Source: lib/transmuxer/transmuxer_engine.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.transmuxer.TransmuxerEngine');
  9. goog.require('shaka.util.IDestroyable');
  12. // TODO: revisit this when Closure Compiler supports partially-exported classes.
  13. /**
  14.  * @summary Manages transmuxer plugins.
  15.  * @implements {shaka.util.IDestroyable}
  16.  * @export
  17.  */
  18. shaka.transmuxer.TransmuxerEngine = class {
  19.   // TODO: revisit this when the compiler supports partially-exported classes.
  20.   /**
  21.    * @override
  22.    * @export
  23.    */
  24.   destroy() {}
  26.   /**
  27.    * @param {string} mimeType
  28.    * @param {!shaka.extern.TransmuxerPlugin} plugin
  29.    * @param {number} priority
  30.    * @export
  31.    */
  32.   static registerTransmuxer(mimeType, plugin, priority) {
  33.     const TransmuxerEngine = shaka.transmuxer.TransmuxerEngine;
  34.     const normalizedMimetype = TransmuxerEngine.normalizeMimeType_(mimeType);
  35.     const key = normalizedMimetype + '-' + priority;
  36.     TransmuxerEngine.transmuxerMap_[key] = {
  37.       priority: priority,
  38.       plugin: plugin,
  39.     };
  40.   }
  42.   /**
  43.    * @param {string} mimeType
  44.    * @param {number} priority
  45.    * @export
  46.    */
  47.   static unregisterTransmuxer(mimeType, priority) {
  48.     const TransmuxerEngine = shaka.transmuxer.TransmuxerEngine;
  49.     const normalizedMimetype = TransmuxerEngine.normalizeMimeType_(mimeType);
  50.     const key = normalizedMimetype + '-' + priority;
  51.     delete TransmuxerEngine.transmuxerMap_[key];
  52.   }
  54.   /**
  55.    * @param {string} mimeType
  56.    * @param {string=} contentType
  57.    * @return {?shaka.extern.TransmuxerPlugin}
  58.    * @export
  59.    */
  60.   static findTransmuxer(mimeType, contentType) {
  61.     const TransmuxerEngine = shaka.transmuxer.TransmuxerEngine;
  62.     const normalizedMimetype = TransmuxerEngine.normalizeMimeType_(mimeType);
  63.     const priorities = [
  64.       TransmuxerEngine.PluginPriority.APPLICATION,
  65.       TransmuxerEngine.PluginPriority.PREFERRED,
  66.       TransmuxerEngine.PluginPriority.PREFERRED_SECONDARY,
  67.       TransmuxerEngine.PluginPriority.FALLBACK,
  68.     ];
  69.     for (const priority of priorities) {
  70.       const key = normalizedMimetype + '-' + priority;
  71.       const object = TransmuxerEngine.transmuxerMap_[key];
  72.       if (object) {
  73.         const transmuxer = object.plugin();
  74.         const isSupported = transmuxer.isSupported(mimeType, contentType);
  75.         transmuxer.destroy();
  76.         if (isSupported) {
  77.           return object.plugin;
  78.         }
  79.       }
  80.     }
  81.     return null;
  82.   }
  84.   /**
  85.    * @param {string} mimeType
  86.    * @return {string}
  87.    * @private
  88.    */
  89.   static normalizeMimeType_(mimeType) {
  90.     return mimeType.toLowerCase().split(';')[0];
  91.   }
  93.   /**
  94.    * Check if the mime type and the content type is supported.
  95.    * @param {string} mimeType
  96.    * @param {string=} contentType
  97.    * @return {boolean}
  98.    */
  99.   static isSupported(mimeType, contentType) {
  100.     const TransmuxerEngine = shaka.transmuxer.TransmuxerEngine;
  101.     const transmuxerPlugin = TransmuxerEngine.findTransmuxer(mimeType);
  102.     if (!transmuxerPlugin) {
  103.       return false;
  104.     }
  105.     return true;
  106.   }
  108.   /**
  109.    * For any stream, convert its codecs to MP4 codecs.
  110.    * @param {string} contentType
  111.    * @param {string} mimeType
  112.    * @return {string}
  113.    */
  114.   static convertCodecs(contentType, mimeType) {
  115.     const TransmuxerEngine = shaka.transmuxer.TransmuxerEngine;
  116.     const transmuxerPlugin = TransmuxerEngine.findTransmuxer(mimeType);
  117.     if (!transmuxerPlugin) {
  118.       return mimeType;
  119.     }
  120.     const transmuxer = transmuxerPlugin();
  121.     const codecs = transmuxer.convertCodecs(contentType, mimeType);
  122.     transmuxer.destroy();
  123.     return codecs;
  124.   }
  125. };
  128. /**
  129.  * @typedef {{
  130.  *   plugin: shaka.extern.TransmuxerPlugin,
  131.  *   priority: number
  132.  * }}
  133.  * @property {shaka.extern.TransmuxerPlugin} plugin
  134.  *   The associated plugin.
  135.  * @property {number} priority
  136.  *   The plugin's priority.
  137.  */
  138. shaka.transmuxer.TransmuxerEngine.PluginObject;
  141. /**
  142.  * @private {!Object.<string, !shaka.transmuxer.TransmuxerEngine.PluginObject>}
  143.  */
  144. shaka.transmuxer.TransmuxerEngine.transmuxerMap_ = {};
  147. /**
  148.  * Priority level for transmuxer plugins.
  149.  * If multiple plugins are provided for the same mime type, only the
  150.  * highest-priority one is used.
  151.  *
  152.  * @enum {number}
  153.  * @export
  154.  */
  155. shaka.transmuxer.TransmuxerEngine.PluginPriority = {
  156.   'FALLBACK': 1,
  157.   'PREFERRED_SECONDARY': 2,
  158.   'PREFERRED': 3,
  159.   'APPLICATION': 4,
  160. };