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.         const chosenVariant = this.chooseVariant();
  112.         if (chosenVariant) {
  113.           this.switch_(chosenVariant, this.config_.clearBufferSwitch,
  114.               this.config_.safeMarginSwitch);
  115.         }
  116.       }
  117.     });
  119.     /** @private {?shaka.util.CmsdManager} */
  120.     this.cmsdManager_ = null;
  121.   }
  124.   /**
  125.    * @override
  126.    * @export
  127.    */
  128.   stop() {
  129.     this.switch_ = null;
  130.     this.enabled_ = false;
  131.     this.variants_ = [];
  132.     this.playbackRate_ = 1;
  133.     this.lastTimeChosenMs_ = null;
  134.     this.mediaElement_ = null;
  136.     if (this.resizeObserver_) {
  137.       this.resizeObserver_.disconnect();
  138.       this.resizeObserver_ = null;
  139.     }
  141.     this.resizeObserverTimer_.stop();
  143.     this.cmsdManager_ = null;
  145.     // Don't reset |startupComplete_|: if we've left the startup interval, we
  146.     // can start using bandwidth estimates right away after init() is called.
  147.   }
  149.   /**
  150.    * @override
  151.    * @export
  152.    */
  153.   release() {
  154.     // stop() should already have been called for unload
  155.     this.eventManager_.release();
  156.     this.resizeObserverTimer_ = null;
  157.   }
  160.   /**
  161.    * @override
  162.    * @export
  163.    */
  164.   init(switchCallback) {
  165.     this.switch_ = switchCallback;
  166.   }
  169.   /**
  170.    * @return {shaka.extern.Variant}
  171.    * @override
  172.    * @export
  173.    */
  174.   chooseVariant() {
  175.     let maxHeight = Infinity;
  176.     let maxWidth = Infinity;
  178.     if (this.config_.restrictToScreenSize) {
  179.       const devicePixelRatio =
  180.           this.config_.ignoreDevicePixelRatio ? 1 : window.devicePixelRatio;
  181.       maxHeight = window.screen.height * devicePixelRatio;
  182.       maxWidth = window.screen.width * devicePixelRatio;
  183.     }
  185.     if (this.resizeObserver_ && this.config_.restrictToElementSize) {
  186.       const devicePixelRatio =
  187.           this.config_.ignoreDevicePixelRatio ? 1 : window.devicePixelRatio;
  188.       maxHeight = Math.min(
  189.           maxHeight, this.mediaElement_.clientHeight * devicePixelRatio);
  190.       maxWidth = Math.min(
  191.           maxWidth, this.mediaElement_.clientWidth * devicePixelRatio);
  192.     }
  194.     let normalVariants = this.variants_.filter((variant) => {
  195.       return variant && !shaka.util.StreamUtils.isFastSwitching(variant);
  196.     });
  197.     if (!normalVariants.length) {
  198.       normalVariants = this.variants_;
  199.     }
  201.     let variants = normalVariants;
  202.     if (normalVariants.length != this.variants_.length) {
  203.       variants = this.variants_.filter((variant) => {
  204.         return variant && shaka.util.StreamUtils.isFastSwitching(variant);
  205.       });
  206.     }
  208.     // Get sorted Variants.
  209.     let sortedVariants = this.filterAndSortVariants_(
  210.         this.config_.restrictions, variants,
  211.         /* maxHeight= */ Infinity, /* maxWidth= */ Infinity);
  213.     if (maxHeight != Infinity || maxWidth != Infinity) {
  214.       const resolutions = this.getResolutionList_(sortedVariants);
  215.       for (const resolution of resolutions) {
  216.         if (resolution.height >= maxHeight && resolution.width >= maxWidth) {
  217.           maxHeight = resolution.height;
  218.           maxWidth = resolution.width;
  219.           break;
  220.         }
  221.       }
  223.       sortedVariants = this.filterAndSortVariants_(
  224.           this.config_.restrictions, variants, maxHeight, maxWidth);
  225.     }
  227.     const currentBandwidth = this.getBandwidthEstimate();
  229.     if (variants.length && !sortedVariants.length) {
  230.       // If we couldn't meet the ABR restrictions, we should still play
  231.       // something.
  232.       // These restrictions are not "hard" restrictions in the way that
  233.       // top-level or DRM-based restrictions are.  Sort the variants without
  234.       // restrictions and keep just the first (lowest-bandwidth) one.
  235.       shaka.log.warning('No variants met the ABR restrictions. ' +
  236.                         'Choosing a variant by lowest bandwidth.');
  237.       sortedVariants = this.filterAndSortVariants_(
  238.           /* restrictions= */ null, variants,
  239.           /* maxHeight= */ Infinity, /* maxWidth= */ Infinity);
  240.       sortedVariants = [sortedVariants[0]];
  241.     }
  243.     // Start by assuming that we will use the first Stream.
  244.     let chosen = sortedVariants[0] || null;
  246.     for (let i = 0; i < sortedVariants.length; i++) {
  247.       const item = sortedVariants[i];
  248.       const playbackRate =
  249.           !isNaN(this.playbackRate_) ? Math.abs(this.playbackRate_) : 1;
  250.       const itemBandwidth = playbackRate * item.bandwidth;
  251.       const minBandwidth =
  252.           itemBandwidth / this.config_.bandwidthDowngradeTarget;
  253.       let next = {bandwidth: Infinity};
  254.       for (let j = i + 1; j < sortedVariants.length; j++) {
  255.         if (item.bandwidth != sortedVariants[j].bandwidth) {
  256.           next = sortedVariants[j];
  257.           break;
  258.         }
  259.       }
  260.       const nextBandwidth = playbackRate * next.bandwidth;
  261.       const maxBandwidth = nextBandwidth / this.config_.bandwidthUpgradeTarget;
  262.       shaka.log.v2('Bandwidth ranges:',
  263.           (itemBandwidth / 1e6).toFixed(3),
  264.           (minBandwidth / 1e6).toFixed(3),
  265.           (maxBandwidth / 1e6).toFixed(3));
  267.       if (currentBandwidth >= minBandwidth &&
  268.           currentBandwidth <= maxBandwidth &&
  269.           (chosen.bandwidth != item.bandwidth ||
  270.           this.isSameBandwidthAndHigherResolution_(chosen, item))) {
  271.         chosen = item;
  272.       }
  273.     }
  275.     this.lastTimeChosenMs_ = Date.now();
  276.     return chosen;
  277.   }
  280.   /**
  281.    * @override
  282.    * @export
  283.    */
  284.   enable() {
  285.     this.enabled_ = true;
  286.   }
  289.   /**
  290.    * @override
  291.    * @export
  292.    */
  293.   disable() {
  294.     this.enabled_ = false;
  295.   }
  298.   /**
  299.    * @param {number} deltaTimeMs The duration, in milliseconds, that the request
  300.    *     took to complete.
  301.    * @param {number} numBytes The total number of bytes transferred.
  302.    * @param {boolean} allowSwitch Indicate if the segment is allowed to switch
  303.    *     to another stream.
  304.    * @param {shaka.extern.Request=} request
  305.    *     A reference to the request
  306.    * @override
  307.    * @export
  308.    */
  309.   segmentDownloaded(deltaTimeMs, numBytes, allowSwitch, request) {
  310.     if (deltaTimeMs < this.config_.cacheLoadThreshold) {
  311.       // The time indicates that it could be a cache response, so we should
  312.       // ignore this value.
  313.       return;
  314.     }
  315.     shaka.log.v2('Segment downloaded:',
  316.         'contentType=' + (request && request.contentType),
  317.         'deltaTimeMs=' + deltaTimeMs,
  318.         'numBytes=' + numBytes,
  319.         'lastTimeChosenMs=' + this.lastTimeChosenMs_,
  320.         'enabled=' + this.enabled_);
  321.     goog.asserts.assert(deltaTimeMs >= 0, 'expected a non-negative duration');
  322.     this.bandwidthEstimator_.sample(deltaTimeMs, numBytes);
  324.     if (allowSwitch && (this.lastTimeChosenMs_ != null) && this.enabled_) {
  325.       this.suggestStreams_();
  326.     }
  327.   }
  330.   /**
  331.    * @override
  332.    * @export
  333.    */
  334.   trySuggestStreams() {
  335.     if ((this.lastTimeChosenMs_ != null) && this.enabled_) {
  336.       this.suggestStreams_();
  337.     }
  338.   }
  341.   /**
  342.    * @override
  343.    * @export
  344.    */
  345.   getBandwidthEstimate() {
  346.     const defaultBandwidthEstimate = this.getDefaultBandwidth_();
  347.     if (navigator.connection && navigator.connection.downlink &&
  348.         this.config_.useNetworkInformation &&
  349.         this.config_.preferNetworkInformationBandwidth) {
  350.       return defaultBandwidthEstimate;
  351.     }
  352.     const bandwidthEstimate = this.bandwidthEstimator_.getBandwidthEstimate(
  353.         defaultBandwidthEstimate);
  354.     if (this.cmsdManager_) {
  355.       return this.cmsdManager_.getBandwidthEstimate(bandwidthEstimate);
  356.     }
  357.     return bandwidthEstimate;
  358.   }
  361.   /**
  362.    * @override
  363.    * @export
  364.    */
  365.   setVariants(variants) {
  366.     this.variants_ = variants;
  367.   }
  370.   /**
  371.    * @override
  372.    * @export
  373.    */
  374.   playbackRateChanged(rate) {
  375.     this.playbackRate_ = rate;
  376.   }
  379.   /**
  380.    * @override
  381.    * @export
  382.    */
  383.   setMediaElement(mediaElement) {
  384.     this.mediaElement_ = mediaElement;
  385.     if (this.resizeObserver_) {
  386.       this.resizeObserver_.disconnect();
  387.       this.resizeObserver_ = null;
  388.     }
  389.     if (this.mediaElement_ && 'ResizeObserver' in window) {
  390.       this.resizeObserver_ = new ResizeObserver(() => {
  391.         const SimpleAbrManager = shaka.abr.SimpleAbrManager;
  392.         // Batch up resize changes before checking them.
  393.         this.resizeObserverTimer_.tickAfter(
  394.             /* seconds= */ SimpleAbrManager.RESIZE_OBSERVER_BATCH_TIME);
  395.       });
  396.       this.resizeObserver_.observe(this.mediaElement_);
  397.     }
  398.   }
  401.   /**
  402.    * @override
  403.    * @export
  404.    */
  405.   setCmsdManager(cmsdManager) {
  406.     this.cmsdManager_ = cmsdManager;
  407.   }
  410.   /**
  411.    * @override
  412.    * @export
  413.    */
  414.   configure(config) {
  415.     this.config_ = config;
  416.     if (this.bandwidthEstimator_ && this.config_) {
  417.       this.bandwidthEstimator_.configure(this.config_.advanced);
  418.     }
  419.   }
  422.   /**
  423.    * Calls switch_() with the variant chosen by chooseVariant().
  424.    *
  425.    * @private
  426.    */
  427.   suggestStreams_() {
  428.     shaka.log.v2('Suggesting Streams...');
  429.     goog.asserts.assert(this.lastTimeChosenMs_ != null,
  430.         'lastTimeChosenMs_ should not be null');
  432.     if (!this.startupComplete_) {
  433.       // Check if we've got enough data yet.
  434.       if (!this.bandwidthEstimator_.hasGoodEstimate()) {
  435.         shaka.log.v2('Still waiting for a good estimate...');
  436.         return;
  437.       }
  438.       this.startupComplete_ = true;
  440.       this.lastTimeChosenMs_ -=
  441.           (this.config_.switchInterval - this.config_.minTimeToSwitch) * 1000;
  442.     }
  444.     // Check if we've left the switch interval.
  445.     const now = Date.now();
  446.     const delta = now - this.lastTimeChosenMs_;
  447.     if (delta < this.config_.switchInterval * 1000) {
  448.       shaka.log.v2('Still within switch interval...');
  449.       return;
  450.     }
  452.     const chosenVariant = this.chooseVariant();
  453.     const bandwidthEstimate = this.getBandwidthEstimate();
  454.     const currentBandwidthKbps = Math.round(bandwidthEstimate / 1000.0);
  456.     if (chosenVariant) {
  457.       shaka.log.debug(
  458.           'Calling switch_(), bandwidth=' + currentBandwidthKbps + ' kbps');
  459.       // If any of these chosen streams are already chosen, Player will filter
  460.       // them out before passing the choices on to StreamingEngine.
  461.       this.switch_(chosenVariant, this.config_.clearBufferSwitch,
  462.           this.config_.safeMarginSwitch);
  463.     }
  464.   }
  467.   /**
  468.    * @private
  469.    */
  470.   getDefaultBandwidth_() {
  471.     let defaultBandwidthEstimate = this.config_.defaultBandwidthEstimate;
  473.     // Some browsers implement the Network Information API, which allows
  474.     // retrieving information about a user's network connection.  Tizen 3 has
  475.     // NetworkInformation, but not the downlink attribute.
  476.     if (navigator.connection && navigator.connection.downlink &&
  477.         this.config_.useNetworkInformation) {
  478.       // If it's available, get the bandwidth estimate from the browser (in
  479.       // megabits per second) and use it as defaultBandwidthEstimate.
  480.       defaultBandwidthEstimate = navigator.connection.downlink * 1e6;
  481.     }
  482.     return defaultBandwidthEstimate;
  483.   }
  486.   /**
  487.    * @param {?shaka.extern.Restrictions} restrictions
  488.    * @param {!Array.<shaka.extern.Variant>} variants
  489.    * @param {!number} maxHeight
  490.    * @param {!number} maxWidth
  491.    * @return {!Array.<shaka.extern.Variant>} variants filtered according to
  492.    *   |restrictions| and sorted in ascending order of bandwidth.
  493.    * @private
  494.    */
  495.   filterAndSortVariants_(restrictions, variants, maxHeight, maxWidth) {
  496.     if (this.cmsdManager_) {
  497.       const maxBitrate = this.cmsdManager_.getMaxBitrate();
  498.       if (maxBitrate) {
  499.         variants = variants.filter((variant) => {
  500.           if (!variant.bandwidth || !maxBitrate) {
  501.             return true;
  502.           }
  503.           return variant.bandwidth <= maxBitrate;
  504.         });
  505.       }
  506.     }
  508.     if (restrictions) {
  509.       variants = variants.filter((variant) => {
  510.         // This was already checked in another scope, but the compiler doesn't
  511.         // seem to understand that.
  512.         goog.asserts.assert(restrictions, 'Restrictions should exist!');
  514.         return shaka.util.StreamUtils.meetsRestrictions(
  515.             variant, restrictions,
  516.             /* maxHwRes= */ {width: maxWidth, height: maxHeight});
  517.       });
  518.     }
  520.     return variants.sort((v1, v2) => {
  521.       return v1.bandwidth - v2.bandwidth;
  522.     });
  523.   }
  525.   /**
  526.    * @param {!Array.<shaka.extern.Variant>} variants
  527.    * @return {!Array.<{height: number, width: number}>}
  528.    * @private
  529.    */
  530.   getResolutionList_(variants) {
  531.     const resolutions = [];
  532.     for (const variant of variants) {
  533.       const video = variant.video;
  534.       if (!video || !video.height || !video.width) {
  535.         continue;
  536.       }
  537.       resolutions.push({
  538.         height: video.height,
  539.         width: video.width,
  540.       });
  541.     }
  543.     return resolutions.sort((v1, v2) => {
  544.       return v1.width - v2.width;
  545.     });
  546.   }
  548.   /**
  549.    * @param {shaka.extern.Variant} chosenVariant
  550.    * @param {shaka.extern.Variant} newVariant
  551.    * @return {boolean}
  552.    * @private
  553.    */
  554.   isSameBandwidthAndHigherResolution_(chosenVariant, newVariant) {
  555.     if (chosenVariant.bandwidth != newVariant.bandwidth) {
  556.       return false;
  557.     }
  558.     if (!chosenVariant.video || !newVariant.video) {
  559.       return false;
  560.     }
  561.     return chosenVariant.video.width < newVariant.video.width ||
  562.         chosenVariant.video.height < newVariant.video.height;
  563.   }
  564. };
  567. /**
  568.  * The amount of time, in seconds, we wait to batch up rapid resize changes.
  569.  * This allows us to avoid multiple resize events in most cases.
  570.  * @type {number}
  571.  */
  572. shaka.abr.SimpleAbrManager.RESIZE_OBSERVER_BATCH_TIME = 1;