
  707.    * @param {string=} reason Valid reasons are 'network' and 'decode'.
  708.    * @return {!Promise}
  709.    * @see http://w3c.github.io/media-source/#idl-def-EndOfStreamError
  710.    */
  711.   async endOfStream(reason) {
  712.     await this.enqueueBlockingOperation_(() => {
  713.       // If endOfStream() has already been called on the media source,
  714.       // don't call it again.
  715.       if (this.ended()) {
  716.         return;
  717.       }
  718.       // Tizen won't let us pass undefined, but it will let us omit the
  719.       // argument.
  720.       if (reason) {
  721.         this.mediaSource_.endOfStream(reason);
  722.       } else {
  723.         this.mediaSource_.endOfStream();
  724.       }
  725.     });
  726.   }
  728.   /**
  729.    * We only support increasing duration at this time.  Decreasing duration
  730.    * causes the MSE removal algorithm to run, which results in an 'updateend'
  731.    * event.  Supporting this scenario would be complicated, and is not currently
  732.    * needed.
  733.    *
  734.    * @param {number} duration
  735.    * @return {!Promise}
  736.    */
  737.   async setDuration(duration) {
  738.     goog.asserts.assert(
  739.         isNaN(this.mediaSource_.duration) ||
  740.             this.mediaSource_.duration <= duration,
  741.         'duration cannot decrease: ' + this.mediaSource_.duration + ' -> ' +
  742.             duration);
  743.     await this.enqueueBlockingOperation_(() => {
  744.       this.mediaSource_.duration = duration;
  745.     });
  746.   }
  748.   /**
  749.    * Get the current MediaSource duration.
  750.    *
  751.    * @return {number}
  752.    */
  753.   getDuration() {
  754.     return this.mediaSource_.duration;
  755.   }
  757.   /**
  758.    * Append data to the SourceBuffer.
  759.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  760.    * @param {BufferSource} data
  761.    * @private
  762.    */
  763.   append_(contentType, data) {
  764.     // This will trigger an 'updateend' event.
  765.     this.sourceBuffers_[contentType].appendBuffer(data);
  766.   }
  768.   /**
  769.    * Remove data from the SourceBuffer.
  770.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  771.    * @param {number} startTime relative to the start of the presentation
  772.    * @param {number} endTime relative to the start of the presentation
  773.    * @private
  774.    */
  775.   remove_(contentType, startTime, endTime) {
  776.     if (endTime <= startTime) {
  777.       // Ignore removal of inverted or empty ranges.
  778.       // Fake 'updateend' event to resolve the operation.
  779.       this.onUpdateEnd_(contentType);
  780.       return;
  781.     }
  783.     // This will trigger an 'updateend' event.
  784.     this.sourceBuffers_[contentType].remove(startTime, endTime);
  785.   }
  787.   /**
  788.    * Call abort() on the SourceBuffer.
  789.    * This resets MSE's last_decode_timestamp on all track buffers, which should
  790.    * trigger the splicing logic for overlapping segments.
  791.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  792.    * @private
  793.    */
  794.   abort_(contentType) {
  795.     // Save the append window, which is reset on abort().
  796.     const appendWindowStart =
  797.         this.sourceBuffers_[contentType].appendWindowStart;
  798.     const appendWindowEnd = this.sourceBuffers_[contentType].appendWindowEnd;
  800.     // This will not trigger an 'updateend' event, since nothing is happening.
  801.     // This is only to reset MSE internals, not to abort an actual operation.
  802.     this.sourceBuffers_[contentType].abort();
  804.     // Restore the append window.
  805.     this.sourceBuffers_[contentType].appendWindowStart = appendWindowStart;
  806.     this.sourceBuffers_[contentType].appendWindowEnd = appendWindowEnd;
  808.     // Fake an 'updateend' event to resolve the operation.
  809.     this.onUpdateEnd_(contentType);
  810.   }
  812.   /**
  813.    * Nudge the playhead to force the media pipeline to be flushed.
  814.    * This seems to be necessary on Chromecast to get new content to replace old
  815.    * content.
  816.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  817.    * @private
  818.    */
  819.   flush_(contentType) {
  820.     // Never use flush_ if there's data.  It causes a hiccup in playback.
  821.     goog.asserts.assert(
  822.         this.video_.buffered.length == 0, 'MediaSourceEngine.flush_ should ' +
  823.         'only be used after clearing all data!');
  825.     // Seeking forces the pipeline to be flushed.
  826.     this.video_.currentTime -= 0.001;
  828.     // Fake an 'updateend' event to resolve the operation.
  829.     this.onUpdateEnd_(contentType);
  830.   }
  832.   /**
  833.    * Set the SourceBuffer's timestamp offset.
  834.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  835.    * @param {number} timestampOffset
  836.    * @private
  837.    */
  838.   setTimestampOffset_(contentType, timestampOffset) {
  839.     // Work around for
  840.     // https://github.com/shaka-project/shaka-player/issues/1281:
  841.     // TODO(https://bit.ly/2ttKiBU): follow up when this is fixed in Edge
  842.     if (timestampOffset < 0) {
  843.       // Try to prevent rounding errors in Edge from removing the first
  844.       // keyframe.
  845.       timestampOffset += 0.001;
  846.     }
  848.     this.sourceBuffers_[contentType].timestampOffset = timestampOffset;
  850.     // Fake an 'updateend' event to resolve the operation.
  851.     this.onUpdateEnd_(contentType);
  852.   }
  854.   /**
  855.    * Set the SourceBuffer's append window end.
  856.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  857.    * @param {number} appendWindowStart
  858.    * @param {number} appendWindowEnd
  859.    * @private
  860.    */
  861.   setAppendWindow_(contentType, appendWindowStart, appendWindowEnd) {
  862.     // You can't set start > end, so first set start to 0, then set the new
  863.     // end, then set the new start.  That way, there are no intermediate
  864.     // states which are invalid.
  865.     this.sourceBuffers_[contentType].appendWindowStart = 0;
  866.     this.sourceBuffers_[contentType].appendWindowEnd = appendWindowEnd;
  867.     this.sourceBuffers_[contentType].appendWindowStart = appendWindowStart;
  869.     // Fake an 'updateend' event to resolve the operation.
  870.     this.onUpdateEnd_(contentType);
  871.   }
  873.   /**
  874.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  875.    * @private
  876.    */
  877.   onError_(contentType) {
  878.     const operation = this.queues_[contentType][0];
  879.     goog.asserts.assert(operation, 'Spurious error event!');
  880.     goog.asserts.assert(!this.sourceBuffers_[contentType].updating,
  881.         'SourceBuffer should not be updating on error!');
  882.     const code = this.video_.error ? this.video_.error.code : 0;
  883.     operation.p.reject(new shaka.util.Error(
  884.         shaka.util.Error.Severity.CRITICAL,
  885.         shaka.util.Error.Category.MEDIA,
  886.         shaka.util.Error.Code.MEDIA_SOURCE_OPERATION_FAILED,
  887.         code));
  888.     // Do not pop from queue.  An 'updateend' event will fire next, and to
  889.     // avoid synchronizing these two event handlers, we will allow that one to
  890.     // pop from the queue as normal.  Note that because the operation has
  891.     // already been rejected, the call to resolve() in the 'updateend' handler
  892.     // will have no effect.
  893.   }
  895.   /**
  896.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  897.    * @private
  898.    */
  899.   onUpdateEnd_(contentType) {
  900.     const operation = this.queues_[contentType][0];
  901.     goog.asserts.assert(operation, 'Spurious updateend event!');
  902.     if (!operation) {
  903.       return;
  904.     }
  905.     goog.asserts.assert(!this.sourceBuffers_[contentType].updating,
  906.         'SourceBuffer should not be updating on updateend!');
  907.     operation.p.resolve();
  908.     this.popFromQueue_(contentType);
  909.   }
  911.   /**
  912.    * Enqueue an operation and start it if appropriate.
  913.    *
  914.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  915.    * @param {function()} start
  916.    * @return {!Promise}
  917.    * @private
  918.    */
  919.   enqueueOperation_(contentType, start) {
  920.     this.destroyer_.ensureNotDestroyed();
  922.     const operation = {
  923.       start: start,
  924.       p: new shaka.util.PublicPromise(),
  925.     };
  926.     this.queues_[contentType].push(operation);
  928.     if (this.queues_[contentType].length == 1) {
  929.       this.startOperation_(contentType);
  930.     }
  931.     return operation.p;
  932.   }
  934.   /**
  935.    * Enqueue an operation which must block all other operations on all
  936.    * SourceBuffers.
  937.    *
  938.    * @param {function()} run
  939.    * @return {!Promise}
  940.    * @private
  941.    */
  942.   async enqueueBlockingOperation_(run) {
  943.     this.destroyer_.ensureNotDestroyed();
  945.     /** @type {!Array.<!shaka.util.PublicPromise>} */
  946.     const allWaiters = [];
  948.     // Enqueue a 'wait' operation onto each queue.
  949.     // This operation signals its readiness when it starts.
  950.     // When all wait operations are ready, the real operation takes place.
  951.     for (const contentType in this.sourceBuffers_) {
  952.       const ready = new shaka.util.PublicPromise();
  953.       const operation = {
  954.         start: () => ready.resolve(),
  955.         p: ready,
  956.       };
  958.       this.queues_[contentType].push(operation);
  959.       allWaiters.push(ready);
  961.       if (this.queues_[contentType].length == 1) {
  962.         operation.start();
  963.       }
  964.     }
  966.     // Return a Promise to the real operation, which waits to begin until
  967.     // there are no other in-progress operations on any SourceBuffers.
  968.     try {
  969.       await Promise.all(allWaiters);
  970.     } catch (error) {
  971.       // One of the waiters failed, which means we've been destroyed.
  972.       goog.asserts.assert(
  973.           this.destroyer_.destroyed(), 'Should be destroyed by now');
  974.       // We haven't popped from the queue.  Canceled waiters have been removed
  975.       // by destroy.  What's left now should just be resolved waiters.  In
  976.       // uncompiled mode, we will maintain good hygiene and make sure the
  977.       // assert at the end of destroy passes.  In compiled mode, the queues
  978.       // are wiped in destroy.
  979.       if (goog.DEBUG) {
  980.         for (const contentType in this.sourceBuffers_) {
  981.           if (this.queues_[contentType].length) {
  982.             goog.asserts.assert(
  983.                 this.queues_[contentType].length == 1,
  984.                 'Should be at most one item in queue!');
  985.             goog.asserts.assert(
  986.                 allWaiters.includes(this.queues_[contentType][0].p),
  987.                 'The item in queue should be one of our waiters!');
  988.             this.queues_[contentType].shift();
  989.           }
  990.         }
  991.       }
  992.       throw error;
  993.     }
  995.     if (goog.DEBUG) {
  996.       // If we did it correctly, nothing is updating.
  997.       for (const contentType in this.sourceBuffers_) {
  998.         goog.asserts.assert(
  999.             this.sourceBuffers_[contentType].updating == false,
  1000.             'SourceBuffers should not be updating after a blocking op!');
  1001.       }
  1002.     }
  1004.     // Run the real operation, which is synchronous.
  1005.     try {
  1006.       run();
  1007.     } catch (exception) {
  1008.       throw new shaka.util.Error(
  1009.           shaka.util.Error.Severity.CRITICAL,
  1010.           shaka.util.Error.Category.MEDIA,
  1011.           shaka.util.Error.Code.MEDIA_SOURCE_OPERATION_THREW,
  1012.           exception);
  1013.     } finally {
  1014.       // Unblock the queues.
  1015.       for (const contentType in this.sourceBuffers_) {
  1016.         this.popFromQueue_(contentType);
  1017.       }
  1018.     }
  1019.   }
  1021.   /**
  1022.    * Pop from the front of the queue and start a new operation.
  1023.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  1024.    * @private
  1025.    */
  1026.   popFromQueue_(contentType) {
  1027.     // Remove the in-progress operation, which is now complete.
  1028.     this.queues_[contentType].shift();
  1029.     this.startOperation_(contentType);
  1030.   }
  1032.   /**
  1033.    * Starts the next operation in the queue.
  1034.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  1035.    * @private
  1036.    */
  1037.   startOperation_(contentType) {
  1038.     // Retrieve the next operation, if any, from the queue and start it.
  1039.     const next = this.queues_[contentType][0];
  1040.     if (next) {
  1041.       try {
  1042.         next.start();
  1043.       } catch (exception) {
  1044.         if (exception.name == 'QuotaExceededError') {
  1045.           next.p.reject(new shaka.util.Error(
  1046.               shaka.util.Error.Severity.CRITICAL,
  1047.               shaka.util.Error.Category.MEDIA,
  1048.               shaka.util.Error.Code.QUOTA_EXCEEDED_ERROR,
  1049.               contentType));
  1050.         } else {
  1051.           next.p.reject(new shaka.util.Error(
  1052.               shaka.util.Error.Severity.CRITICAL,
  1053.               shaka.util.Error.Category.MEDIA,
  1054.               shaka.util.Error.Code.MEDIA_SOURCE_OPERATION_THREW,
  1055.               exception));
  1056.         }
  1057.         this.popFromQueue_(contentType);
  1058.       }
  1059.     }
  1060.   }
  1062.   /**
  1063.    * @return {!shaka.extern.TextDisplayer}
  1064.    */
  1065.   getTextDisplayer() {
  1066.     goog.asserts.assert(
  1067.         this.textDisplayer_,
  1068.         'TextDisplayer should only be null when this is destroyed');
  1070.     return this.textDisplayer_;
  1071.   }
  1073.   /**
  1074.    * @param {!shaka.extern.TextDisplayer} textDisplayer
  1075.    */
  1076.   setTextDisplayer(textDisplayer) {
  1077.     const oldTextDisplayer = this.textDisplayer_;
  1078.     this.textDisplayer_ = textDisplayer;
  1079.     if (oldTextDisplayer) {
  1080.       textDisplayer.setTextVisibility(oldTextDisplayer.isTextVisible());
  1081.       oldTextDisplayer.destroy();
  1082.     }
  1083.     if (this.textEngine_) {
  1084.       this.textEngine_.setDisplayer(textDisplayer);
  1085.     }
  1086.   }
  1088.   /**
  1089.    * Apply platform-specific transformations to this segment to work around
  1090.    * issues in the platform.
  1091.    *
  1092.    * @param {!BufferSource} segment
  1093.    * @param {?number} startTime
  1094.    * @param {shaka.util.ManifestParserUtils.ContentType} contentType
  1095.    * @return {!BufferSource}
  1096.    * @private
  1097.    */
  1098.   workAroundBrokenPlatforms_(segment, startTime, contentType) {
  1099.     const isInitSegment = startTime == null;
  1100.     const encryptionExpected = this.expectedEncryption_[contentType];
  1102.     // If:
  1103.     //   1. this is an init segment,
  1104.     //   2. and encryption is expected,
  1105.     //   3. and the platform requires encryption in all init segments,
  1106.     //   4. and the content is MP4 (mimeType == "video/mp4" or "audio/mp4"),
  1107.     // then insert fake encryption metadata for init segments that lack it.
  1108.     // The MP4 requirement is because we can currently only do this
  1109.     // transformation on MP4 containers.
  1110.     // See: https://github.com/shaka-project/shaka-player/issues/2759
  1111.     if (isInitSegment &&
  1112.         encryptionExpected &&
  1113.         shaka.util.Platform.requiresEncryptionInfoInAllInitSegments() &&
  1114.         shaka.util.MimeUtils.getContainerType(
  1115.             this.sourceBufferTypes_[contentType]) == 'mp4') {
  1116.       shaka.log.debug('Forcing fake encryption information in init segment.');
  1117.       segment = shaka.media.ContentWorkarounds.fakeEncryption(segment);
  1118.     }
  1120.     return segment;
  1121.   }
  1122. };
  1125. /**
  1126.  * Internal reference to window.URL.createObjectURL function to avoid
  1127.  * compatibility issues with other libraries and frameworks such as React
  1128.  * Native. For use in unit tests only, not meant for external use.
  1129.  *
  1130.  * @type {function(?):string}
  1131.  */
  1132. shaka.media.MediaSourceEngine.createObjectURL = window.URL.createObjectURL;
  1135. /**
  1136.  * @typedef {{
  1137.  *   start: function(),
  1138.  *   p: !shaka.util.PublicPromise
  1139.  * }}
  1140.  *
  1141.  * @summary An operation in queue.
  1142.  * @property {function()} start
  1143.  *   The function which starts the operation.
  1144.  * @property {!shaka.util.PublicPromise} p
  1145.  *   The PublicPromise which is associated with this operation.
  1146.  */
  1147. shaka.media.MediaSourceEngine.Operation;