mirror of
https://github.com/shaka-project/shaka-player.git
synced 2026-06-16 16:16:40 +03:00
Sandra Lokshina
128 lines
3.3 KiB
JavaScript
128 lines
3.3 KiB
JavaScript
/**
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* @license
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* Copyright 2016 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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goog.provide('shaka.util.Mp4Parser');
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goog.require('shaka.util.DataViewReader');
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/**
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* Looks for a box of a specified type in an mp4 stream and returns
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* it's size if found one. Returns -1 otherwise. Advances the
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* position of the reader to the beginning of the box content.
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* @param {number} boxType
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* @param {!shaka.util.DataViewReader} reader
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* @return {number}
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*/
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shaka.util.Mp4Parser.findBox = function(boxType, reader) {
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while (reader.hasMoreData()) {
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var start = reader.getPosition();
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var size = reader.readUint32();
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var type = reader.readUint32();
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if (size == 1) {
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size = reader.readUint64();
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} else if (size == 0) {
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size = reader.getLength() - start;
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}
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if (type == boxType) {
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return size;
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} else {
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reader.skip(size - (reader.getPosition() - start));
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continue;
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}
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}
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// couldn't find the box
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return shaka.util.Mp4Parser.BOX_NOT_FOUND;
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};
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/**
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* Finds a specified child of the sample description box
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* traversing a given path and returns it's size. Returns -1
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* if the box was not found.
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* @param {ArrayBuffer} data
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* @param {number} boxType
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* @return {number}
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*/
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shaka.util.Mp4Parser.findSampleDescriptionBox = function(data, boxType) {
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var reader = new shaka.util.DataViewReader(
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new DataView(data),
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shaka.util.DataViewReader.Endianness.BIG_ENDIAN);
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/* Path to a sample description box:
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moov->trak->mdia->minf->stpl->stsd->
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*/
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var Mp4Parser = shaka.util.Mp4Parser;
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var path = [
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//[box type, number of bytes to skip before getting to inner boxes
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// (for flags etc.)]
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[Mp4Parser.BOX_TYPE_MOOV, 0],
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[Mp4Parser.BOX_TYPE_TRAK, 0],
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[Mp4Parser.BOX_TYPE_MDIA, 0],
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[Mp4Parser.BOX_TYPE_MINF, 0],
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[Mp4Parser.BOX_TYPE_STBL, 0],
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[Mp4Parser.BOX_TYPE_STSD, 8],
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[boxType, 0]
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];
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var size = Mp4Parser.BOX_NOT_FOUND;
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for (var i = 0; i < path.length; i++) {
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var type = path[i][0];
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var skipBytes = path[i][1];
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size = Mp4Parser.findBox(type, reader);
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if (size == Mp4Parser.BOX_NOT_FOUND)
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return Mp4Parser.BOX_NOT_FOUND;
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reader.skip(skipBytes);
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}
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return size;
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};
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_NOT_FOUND = -1;
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_TYPE_MDAT = 0x6D646174;
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_TYPE_MOOV = 0x6D6F6F76;
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_TYPE_TRAK = 0x7472616B;
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_TYPE_MDIA = 0x6D646961;
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_TYPE_MINF = 0x6D696E66;
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_TYPE_STBL = 0x7374626C;
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/** @const {number} */
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shaka.util.Mp4Parser.BOX_TYPE_STSD = 0x73747364;
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