Source: lib/text/mp4_ttml_parser.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.text.Mp4TtmlParser');
  9. goog.require('goog.asserts');
  10. goog.require('shaka.text.TextEngine');
  11. goog.require('shaka.text.TtmlTextParser');
  12. goog.require('shaka.util.BufferUtils');
  13. goog.require('shaka.util.Error');
  14. goog.require('shaka.util.Mp4BoxParsers');
  15. goog.require('shaka.util.Mp4Parser');
  16. goog.require('shaka.util.Uint8ArrayUtils');
  19. /**
  20.  * @implements {shaka.extern.TextParser}
  21.  * @export
  22.  */
  23. shaka.text.Mp4TtmlParser = class {
  24.   /** */
  25.   constructor() {
  26.     /**
  27.      * @type {!shaka.extern.TextParser}
  28.      * @private
  29.      */
  30.     this.parser_ = new shaka.text.TtmlTextParser();
  31.   }
  33.   /**
  34.    * @override
  35.    * @export
  36.    */
  37.   parseInit(data) {
  38.     const Mp4Parser = shaka.util.Mp4Parser;
  40.     let sawSTPP = false;
  42.     new Mp4Parser()
  43.         .box('moov', Mp4Parser.children)
  44.         .box('trak', Mp4Parser.children)
  45.         .box('mdia', Mp4Parser.children)
  46.         .box('minf', Mp4Parser.children)
  47.         .box('stbl', Mp4Parser.children)
  48.         .fullBox('stsd', Mp4Parser.sampleDescription)
  49.         .box('stpp', (box) => {
  50.           sawSTPP = true;
  51.           box.parser.stop();
  52.         }).parse(data);
  54.     if (!sawSTPP) {
  55.       throw new shaka.util.Error(
  56.           shaka.util.Error.Severity.CRITICAL,
  57.           shaka.util.Error.Category.TEXT,
  58.           shaka.util.Error.Code.INVALID_MP4_TTML);
  59.     }
  60.   }
  62.   /**
  63.    * @override
  64.    * @export
  65.    */
  66.   setSequenceMode(sequenceMode) {
  67.     // Unused.
  68.   }
  70.   /**
  71.    * @override
  72.    * @export
  73.    */
  74.   setManifestType(manifestType) {
  75.     // Unused.
  76.   }
  78.   /**
  79.    * @override
  80.    * @export
  81.    */
  82.   parseMedia(data, time, uri) {
  83.     const Mp4Parser = shaka.util.Mp4Parser;
  85.     let payload = [];
  86.     let defaultSampleSize = null;
  88.     /** @type {!Array<Uint8Array>} */
  89.     const mdats = [];
  91.     /* @type {!Map<number,!Array<number>>} */
  92.     const subSampleSizesPerSample = new Map();
  94.     /** @type {!Array<number>} */
  95.     const sampleSizes = [];
  97.     const parser = new Mp4Parser()
  98.         .box('moof', Mp4Parser.children)
  99.         .box('traf', Mp4Parser.children)
  100.         .fullBox('tfhd', (box) => {
  101.           goog.asserts.assert(
  102.               box.flags != null,
  103.               'A TFHD box should have a valid flags value');
  104.           const parsedTFHDBox = shaka.util.Mp4BoxParsers.parseTFHD(
  105.               box.reader, box.flags);
  106.           defaultSampleSize = parsedTFHDBox.defaultSampleSize;
  107.         })
  108.         .fullBox('trun', (box) => {
  109.           goog.asserts.assert(
  110.               box.version != null,
  111.               'A TRUN box should have a valid version value');
  112.           goog.asserts.assert(
  113.               box.flags != null,
  114.               'A TRUN box should have a valid flags value');
  116.           const parsedTRUNBox = shaka.util.Mp4BoxParsers.parseTRUN(
  117.               box.reader, box.version, box.flags);
  119.           for (const sample of parsedTRUNBox.sampleData) {
  120.             const sampleSize =
  121.                 sample.sampleSize || defaultSampleSize || 0;
  122.             sampleSizes.push(sampleSize);
  123.           }
  124.         })
  125.         .fullBox('subs', (box) => {
  126.           const reader = box.reader;
  127.           const entryCount = reader.readUint32();
  128.           let currentSampleNum = -1;
  129.           for (let i = 0; i < entryCount; i++) {
  130.             const sampleDelta = reader.readUint32();
  131.             currentSampleNum += sampleDelta;
  132.             const subsampleCount = reader.readUint16();
  133.             const subsampleSizes = [];
  134.             for (let j = 0; j < subsampleCount; j++) {
  135.               if (box.version == 1) {
  136.                 subsampleSizes.push(reader.readUint32());
  137.               } else {
  138.                 subsampleSizes.push(reader.readUint16());
  139.               }
  140.               reader.readUint8(); // priority
  141.               reader.readUint8(); // discardable
  142.               reader.readUint32(); // codec_specific_parameters
  143.             }
  144.             subSampleSizesPerSample.set(currentSampleNum, subsampleSizes);
  145.           }
  146.         })
  147.         .box('mdat', Mp4Parser.allData((data) => {
  148.           // We collect all of the mdats first, before parsing any of them.
  149.           // This is necessary in case the mp4 has multiple mdats.
  150.           mdats.push(data);
  151.         }));
  152.     parser.parse(data, /* partialOkay= */ false);
  154.     if (mdats.length == 0) {
  155.       throw new shaka.util.Error(
  156.           shaka.util.Error.Severity.CRITICAL,
  157.           shaka.util.Error.Category.TEXT,
  158.           shaka.util.Error.Code.INVALID_MP4_TTML);
  159.     }
  161.     const fullData =
  162.         shaka.util.Uint8ArrayUtils.concat(...mdats);
  164.     let sampleOffset = 0;
  165.     for (let sampleNum = 0; sampleNum < sampleSizes.length; sampleNum++) {
  166.       const sampleData =
  167.           shaka.util.BufferUtils.toUint8(fullData, sampleOffset,
  168.               sampleSizes[sampleNum]);
  169.       sampleOffset += sampleSizes[sampleNum];
  171.       const subSampleSizes = subSampleSizesPerSample.get(sampleNum);
  173.       if (subSampleSizes && subSampleSizes.length) {
  174.         const contentData =
  175.             shaka.util.BufferUtils.toUint8(sampleData, 0, subSampleSizes[0]);
  176.         const images = [];
  177.         let subOffset = subSampleSizes[0];
  178.         for (let i = 1; i < subSampleSizes.length; i++) {
  179.           const imageData =
  180.               shaka.util.BufferUtils.toUint8(data, subOffset,
  181.                   subSampleSizes[i]);
  182.           const raw =
  183.               shaka.util.Uint8ArrayUtils.toStandardBase64(imageData);
  184.           images.push('data:image/png;base64,' + raw);
  185.           subOffset += subSampleSizes[i];
  186.         }
  187.         payload = payload.concat(
  188.             this.parser_.parseMedia(contentData, time, uri, images));
  189.       } else {
  190.         payload = payload.concat(
  191.             this.parser_.parseMedia(sampleData, time, uri,
  192.                 /* images= */ []));
  193.       }
  194.     }
  196.     return payload;
  197.   }
  198. };
  201. shaka.text.TextEngine.registerParser(
  202.     'application/mp4; codecs="stpp"', () => new shaka.text.Mp4TtmlParser());
  203. shaka.text.TextEngine.registerParser(
  204.     'application/mp4; codecs="stpp.ttml"',
  205.     () => new shaka.text.Mp4TtmlParser());
  206. shaka.text.TextEngine.registerParser(
  207.     'application/mp4; codecs="stpp.ttml.im1i"',
  208.     () => new shaka.text.Mp4TtmlParser());
  209. shaka.text.TextEngine.registerParser(
  210.     'application/mp4; codecs="stpp.ttml.im1t"',
  211.     () => new shaka.text.Mp4TtmlParser());
  212. shaka.text.TextEngine.registerParser(
  213.     'application/mp4; codecs="stpp.ttml.im2i"',
  214.     () => new shaka.text.Mp4TtmlParser());
  215. shaka.text.TextEngine.registerParser(
  216.     'application/mp4; codecs="stpp.ttml.im2t"',
  217.     () => new shaka.text.Mp4TtmlParser());
  218. shaka.text.TextEngine.registerParser(
  219.     'application/mp4; codecs="stpp.ttml.etd1"',
  220.     () => new shaka.text.Mp4TtmlParser());
  221. shaka.text.TextEngine.registerParser(
  222.     'application/mp4; codecs="stpp.ttml.etd1|im1t"',
  223.     () => new shaka.text.Mp4TtmlParser());
  224. shaka.text.TextEngine.registerParser(
  225.     'application/mp4; codecs="stpp.ttml.im1t|etd1"',
  226.     () => new shaka.text.Mp4TtmlParser());
  228. // Legacy codec string uses capital "TTML", i.e.: prior to HLS rfc8216bis:
  229. //   Note that if a Variant Stream specifies one or more Renditions that
  230. //   include IMSC subtitles, the CODECS attribute MUST indicate this with a
  231. //   format identifier such as "stpp.ttml.im1t".
  232. // (https://tools.ietf.org/html/draft-pantos-hls-rfc8216bis-05#section-4.4.5.2)
  233. shaka.text.TextEngine.registerParser(
  234.     'application/mp4; codecs="stpp.TTML.im1t"',
  235.     () => new shaka.text.Mp4TtmlParser());