mirror of
https://github.com/shaka-project/shaka-player.git
synced 2026-06-15 16:06:41 +03:00
Michelle Zhuo
351 lines
11 KiB
JavaScript
351 lines
11 KiB
JavaScript
/**
|
|
* @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.media.WebmSegmentIndexParser');
|
|
|
|
goog.require('goog.asserts');
|
|
goog.require('shaka.log');
|
|
goog.require('shaka.media.SegmentReference');
|
|
goog.require('shaka.util.EbmlElement');
|
|
goog.require('shaka.util.EbmlParser');
|
|
goog.require('shaka.util.Error');
|
|
|
|
|
|
shaka.media.WebmSegmentIndexParser = class {
|
|
/**
|
|
* Parses SegmentReferences from a WebM container.
|
|
* @param {!ArrayBuffer} cuesData The WebM container's "Cueing Data" section.
|
|
* @param {!ArrayBuffer} initData The WebM container's headers.
|
|
* @param {!Array.<string>} uris The possible locations of the WebM file that
|
|
* contains the segments.
|
|
* @param {number} scaledPresentationTimeOffset
|
|
|
|
* @return {!Array.<!shaka.media.SegmentReference>}
|
|
* @throws {shaka.util.Error}
|
|
* @see http://www.matroska.org/technical/specs/index.html
|
|
* @see http://www.webmproject.org/docs/container/
|
|
*/
|
|
static parse(cuesData, initData, uris, scaledPresentationTimeOffset) {
|
|
const tuple =
|
|
shaka.media.WebmSegmentIndexParser.parseWebmContainer_(initData);
|
|
const parser = new shaka.util.EbmlParser(new DataView(cuesData));
|
|
const cuesElement = parser.parseElement();
|
|
if (cuesElement.id != shaka.media.WebmSegmentIndexParser.CUES_ID) {
|
|
shaka.log.error('Not a Cues element.');
|
|
throw new shaka.util.Error(
|
|
shaka.util.Error.Severity.CRITICAL,
|
|
shaka.util.Error.Category.MEDIA,
|
|
shaka.util.Error.Code.WEBM_CUES_ELEMENT_MISSING);
|
|
}
|
|
|
|
return shaka.media.WebmSegmentIndexParser.parseCues_(
|
|
cuesElement, tuple.segmentOffset, tuple.timecodeScale, tuple.duration,
|
|
uris, scaledPresentationTimeOffset);
|
|
}
|
|
|
|
|
|
/**
|
|
* Parses a WebM container to get the segment's offset, timecode scale, and
|
|
* duration.
|
|
*
|
|
* @param {!ArrayBuffer} initData
|
|
* @return {{segmentOffset: number, timecodeScale: number, duration: number}}
|
|
* The segment's offset in bytes, the segment's timecode scale in seconds,
|
|
* and the duration in seconds.
|
|
* @throws {shaka.util.Error}
|
|
* @private
|
|
*/
|
|
static parseWebmContainer_(initData) {
|
|
const parser = new shaka.util.EbmlParser(new DataView(initData));
|
|
|
|
// Check that the WebM container data starts with the EBML header, but
|
|
// skip its contents.
|
|
const ebmlElement = parser.parseElement();
|
|
if (ebmlElement.id != shaka.media.WebmSegmentIndexParser.EBML_ID) {
|
|
shaka.log.error('Not an EBML element.');
|
|
throw new shaka.util.Error(
|
|
shaka.util.Error.Severity.CRITICAL,
|
|
shaka.util.Error.Category.MEDIA,
|
|
shaka.util.Error.Code.WEBM_EBML_HEADER_ELEMENT_MISSING);
|
|
}
|
|
|
|
const segmentElement = parser.parseElement();
|
|
if (segmentElement.id != shaka.media.WebmSegmentIndexParser.SEGMENT_ID) {
|
|
shaka.log.error('Not a Segment element.');
|
|
throw new shaka.util.Error(
|
|
shaka.util.Error.Severity.CRITICAL,
|
|
shaka.util.Error.Category.MEDIA,
|
|
shaka.util.Error.Code.WEBM_SEGMENT_ELEMENT_MISSING);
|
|
}
|
|
|
|
// This value is used as the initial offset to the first referenced segment.
|
|
const segmentOffset = segmentElement.getOffset();
|
|
|
|
// Parse the Segment element to get the segment info.
|
|
const segmentInfo = shaka.media.WebmSegmentIndexParser.parseSegment_(
|
|
segmentElement);
|
|
return {
|
|
segmentOffset: segmentOffset,
|
|
timecodeScale: segmentInfo.timecodeScale,
|
|
duration: segmentInfo.duration,
|
|
};
|
|
}
|
|
|
|
|
|
/**
|
|
* Parses a WebM Info element to get the segment's timecode scale and
|
|
* duration.
|
|
* @param {!shaka.util.EbmlElement} segmentElement
|
|
* @return {{timecodeScale: number, duration: number}} The segment's timecode
|
|
* scale in seconds and duration in seconds.
|
|
* @throws {shaka.util.Error}
|
|
* @private
|
|
*/
|
|
static parseSegment_(segmentElement) {
|
|
const parser = segmentElement.createParser();
|
|
|
|
// Find the Info element.
|
|
let infoElement = null;
|
|
while (parser.hasMoreData()) {
|
|
const elem = parser.parseElement();
|
|
if (elem.id != shaka.media.WebmSegmentIndexParser.INFO_ID) {
|
|
continue;
|
|
}
|
|
|
|
infoElement = elem;
|
|
|
|
break;
|
|
}
|
|
|
|
if (!infoElement) {
|
|
shaka.log.error('Not an Info element.');
|
|
throw new shaka.util.Error(
|
|
shaka.util.Error.Severity.CRITICAL,
|
|
shaka.util.Error.Category.MEDIA,
|
|
shaka.util.Error.Code.WEBM_INFO_ELEMENT_MISSING);
|
|
}
|
|
|
|
return shaka.media.WebmSegmentIndexParser.parseInfo_(infoElement);
|
|
}
|
|
|
|
|
|
/**
|
|
* Parses a WebM Info element to get the segment's timecode scale and
|
|
* duration.
|
|
* @param {!shaka.util.EbmlElement} infoElement
|
|
* @return {{timecodeScale: number, duration: number}} The segment's timecode
|
|
* scale in seconds and duration in seconds.
|
|
* @throws {shaka.util.Error}
|
|
* @private
|
|
*/
|
|
static parseInfo_(infoElement) {
|
|
const parser = infoElement.createParser();
|
|
|
|
// The timecode scale factor in units of [nanoseconds / T], where [T] are
|
|
// the units used to express all other time values in the WebM container.
|
|
// By default it's assumed that [T] == [milliseconds].
|
|
let timecodeScaleNanoseconds = 1000000;
|
|
/** @type {?number} */
|
|
let durationScale = null;
|
|
|
|
while (parser.hasMoreData()) {
|
|
const elem = parser.parseElement();
|
|
if (elem.id == shaka.media.WebmSegmentIndexParser.TIMECODE_SCALE_ID) {
|
|
timecodeScaleNanoseconds = elem.getUint();
|
|
} else if (elem.id == shaka.media.WebmSegmentIndexParser.DURATION_ID) {
|
|
durationScale = elem.getFloat();
|
|
}
|
|
}
|
|
if (durationScale == null) {
|
|
throw new shaka.util.Error(
|
|
shaka.util.Error.Severity.CRITICAL,
|
|
shaka.util.Error.Category.MEDIA,
|
|
shaka.util.Error.Code.WEBM_DURATION_ELEMENT_MISSING);
|
|
}
|
|
|
|
// The timecode scale factor in units of [seconds / T].
|
|
const timecodeScale = timecodeScaleNanoseconds / 1000000000;
|
|
// The duration is stored in units of [T]
|
|
const durationSeconds = durationScale * timecodeScale;
|
|
|
|
return {timecodeScale: timecodeScale, duration: durationSeconds};
|
|
}
|
|
|
|
|
|
/**
|
|
* Parses a WebM CuesElement.
|
|
* @param {!shaka.util.EbmlElement} cuesElement
|
|
* @param {number} segmentOffset
|
|
* @param {number} timecodeScale
|
|
* @param {number} duration
|
|
* @param {!Array.<string>} uris
|
|
* @param {number} scaledPresentationTimeOffset
|
|
* @return {!Array.<!shaka.media.SegmentReference>}
|
|
* @throws {shaka.util.Error}
|
|
* @private
|
|
*/
|
|
static parseCues_(cuesElement, segmentOffset, timecodeScale, duration,
|
|
uris, scaledPresentationTimeOffset) {
|
|
const references = [];
|
|
const getUris = () => uris;
|
|
|
|
const parser = cuesElement.createParser();
|
|
|
|
let lastTime = null;
|
|
let lastOffset = null;
|
|
|
|
while (parser.hasMoreData()) {
|
|
const elem = parser.parseElement();
|
|
if (elem.id != shaka.media.WebmSegmentIndexParser.CUE_POINT_ID) {
|
|
continue;
|
|
}
|
|
|
|
const tuple = shaka.media.WebmSegmentIndexParser.parseCuePoint_(elem);
|
|
if (!tuple) {
|
|
continue;
|
|
}
|
|
|
|
// Substract the presentation time offset from the unscaled time
|
|
const currentTime = timecodeScale * tuple.unscaledTime;
|
|
const currentOffset = segmentOffset + tuple.relativeOffset;
|
|
|
|
if (lastTime != null) {
|
|
goog.asserts.assert(lastOffset != null, 'last offset cannot be null');
|
|
|
|
references.push(
|
|
new shaka.media.SegmentReference(
|
|
references.length,
|
|
lastTime - scaledPresentationTimeOffset,
|
|
currentTime - scaledPresentationTimeOffset,
|
|
getUris,
|
|
lastOffset, currentOffset - 1));
|
|
}
|
|
|
|
lastTime = currentTime;
|
|
lastOffset = currentOffset;
|
|
}
|
|
|
|
if (lastTime != null) {
|
|
goog.asserts.assert(lastOffset != null, 'last offset cannot be null');
|
|
|
|
references.push(
|
|
new shaka.media.SegmentReference(
|
|
references.length,
|
|
lastTime - scaledPresentationTimeOffset,
|
|
duration - scaledPresentationTimeOffset,
|
|
getUris,
|
|
lastOffset, null));
|
|
}
|
|
|
|
return references;
|
|
}
|
|
|
|
|
|
/**
|
|
* Parses a WebM CuePointElement to get an "unadjusted" segment reference.
|
|
* @param {shaka.util.EbmlElement} cuePointElement
|
|
* @return {{unscaledTime: number, relativeOffset: number}} The referenced
|
|
* segment's start time in units of [T] (see parseInfo_()), and the
|
|
* referenced segment's offset in bytes, relative to a WebM Segment
|
|
* element.
|
|
* @throws {shaka.util.Error}
|
|
* @private
|
|
*/
|
|
static parseCuePoint_(cuePointElement) {
|
|
const parser = cuePointElement.createParser();
|
|
|
|
// Parse CueTime element.
|
|
const cueTimeElement = parser.parseElement();
|
|
if (cueTimeElement.id != shaka.media.WebmSegmentIndexParser.CUE_TIME_ID) {
|
|
shaka.log.warning('Not a CueTime element.');
|
|
throw new shaka.util.Error(
|
|
shaka.util.Error.Severity.CRITICAL,
|
|
shaka.util.Error.Category.MEDIA,
|
|
shaka.util.Error.Code.WEBM_CUE_TIME_ELEMENT_MISSING);
|
|
}
|
|
const unscaledTime = cueTimeElement.getUint();
|
|
|
|
// Parse CueTrackPositions element.
|
|
const cueTrackPositionsElement = parser.parseElement();
|
|
if (cueTrackPositionsElement.id !=
|
|
shaka.media.WebmSegmentIndexParser.CUE_TRACK_POSITIONS_ID) {
|
|
shaka.log.warning('Not a CueTrackPositions element.');
|
|
throw new shaka.util.Error(
|
|
shaka.util.Error.Severity.CRITICAL,
|
|
shaka.util.Error.Category.MEDIA,
|
|
shaka.util.Error.Code.WEBM_CUE_TRACK_POSITIONS_ELEMENT_MISSING);
|
|
}
|
|
|
|
const cueTrackParser = cueTrackPositionsElement.createParser();
|
|
let relativeOffset = 0;
|
|
|
|
while (cueTrackParser.hasMoreData()) {
|
|
const elem = cueTrackParser.parseElement();
|
|
if (elem.id != shaka.media.WebmSegmentIndexParser.CUE_CLUSTER_POSITION) {
|
|
continue;
|
|
}
|
|
|
|
relativeOffset = elem.getUint();
|
|
break;
|
|
}
|
|
|
|
return {unscaledTime: unscaledTime, relativeOffset: relativeOffset};
|
|
}
|
|
};
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.EBML_ID = 0x1a45dfa3;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.SEGMENT_ID = 0x18538067;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.INFO_ID = 0x1549a966;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.TIMECODE_SCALE_ID = 0x2ad7b1;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.DURATION_ID = 0x4489;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.CUES_ID = 0x1c53bb6b;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.CUE_POINT_ID = 0xbb;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.CUE_TIME_ID = 0xb3;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.CUE_TRACK_POSITIONS_ID = 0xb7;
|
|
|
|
|
|
/** @const {number} */
|
|
shaka.media.WebmSegmentIndexParser.CUE_CLUSTER_POSITION = 0xf1;
|
|
|
|
|