Source: lib/abr/simple_abr_manager.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.abr.SimpleAbrManager');
  9. goog.require('goog.asserts');
  10. goog.require('shaka.abr.EwmaBandwidthEstimator');
  11. goog.require('shaka.log');
  12. goog.require('shaka.util.EventManager');
  13. goog.require('shaka.util.IReleasable');
  14. goog.require('shaka.util.StreamUtils');
  15. goog.require('shaka.util.Timer');
  17. goog.requireType('shaka.util.CmsdManager');
  20. /**
  21.  * @summary
  22.  * <p>
  23.  * This defines the default ABR manager for the Player.  An instance of this
  24.  * class is used when no ABR manager is given.
  25.  * </p>
  26.  * <p>
  27.  * The behavior of this class is to take throughput samples using
  28.  * segmentDownloaded to estimate the current network bandwidth.  Then it will
  29.  * use that to choose the streams that best fit the current bandwidth.  It will
  30.  * always pick the highest bandwidth variant it thinks can be played.
  31.  * </p>
  32.  * <p>
  33.  * After initial choices are made, this class will call switchCallback() when
  34.  * there is a better choice.  switchCallback() will not be called more than once
  35.  * per ({@link shaka.abr.SimpleAbrManager.SWITCH_INTERVAL_MS}).
  36.  * </p>
  37.  *
  38.  * @implements {shaka.extern.AbrManager}
  39.  * @implements {shaka.util.IReleasable}
  40.  * @export
  41.  */
  42. shaka.abr.SimpleAbrManager = class {
  43.   /** */
  44.   constructor() {
  45.     /** @private {?shaka.extern.AbrManager.SwitchCallback} */
  46.     this.switch_ = null;
  48.     /** @private {boolean} */
  49.     this.enabled_ = false;
  51.     /** @private {shaka.abr.EwmaBandwidthEstimator} */
  52.     this.bandwidthEstimator_ = new shaka.abr.EwmaBandwidthEstimator();
  54.     /** @private {!shaka.util.EventManager} */
  55.     this.eventManager_ = new shaka.util.EventManager();
  57.     // Some browsers implement the Network Information API, which allows
  58.     // retrieving information about a user's network connection. We listen
  59.     // to the change event to be able to make quick changes in case the type
  60.     // of connectivity changes.
  61.     if (navigator.connection && navigator.connection.addEventListener) {
  62.       this.eventManager_.listen(
  63.           /** @type {EventTarget} */(navigator.connection),
  64.           'change',
  65.           () => {
  66.             if (this.enabled_ && this.config_.useNetworkInformation) {
  67.               this.bandwidthEstimator_ = new shaka.abr.EwmaBandwidthEstimator();
  68.               if (this.config_) {
  69.                 this.bandwidthEstimator_.configure(this.config_.advanced);
  70.               }
  71.               const chosenVariant = this.chooseVariant();
  72.               if (chosenVariant && navigator.onLine) {
  73.                 this.switch_(chosenVariant, this.config_.clearBufferSwitch,
  74.                     this.config_.safeMarginSwitch);
  75.               }
  76.             }
  77.           });
  78.     }
  80.     /**
  81.      * A filtered list of Variants to choose from.
  82.      * @private {!Array<!shaka.extern.Variant>}
  83.      */
  84.     this.variants_ = [];
  86.     /** @private {number} */
  87.     this.playbackRate_ = 1;
  89.     /** @private {boolean} */
  90.     this.startupComplete_ = false;
  92.     /**
  93.      * The last wall-clock time, in milliseconds, when streams were chosen.
  94.      *
  95.      * @private {?number}
  96.      */
  97.     this.lastTimeChosenMs_ = null;
  99.     /** @private {?shaka.extern.AbrConfiguration} */
  100.     this.config_ = null;
  102.     /** @private {HTMLMediaElement} */
  103.     this.mediaElement_ = null;
  105.     /** @private {ResizeObserver} */
  106.     this.resizeObserver_ = null;
  108.     /** @private {shaka.util.Timer} */
  109.     this.resizeObserverTimer_ = new shaka.util.Timer(() => {
  110.       if (this.enabled_ && (this.config_.restrictToElementSize ||
  111.           this.config_.restrictToScreenSize)) {
  112.         const chosenVariant = this.chooseVariant();
  113.         if (chosenVariant) {
  114.           this.switch_(chosenVariant, this.config_.clearBufferSwitch,
  115.               this.config_.safeMarginSwitch);
  116.         }
  117.       }
  118.     });
  120.     /** @private {Window} */
  121.     this.windowToCheck_ = window;
  123.     if ('documentPictureInPicture' in window) {
  124.       this.eventManager_.listen(
  125.           window.documentPictureInPicture, 'enter', () => {
  126.             this.windowToCheck_ = window.documentPictureInPicture.window;
  127.             if (this.resizeObserverTimer_) {
  128.               this.resizeObserverTimer_.tickNow();
  129.             }
  130.             this.eventManager_.listenOnce(
  131.                 this.windowToCheck_, 'pagehide', () => {
  132.                   this.windowToCheck_ = window;
  133.                   if (this.resizeObserverTimer_) {
  134.                     this.resizeObserverTimer_.tickNow();
  135.                   }
  136.                 });
  137.           });
  138.     }
  140.     /** @private {PictureInPictureWindow} */
  141.     this.pictureInPictureWindow_ = null;
  143.     /** @private {?shaka.util.CmsdManager} */
  144.     this.cmsdManager_ = null;
  145.   }
  148.   /**
  149.    * @override
  150.    * @export
  151.    */
  152.   stop() {
  153.     this.switch_ = null;
  154.     this.enabled_ = false;
  155.     this.variants_ = [];
  156.     this.playbackRate_ = 1;
  157.     this.lastTimeChosenMs_ = null;
  158.     this.mediaElement_ = null;
  160.     if (this.resizeObserver_) {
  161.       this.resizeObserver_.disconnect();
  162.       this.resizeObserver_ = null;
  163.     }
  165.     this.resizeObserverTimer_.stop();
  167.     this.pictureInPictureWindow_ = null;
  169.     this.cmsdManager_ = null;
  171.     // Don't reset |startupComplete_|: if we've left the startup interval, we
  172.     // can start using bandwidth estimates right away after init() is called.
  173.   }
  175.   /**
  176.    * @override
  177.    * @export
  178.    */
  179.   release() {
  180.     // stop() should already have been called for unload
  181.     this.eventManager_.release();
  182.     this.resizeObserverTimer_ = null;
  183.   }
  186.   /**
  187.    * @override
  188.    * @export
  189.    */
  190.   init(switchCallback) {
  191.     this.switch_ = switchCallback;
  192.   }
  195.   /**
  196.    * @return {shaka.extern.Variant}
  197.    * @override
  198.    * @export
  199.    */
  200.   chooseVariant() {
  201.     let maxHeight = Infinity;
  202.     let maxWidth = Infinity;
  204.     if (this.config_.restrictToScreenSize) {
  205.       const devicePixelRatio = this.config_.ignoreDevicePixelRatio ?
  206.           1 : this.windowToCheck_.devicePixelRatio;
  207.       maxHeight = this.windowToCheck_.screen.height * devicePixelRatio;
  208.       maxWidth = this.windowToCheck_.screen.width * devicePixelRatio;
  209.     }
  211.     if (this.resizeObserver_ && this.config_.restrictToElementSize) {
  212.       const devicePixelRatio = this.config_.ignoreDevicePixelRatio ?
  213.           1 : this.windowToCheck_.devicePixelRatio;
  214.       let height = this.mediaElement_.clientHeight;
  215.       let width = this.mediaElement_.clientWidth;
  216.       if (this.pictureInPictureWindow_ && document.pictureInPictureElement &&
  217.           document.pictureInPictureElement == this.mediaElement_) {
  218.         height = this.pictureInPictureWindow_.height;
  219.         width = this.pictureInPictureWindow_.width;
  220.       }
  221.       maxHeight = Math.min(maxHeight, height * devicePixelRatio);
  222.       maxWidth = Math.min(maxWidth, width * devicePixelRatio);
  223.     }
  225.     let normalVariants = this.variants_.filter((variant) => {
  226.       return variant && !shaka.util.StreamUtils.isFastSwitching(variant);
  227.     });
  228.     if (!normalVariants.length) {
  229.       normalVariants = this.variants_;
  230.     }
  232.     let variants = normalVariants;
  233.     if (normalVariants.length != this.variants_.length) {
  234.       variants = this.variants_.filter((variant) => {
  235.         return variant && shaka.util.StreamUtils.isFastSwitching(variant);
  236.       });
  237.     }
  239.     // Get sorted Variants.
  240.     let sortedVariants = this.filterAndSortVariants_(
  241.         this.config_.restrictions, variants,
  242.         /* maxHeight= */ Infinity, /* maxWidth= */ Infinity);
  244.     if (maxHeight != Infinity || maxWidth != Infinity) {
  245.       const resolutions = this.getResolutionList_(sortedVariants);
  246.       for (const resolution of resolutions) {
  247.         if (resolution.height >= maxHeight && resolution.width >= maxWidth) {
  248.           maxHeight = resolution.height;
  249.           maxWidth = resolution.width;
  250.           break;
  251.         }
  252.       }
  254.       sortedVariants = this.filterAndSortVariants_(
  255.           this.config_.restrictions, variants, maxHeight, maxWidth);
  256.     }
  258.     const currentBandwidth = this.getBandwidthEstimate();
  260.     if (variants.length && !sortedVariants.length) {
  261.       // If we couldn't meet the ABR restrictions, we should still play
  262.       // something.
  263.       // These restrictions are not "hard" restrictions in the way that
  264.       // top-level or DRM-based restrictions are.  Sort the variants without
  265.       // restrictions and keep just the first (lowest-bandwidth) one.
  266.       shaka.log.warning('No variants met the ABR restrictions. ' +
  267.                         'Choosing a variant by lowest bandwidth.');
  268.       sortedVariants = this.filterAndSortVariants_(
  269.           /* restrictions= */ null, variants,
  270.           /* maxHeight= */ Infinity, /* maxWidth= */ Infinity);
  271.       sortedVariants = [sortedVariants[0]];
  272.     }
  274.     // Start by assuming that we will use the first Stream.
  275.     let chosen = sortedVariants[0] || null;
  277.     for (let i = 0; i < sortedVariants.length; i++) {
  278.       const item = sortedVariants[i];
  279.       const playbackRate =
  280.           !isNaN(this.playbackRate_) ? Math.abs(this.playbackRate_) : 1;
  281.       const itemBandwidth = playbackRate * item.bandwidth;
  282.       const minBandwidth =
  283.           itemBandwidth / this.config_.bandwidthDowngradeTarget;
  284.       let next = {bandwidth: Infinity};
  285.       for (let j = i + 1; j < sortedVariants.length; j++) {
  286.         if (item.bandwidth != sortedVariants[j].bandwidth) {
  287.           next = sortedVariants[j];
  288.           break;
  289.         }
  290.       }
  291.       const nextBandwidth = playbackRate * next.bandwidth;
  292.       const maxBandwidth = nextBandwidth / this.config_.bandwidthUpgradeTarget;
  293.       shaka.log.v2('Bandwidth ranges:',
  294.           (itemBandwidth / 1e6).toFixed(3),
  295.           (minBandwidth / 1e6).toFixed(3),
  296.           (maxBandwidth / 1e6).toFixed(3));
  298.       if (currentBandwidth >= minBandwidth &&
  299.           currentBandwidth <= maxBandwidth &&
  300.           (chosen.bandwidth != item.bandwidth ||
  301.           this.isSameBandwidthAndHigherResolution_(chosen, item))) {
  302.         chosen = item;
  303.       }
  304.     }
  306.     this.lastTimeChosenMs_ = Date.now();
  307.     return chosen;
  308.   }
  311.   /**
  312.    * @override
  313.    * @export
  314.    */
  315.   enable() {
  316.     this.enabled_ = true;
  317.   }
  320.   /**
  321.    * @override
  322.    * @export
  323.    */
  324.   disable() {
  325.     this.enabled_ = false;
  326.   }
  329.   /**
  330.    * @param {number} deltaTimeMs The duration, in milliseconds, that the request
  331.    *     took to complete.
  332.    * @param {number} numBytes The total number of bytes transferred.
  333.    * @param {boolean} allowSwitch Indicate if the segment is allowed to switch
  334.    *     to another stream.
  335.    * @param {shaka.extern.Request=} request
  336.    *     A reference to the request
  337.    * @override
  338.    * @export
  339.    */
  340.   segmentDownloaded(deltaTimeMs, numBytes, allowSwitch, request) {
  341.     if (deltaTimeMs < this.config_.cacheLoadThreshold) {
  342.       // The time indicates that it could be a cache response, so we should
  343.       // ignore this value.
  344.       return;
  345.     }
  346.     shaka.log.v2('Segment downloaded:',
  347.         'contentType=' + (request && request.contentType),
  348.         'deltaTimeMs=' + deltaTimeMs,
  349.         'numBytes=' + numBytes,
  350.         'lastTimeChosenMs=' + this.lastTimeChosenMs_,
  351.         'enabled=' + this.enabled_);
  352.     goog.asserts.assert(deltaTimeMs >= 0, 'expected a non-negative duration');
  353.     this.bandwidthEstimator_.sample(deltaTimeMs, numBytes);
  355.     if (allowSwitch && (this.lastTimeChosenMs_ != null) && this.enabled_) {
  356.       this.suggestStreams_();
  357.     }
  358.   }
  361.   /**
  362.    * @override
  363.    * @export
  364.    */
  365.   trySuggestStreams() {
  366.     if ((this.lastTimeChosenMs_ != null) && this.enabled_) {
  367.       this.suggestStreams_();
  368.     }
  369.   }
  372.   /**
  373.    * @override
  374.    * @export
  375.    */
  376.   getBandwidthEstimate() {
  377.     const defaultBandwidthEstimate = this.getDefaultBandwidth_();
  378.     if (navigator.connection && navigator.connection.downlink &&
  379.         this.config_.useNetworkInformation &&
  380.         this.config_.preferNetworkInformationBandwidth) {
  381.       return defaultBandwidthEstimate;
  382.     }
  383.     const bandwidthEstimate = this.bandwidthEstimator_.getBandwidthEstimate(
  384.         defaultBandwidthEstimate);
  385.     if (this.cmsdManager_) {
  386.       return this.cmsdManager_.getBandwidthEstimate(bandwidthEstimate);
  387.     }
  388.     return bandwidthEstimate;
  389.   }
  392.   /**
  393.    * @override
  394.    * @export
  395.    */
  396.   setVariants(variants) {
  397.     this.variants_ = variants;
  398.   }
  401.   /**
  402.    * @override
  403.    * @export
  404.    */
  405.   playbackRateChanged(rate) {
  406.     this.playbackRate_ = rate;
  407.   }
  410.   /**
  411.    * @override
  412.    * @export
  413.    */
  414.   setMediaElement(mediaElement) {
  415.     this.mediaElement_ = mediaElement;
  416.     if (this.resizeObserver_) {
  417.       this.resizeObserver_.disconnect();
  418.       this.resizeObserver_ = null;
  419.     }
  420.     const onResize = () => {
  421.       const SimpleAbrManager = shaka.abr.SimpleAbrManager;
  422.       // Batch up resize changes before checking them.
  423.       this.resizeObserverTimer_.tickAfter(
  424.           /* seconds= */ SimpleAbrManager.RESIZE_OBSERVER_BATCH_TIME);
  425.     };
  426.     if (this.mediaElement_ && 'ResizeObserver' in window) {
  427.       this.resizeObserver_ = new ResizeObserver(onResize);
  428.       this.resizeObserver_.observe(this.mediaElement_);
  429.     }
  431.     this.eventManager_.listen(mediaElement, 'enterpictureinpicture', (e) => {
  432.       const event = /** @type {PictureInPictureEvent} */(e);
  433.       if (event.pictureInPictureWindow) {
  434.         this.pictureInPictureWindow_ = event.pictureInPictureWindow;
  435.         this.eventManager_.listen(
  436.             this.pictureInPictureWindow_, 'resize', onResize);
  437.       }
  438.     });
  439.     this.eventManager_.listen(mediaElement, 'leavepictureinpicture', () => {
  440.       if (this.pictureInPictureWindow_) {
  441.         this.eventManager_.unlisten(
  442.             this.pictureInPictureWindow_, 'resize', onResize);
  443.       }
  444.       this.pictureInPictureWindow_ = null;
  445.     });
  446.   }
  449.   /**
  450.    * @override
  451.    * @export
  452.    */
  453.   setCmsdManager(cmsdManager) {
  454.     this.cmsdManager_ = cmsdManager;
  455.   }
  458.   /**
  459.    * @override
  460.    * @export
  461.    */
  462.   configure(config) {
  463.     this.config_ = config;
  464.     if (this.bandwidthEstimator_ && this.config_) {
  465.       this.bandwidthEstimator_.configure(this.config_.advanced);
  466.     }
  467.   }
  470.   /**
  471.    * Calls switch_() with the variant chosen by chooseVariant().
  472.    *
  473.    * @private
  474.    */
  475.   suggestStreams_() {
  476.     shaka.log.v2('Suggesting Streams...');
  477.     goog.asserts.assert(this.lastTimeChosenMs_ != null,
  478.         'lastTimeChosenMs_ should not be null');
  480.     if (!this.startupComplete_) {
  481.       // Check if we've got enough data yet.
  482.       if (!this.bandwidthEstimator_.hasGoodEstimate()) {
  483.         shaka.log.v2('Still waiting for a good estimate...');
  484.         return;
  485.       }
  486.       this.startupComplete_ = true;
  488.       this.lastTimeChosenMs_ -=
  489.           (this.config_.switchInterval - this.config_.minTimeToSwitch) * 1000;
  490.     }
  492.     // Check if we've left the switch interval.
  493.     const now = Date.now();
  494.     const delta = now - this.lastTimeChosenMs_;
  495.     if (delta < this.config_.switchInterval * 1000) {
  496.       shaka.log.v2('Still within switch interval...');
  497.       return;
  498.     }
  500.     const chosenVariant = this.chooseVariant();
  501.     const bandwidthEstimate = this.getBandwidthEstimate();
  502.     const currentBandwidthKbps = Math.round(bandwidthEstimate / 1000.0);
  504.     if (chosenVariant) {
  505.       shaka.log.debug(
  506.           'Calling switch_(), bandwidth=' + currentBandwidthKbps + ' kbps');
  507.       // If any of these chosen streams are already chosen, Player will filter
  508.       // them out before passing the choices on to StreamingEngine.
  509.       this.switch_(chosenVariant, this.config_.clearBufferSwitch,
  510.           this.config_.safeMarginSwitch);
  511.     }
  512.   }
  515.   /**
  516.    * @private
  517.    */
  518.   getDefaultBandwidth_() {
  519.     let defaultBandwidthEstimate = this.config_.defaultBandwidthEstimate;
  521.     // Some browsers implement the Network Information API, which allows
  522.     // retrieving information about a user's network connection.  Tizen 3 has
  523.     // NetworkInformation, but not the downlink attribute.
  524.     if (navigator.connection && navigator.connection.downlink &&
  525.         this.config_.useNetworkInformation) {
  526.       // If it's available, get the bandwidth estimate from the browser (in
  527.       // megabits per second) and use it as defaultBandwidthEstimate.
  528.       defaultBandwidthEstimate = navigator.connection.downlink * 1e6;
  529.     }
  530.     return defaultBandwidthEstimate;
  531.   }
  534.   /**
  535.    * @param {?shaka.extern.Restrictions} restrictions
  536.    * @param {!Array<shaka.extern.Variant>} variants
  537.    * @param {!number} maxHeight
  538.    * @param {!number} maxWidth
  539.    * @return {!Array<shaka.extern.Variant>} variants filtered according to
  540.    *   |restrictions| and sorted in ascending order of bandwidth.
  541.    * @private
  542.    */
  543.   filterAndSortVariants_(restrictions, variants, maxHeight, maxWidth) {
  544.     if (this.cmsdManager_) {
  545.       const maxBitrate = this.cmsdManager_.getMaxBitrate();
  546.       if (maxBitrate) {
  547.         variants = variants.filter((variant) => {
  548.           if (!variant.bandwidth || !maxBitrate) {
  549.             return true;
  550.           }
  551.           return variant.bandwidth <= maxBitrate;
  552.         });
  553.       }
  554.     }
  556.     if (restrictions) {
  557.       variants = variants.filter((variant) => {
  558.         // This was already checked in another scope, but the compiler doesn't
  559.         // seem to understand that.
  560.         goog.asserts.assert(restrictions, 'Restrictions should exist!');
  562.         return shaka.util.StreamUtils.meetsRestrictions(
  563.             variant, restrictions,
  564.             /* maxHwRes= */ {width: maxWidth, height: maxHeight});
  565.       });
  566.     }
  568.     return variants.sort((v1, v2) => {
  569.       return v1.bandwidth - v2.bandwidth;
  570.     });
  571.   }
  573.   /**
  574.    * @param {!Array<shaka.extern.Variant>} variants
  575.    * @return {!Array<{height: number, width: number}>}
  576.    * @private
  577.    */
  578.   getResolutionList_(variants) {
  579.     const resolutions = [];
  580.     for (const variant of variants) {
  581.       const video = variant.video;
  582.       if (!video || !video.height || !video.width) {
  583.         continue;
  584.       }
  585.       resolutions.push({
  586.         height: video.height,
  587.         width: video.width,
  588.       });
  589.     }
  591.     return resolutions.sort((v1, v2) => {
  592.       return v1.width - v2.width;
  593.     });
  594.   }
  596.   /**
  597.    * @param {shaka.extern.Variant} chosenVariant
  598.    * @param {shaka.extern.Variant} newVariant
  599.    * @return {boolean}
  600.    * @private
  601.    */
  602.   isSameBandwidthAndHigherResolution_(chosenVariant, newVariant) {
  603.     if (chosenVariant.bandwidth != newVariant.bandwidth) {
  604.       return false;
  605.     }
  606.     if (!chosenVariant.video || !newVariant.video) {
  607.       return false;
  608.     }
  609.     return chosenVariant.video.width < newVariant.video.width ||
  610.         chosenVariant.video.height < newVariant.video.height;
  611.   }
  612. };
  615. /**
  616.  * The amount of time, in seconds, we wait to batch up rapid resize changes.
  617.  * This allows us to avoid multiple resize events in most cases.
  618.  * @type {number}
  619.  */
  620. shaka.abr.SimpleAbrManager.RESIZE_OBSERVER_BATCH_TIME = 1;