Source: lib/util/pssh.js

  1. /**
  2.  * @license
  3.  * Copyright 2016 Google Inc.
  4.  *
  5.  * Licensed under the Apache License, Version 2.0 (the "License");
  6.  * you may not use this file except in compliance with the License.
  7.  * You may obtain a copy of the License at
  8.  *
  9.  *     http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  18. goog.provide('shaka.util.Pssh');
  20. goog.require('goog.asserts');
  21. goog.require('shaka.log');
  22. goog.require('shaka.util.Mp4Parser');
  23. goog.require('shaka.util.Uint8ArrayUtils');
  27. /**
  28.  * Parse a PSSH box and extract the system IDs.
  29.  *
  30.  * @param {!Uint8Array} psshBox
  31.  * @constructor
  32.  * @struct
  33.  * @throws {shaka.util.Error} if a PSSH box is truncated or contains a size
  34.  *   field over 53 bits.
  35.  */
  36. shaka.util.Pssh = function(psshBox) {
  37.   /**
  38.    * In hex.
  39.    * @type {!Array.<string>}
  40.    */
  41.   this.systemIds = [];
  43.   /**
  44.    * In hex.
  45.    * @type {!Array.<string>}
  46.    */
  47.   this.cencKeyIds = [];
  49.   /*
  50.   * Array of tuples that define the startIndex + size for each
  51.   * discrete pssh within |psshBox|
  52.   * */
  53.   this.dataBoundaries = [];
  55.   new shaka.util.Mp4Parser()
  56.       .fullBox('pssh', this.parseBox_.bind(this)).parse(psshBox.buffer);
  58.   if (this.dataBoundaries.length == 0) {
  59.     shaka.log.warning('No pssh box found!');
  60.   }
  61. };
  64. /**
  65.  * @param {!shakaExtern.ParsedBox} box
  66.  * @private
  67.  */
  68. shaka.util.Pssh.prototype.parseBox_ = function(box) {
  69.   goog.asserts.assert(
  70.       box.version != null,
  71.       'PSSH boxes are full boxes and must have a valid version');
  73.   goog.asserts.assert(
  74.       box.flags != null,
  75.       'PSSH boxes are full boxes and must have a valid flag');
  77.   if (box.version > 1) {
  78.     shaka.log.warning('Unrecognized PSSH version found!');
  79.     return;
  80.   }
  82.   let systemId = shaka.util.Uint8ArrayUtils.toHex(box.reader.readBytes(16));
  83.   let keyIds = [];
  84.   if (box.version > 0) {
  85.     let numKeyIds = box.reader.readUint32();
  86.     for (let i = 0; i < numKeyIds; ++i) {
  87.       let keyId = shaka.util.Uint8ArrayUtils.toHex(box.reader.readBytes(16));
  88.       keyIds.push(keyId);
  89.     }
  90.   }
  92.   let dataSize = box.reader.readUint32();
  93.   box.reader.skip(dataSize);  // Ignore the data section.
  95.   // Now that everything has been succesfully parsed from this box,
  96.   // update member variables.
  97.   this.cencKeyIds.push.apply(this.cencKeyIds, keyIds);
  98.   this.systemIds.push(systemId);
  99.   this.dataBoundaries.push({
  100.     start: box.start,
  101.     end: box.start + box.size - 1
  102.   });
  104.   if (box.reader.getPosition() != box.reader.getLength()) {
  105.     shaka.log.warning('Mismatch between box size and data size!');
  106.   }
  107. };