☰

DASH Video Player Optimizer（视频协议优化DASH篇）

Optimize DASH video playback on web pages with enhanced performance and ABR management

  1. // ==UserScript==
  2. // @name         DASH Video Player Optimizer（视频协议优化DASH篇）
  3. // @namespace    http://tampermonkey.net/
  4. // @version      1.1
  5. // @description  Optimize DASH video playback on web pages with enhanced performance and ABR management
  6. // @author       KiwiFruit
  7. // @match        *://*/*
  8. // @grant        none
  9. // @license MIT
  10. // ==/UserScript==
  11. (function() {
  12.     'use strict';
  13.  
  14.     // Helper function to fetch the first segment of the DASH manifest
  15.     function fetchFirstSegment(mpdUrl) {
  16.         return fetch(mpdUrl)
  17.             .then(response => response.text())
  18.             .then(text => {
  19.                 const parser = new DOMParser();
  20.                 const xmlDoc = parser.parseFromString(text, "text/xml");
  21.                 // Find the first Representation and SegmentTemplate/BaseURL
  22.                 const representation = xmlDoc.querySelector('Representation');
  23.                 const segmentTemplate = representation.querySelector('SegmentTemplate');
  24.                 if (segmentTemplate) {
  25.                     const initialization = segmentTemplate.getAttribute('initialization');
  26.                     const baseUrl = xmlDoc.querySelector('BaseURL').textContent;
  27.                     return `${baseUrl}${initialization}`;
  28.                 } else {
  29.                     console.error('Failed to find the first segment URL.');
  30.                     return null;
  31.                 }
  32.             })
  33.             .catch(error => console.error('Error fetching first segment:', error));
  34.     }
  35.  
  36.     // Preload the first segment of the video using dash.js
  37.     function preloadFirstSegment(videoElement, player) {
  38.         const source = videoElement.querySelector('source');
  39.         if (source && source.src.endsWith('.mpd')) {
  40.             fetchFirstSegment(source.src).then(segmentUrl => {
  41.                 if (segmentUrl) {
  42.                     player.initialize(videoElement, source.src, true);
  43.                 }
  44.             });
  45.         }
  46.     }
  47.  
  48.     // Buffer strategy optimization
  49.     function optimizeBufferStrategy(player) {
  50.         player.on(dashjs.MediaPlayer.events.BUFFER_EMPTY, () => {
  51.             console.log('Buffer empty, pausing playback.');
  52.             player.pause();
  53.             // Dynamic buffer time based on average throughput
  54.             const bufferTime = player.getAverageThroughput() < 1000000 ? 3000 : 2000; // Adjust buffer time based on average throughput
  55.             setTimeout(() => {
  56.                 player.play();
  57.             }, bufferTime);
  58.         });
  59.  
  60.         player.on(dashjs.MediaPlayer.events.BUFFER_LOADED, () => {
  61.             console.log('Buffer loaded, resuming playback.');
  62.             player.play();
  63.         });
  64.     }
  65.  
  66.     // Helper function to dynamically load external scripts
  67.     function loadExternalScript(url, callback) {
  68.         var script = document.createElement('script');
  69.         script.src = url;
  70.         script.onload = function() {
  71.             console.log(url + ' loaded successfully.');
  72.             if (callback) callback();
  73.         };
  74.         script.onerror = function() {
  75.             console.error('Failed to load script: ' + url);
  76.         };
  77.         document.head.appendChild(script);
  78.     }
  79.  
  80.     // Main function to initialize optimizations
  81.     function initializeOptimizations() {
  82.         try {
  83.             const videoElement = document.querySelector('video');
  84.             if (!videoElement || !videoElement.querySelector('source[src$=".mpd"]')) return;
  85.  
  86.             // Dynamically load dashjs
  87.             loadExternalScript('https://cdn.jsdelivr.net/npm/dashjs@latest/dist/dash.all.min.js', () => {
  88.                 const player = dashjs.MediaPlayer().create();
  89.                 preloadFirstSegment(videoElement, player);
  90.                 optimizeBufferStrategy(player);
  91.             });
  92.         } catch (error) {
  93.             console.error('Error initializing optimizations:', error);
  94.         }
  95.     }
  96.  
  97.     // Run the initialization when the page loads
  98.     window.addEventListener('load', initializeOptimizations);
  99.  
  100.     // Compatibility check
  101.     if ('MediaSource' in window && MediaSource.isTypeSupported('video/mp4; codecs="avc1.42E01E, mp4a.40.2"')) {
  102.         initializeOptimizations();
  103.     } else {
  104.         console.warn('Your browser does not support DASH or MSE.');
  105.     }
  106. })();