Source: lib/text/web_vtt_generator.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.text.WebVttGenerator');
  9. goog.require('shaka.text.Cue');
  10. goog.require('shaka.text.Utils');
  13. /**
  14.  * @summary Manage the conversion to WebVTT.
  15.  * @export
  16.  */
  17. shaka.text.WebVttGenerator = class {
  18.   /**
  19.    * @param {!Array<!shaka.text.Cue>} cues
  20.    * @param {!Array<!shaka.extern.AdCuePoint>} adCuePoints
  21.    * @return {string}
  22.    */
  23.   static convert(cues, adCuePoints) {
  24.     const webvttTimeString = (time) => {
  25.       let newTime = time;
  26.       for (const adCuePoint of adCuePoints) {
  27.         if (adCuePoint.end && adCuePoint.start < time) {
  28.           const offset = adCuePoint.end - adCuePoint.start;
  29.           newTime += offset;
  30.         }
  31.       }
  32.       const hours = Math.floor(newTime / 3600);
  33.       const minutes = Math.floor(newTime / 60 % 60);
  34.       const seconds = Math.floor(newTime % 60);
  35.       const milliseconds = Math.floor(newTime * 1000 % 1000);
  36.       return (hours < 10 ? '0' : '') + hours + ':' +
  37.           (minutes < 10 ? '0' : '') + minutes + ':' +
  38.           (seconds < 10 ? '0' : '') + seconds + '.' +
  39.           (milliseconds < 100 ? (milliseconds < 10 ? '00' : '0') : '') +
  40.           milliseconds;
  41.     };
  43.     const flattenedCues = shaka.text.Utils.getCuesToFlatten(cues);
  45.     let webvttString = 'WEBVTT\n\n';
  46.     for (const cue of flattenedCues) {
  47.       const webvttSettings = (cue) => {
  48.         const settings = [];
  49.         const Cue = shaka.text.Cue;
  50.         switch (cue.textAlign) {
  51.           case Cue.textAlign.LEFT:
  52.             settings.push('align:left');
  53.             break;
  54.           case Cue.textAlign.RIGHT:
  55.             settings.push('align:right');
  56.             break;
  57.           case Cue.textAlign.CENTER:
  58.             settings.push('align:middle');
  59.             break;
  60.           case Cue.textAlign.START:
  61.             settings.push('align:start');
  62.             break;
  63.           case Cue.textAlign.END:
  64.             settings.push('align:end');
  65.             break;
  66.         }
  67.         switch (cue.writingMode) {
  68.           case Cue.writingMode.VERTICAL_LEFT_TO_RIGHT:
  69.             settings.push('vertical:lr');
  70.             break;
  71.           case Cue.writingMode.VERTICAL_RIGHT_TO_LEFT:
  72.             settings.push('vertical:rl');
  73.             break;
  74.         }
  76.         if (settings.length) {
  77.           return ' ' + settings.join(' ');
  78.         }
  79.         return '';
  80.       };
  81.       webvttString += webvttTimeString(cue.startTime) + ' --> ' +
  82.           webvttTimeString(cue.endTime) + webvttSettings(cue) + '\n';
  83.       webvttString += cue.payload + '\n\n';
  84.     }
  85.     return webvttString;
  86.   }
  87. };