shaka-player/lib/text/mp4_ttml_parser.js

DASH/EME video player library

/**
 * @license
 * Copyright 2016 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

goog.provide('shaka.text.Mp4TtmlParser');

goog.require('shaka.text.TextEngine');
goog.require('shaka.text.TtmlTextParser');
goog.require('shaka.util.Error');
goog.require('shaka.util.Mp4Parser');


/**
 * @struct
 * @constructor
 * @implements {shaka.extern.TextParser}
 * @export
 */
shaka.text.Mp4TtmlParser = function() {
  /**
   * @type {!shaka.extern.TextParser}
   * @private
   */
  this.parser_ = new shaka.text.TtmlTextParser();
};


/**
 * @override
 * @export
 */
shaka.text.Mp4TtmlParser.prototype.parseInit = function(data) {
  const Mp4Parser = shaka.util.Mp4Parser;

  let sawSTPP = false;

  new Mp4Parser()
      .box('moov', Mp4Parser.children)
      .box('trak', Mp4Parser.children)
      .box('mdia', Mp4Parser.children)
      .box('minf', Mp4Parser.children)
      .box('stbl', Mp4Parser.children)
      .fullBox('stsd', Mp4Parser.sampleDescription)
      .box('stpp', function(box) {
        sawSTPP = true;
        box.parser.stop();
      }).parse(data);

  if (!sawSTPP) {
    throw new shaka.util.Error(
        shaka.util.Error.Severity.CRITICAL,
        shaka.util.Error.Category.TEXT,
        shaka.util.Error.Code.INVALID_MP4_TTML);
  }
};


/**
 * @override
 * @export
 */
shaka.text.Mp4TtmlParser.prototype.parseMedia = function(data, time) {
  const Mp4Parser = shaka.util.Mp4Parser;

  let sawMDAT = false;
  let payload = [];

  new Mp4Parser()
      .box('mdat', Mp4Parser.allData(function(data) {
        sawMDAT = true;
        // Join this to any previous payload, in case the mp4 has multiple
        // mdats.
        payload = payload.concat(this.parser_.parseMedia(data, time));
      }.bind(this))).parse(data);

  if (!sawMDAT) {
    throw new shaka.util.Error(
        shaka.util.Error.Severity.CRITICAL,
        shaka.util.Error.Category.TEXT,
        shaka.util.Error.Code.INVALID_MP4_TTML);
  }

  return payload;
};


shaka.text.TextEngine.registerParser(
    'application/mp4; codecs="stpp"', shaka.text.Mp4TtmlParser);
shaka.text.TextEngine.registerParser(
    'application/mp4; codecs="stpp.ttml.im1t"', shaka.text.Mp4TtmlParser);
// Legacy codec string uses capital "TTML", i.e.: prior to HLS rfc8216bis:
//   Note that if a Variant Stream specifies one or more Renditions that
//   include IMSC subtitles, the CODECS attribute MUST indicate this with a
//   format identifier such as "stpp.ttml.im1t".
// (https://tools.ietf.org/html/draft-pantos-hls-rfc8216bis-05#section-4.4.5.2)
shaka.text.TextEngine.registerParser(
    'application/mp4; codecs="stpp.TTML.im1t"', shaka.text.Mp4TtmlParser);