shaka-player
Version:
DASH/EME video player library
459 lines (400 loc) • 16.4 kB
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.dash.SegmentTemplate');
goog.require('goog.asserts');
goog.require('shaka.dash.MpdUtils');
goog.require('shaka.dash.SegmentBase');
goog.require('shaka.log');
goog.require('shaka.media.InitSegmentReference');
goog.require('shaka.media.SegmentIndex');
goog.require('shaka.media.SegmentReference');
goog.require('shaka.util.Error');
goog.require('shaka.util.ManifestParserUtils');
/**
* @namespace shaka.dash.SegmentTemplate
* @summary A set of functions for parsing SegmentTemplate elements.
*/
/**
* Creates a new Stream object or updates the Stream in the manifest.
*
* @param {shaka.dash.DashParser.Context} context
* @param {shaka.dash.DashParser.RequestInitSegmentCallback} requestInitSegment
* @param {!Object.<string, !shaka.media.SegmentIndex>} segmentIndexMap
* @param {boolean} isUpdate True if the manifest is being updated.
* @throws shaka.util.Error When there is a parsing error.
* @return {shaka.dash.DashParser.StreamInfo}
*/
shaka.dash.SegmentTemplate.createStream = function(
context, requestInitSegment, segmentIndexMap, isUpdate) {
goog.asserts.assert(context.representation.segmentTemplate,
'Should only be called with SegmentTemplate');
const SegmentTemplate = shaka.dash.SegmentTemplate;
let init = SegmentTemplate.createInitSegment_(context);
let info = SegmentTemplate.parseSegmentTemplateInfo_(context);
SegmentTemplate.checkSegmentTemplateInfo_(context, info);
/** @type {?shaka.dash.DashParser.SegmentIndexFunctions} */
let segmentIndexFunctions = null;
if (info.indexTemplate) {
segmentIndexFunctions = SegmentTemplate.createFromIndexTemplate_(
context, requestInitSegment, init, info);
} else if (info.segmentDuration) {
if (!isUpdate) {
context.presentationTimeline.notifyMaxSegmentDuration(
info.segmentDuration);
context.presentationTimeline.notifyMinSegmentStartTime(
context.periodInfo.start);
}
segmentIndexFunctions = SegmentTemplate.createFromDuration_(context, info);
} else {
/** @type {shaka.media.SegmentIndex} */
let segmentIndex = null;
let id = null;
if (context.period.id && context.representation.id) {
// Only check/store the index if period and representation IDs are set.
id = context.period.id + ',' + context.representation.id;
segmentIndex = segmentIndexMap[id];
}
let references = SegmentTemplate.createFromTimeline_(context, info);
// Don't fit live content, since it might receive more segments.
// Unless that live content is multi-period; it's safe to fit every period
// but the last one, since only the last period might receive new segments.
let shouldFit = !context.dynamic || !context.periodInfo.isLastPeriod;
if (segmentIndex) {
if (shouldFit) {
// Fit the new references before merging them, so that the merge
// algorithm has a more accurate view of their start and end times.
let wrapper = new shaka.media.SegmentIndex(references);
wrapper.fit(context.periodInfo.duration);
}
segmentIndex.merge(references);
let start = context.presentationTimeline.getSegmentAvailabilityStart();
segmentIndex.evict(start - context.periodInfo.start);
} else {
context.presentationTimeline.notifySegments(
references, context.periodInfo.start);
segmentIndex = new shaka.media.SegmentIndex(references);
if (id && context.dynamic) {
segmentIndexMap[id] = segmentIndex;
}
}
if (shouldFit) {
segmentIndex.fit(context.periodInfo.duration);
}
segmentIndexFunctions = {
createSegmentIndex: Promise.resolve.bind(Promise),
findSegmentPosition: segmentIndex.find.bind(segmentIndex),
getSegmentReference: segmentIndex.get.bind(segmentIndex),
};
}
return {
createSegmentIndex: segmentIndexFunctions.createSegmentIndex,
findSegmentPosition: segmentIndexFunctions.findSegmentPosition,
getSegmentReference: segmentIndexFunctions.getSegmentReference,
initSegmentReference: init,
scaledPresentationTimeOffset: info.scaledPresentationTimeOffset,
};
};
/**
* @typedef {{
* timescale: number,
* segmentDuration: ?number,
* startNumber: number,
* scaledPresentationTimeOffset: number,
* unscaledPresentationTimeOffset: number,
* timeline: Array.<shaka.dash.MpdUtils.TimeRange>,
* mediaTemplate: ?string,
* indexTemplate: ?string
* }}
* @private
*
* @description
* Contains information about a SegmentTemplate.
*
* @property {number} timescale
* The time-scale of the representation.
* @property {?number} segmentDuration
* The duration of the segments in seconds, if given.
* @property {number} startNumber
* The start number of the segments; 1 or greater.
* @property {number} scaledPresentationTimeOffset
* The presentation time offset of the representation, in seconds.
* @property {number} unscaledPresentationTimeOffset
* The presentation time offset of the representation, in timescale units.
* @property {Array.<shaka.dash.MpdUtils.TimeRange>} timeline
* The timeline of the representation, if given. Times in seconds.
* @property {?string} mediaTemplate
* The media URI template, if given.
* @property {?string} indexTemplate
* The index URI template, if given.
*/
shaka.dash.SegmentTemplate.SegmentTemplateInfo;
/**
* @param {?shaka.dash.DashParser.InheritanceFrame} frame
* @return {Element}
* @private
*/
shaka.dash.SegmentTemplate.fromInheritance_ = function(frame) {
return frame.segmentTemplate;
};
/**
* Parses a SegmentTemplate element into an info object.
*
* @param {shaka.dash.DashParser.Context} context
* @return {shaka.dash.SegmentTemplate.SegmentTemplateInfo}
* @private
*/
shaka.dash.SegmentTemplate.parseSegmentTemplateInfo_ = function(context) {
const SegmentTemplate = shaka.dash.SegmentTemplate;
const MpdUtils = shaka.dash.MpdUtils;
let segmentInfo =
MpdUtils.parseSegmentInfo(context, SegmentTemplate.fromInheritance_);
let media = MpdUtils.inheritAttribute(
context, SegmentTemplate.fromInheritance_, 'media');
let index = MpdUtils.inheritAttribute(
context, SegmentTemplate.fromInheritance_, 'index');
return {
segmentDuration: segmentInfo.segmentDuration,
timescale: segmentInfo.timescale,
startNumber: segmentInfo.startNumber,
scaledPresentationTimeOffset: segmentInfo.scaledPresentationTimeOffset,
unscaledPresentationTimeOffset: segmentInfo.unscaledPresentationTimeOffset,
timeline: segmentInfo.timeline,
mediaTemplate: media,
indexTemplate: index,
};
};
/**
* Verifies a SegmentTemplate info object.
*
* @param {shaka.dash.DashParser.Context} context
* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
* @throws shaka.util.Error When there is a parsing error.
* @private
*/
shaka.dash.SegmentTemplate.checkSegmentTemplateInfo_ = function(context, info) {
let n = 0;
n += info.indexTemplate ? 1 : 0;
n += info.timeline ? 1 : 0;
n += info.segmentDuration ? 1 : 0;
if (n == 0) {
shaka.log.error(
'SegmentTemplate does not contain any segment information:',
'the SegmentTemplate must contain either an index URL template',
'a SegmentTimeline, or a segment duration.',
context.representation);
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.DASH_NO_SEGMENT_INFO);
} else if (n != 1) {
shaka.log.warning(
'SegmentTemplate containes multiple segment information sources:',
'the SegmentTemplate should only contain an index URL template,',
'a SegmentTimeline or a segment duration.',
context.representation);
if (info.indexTemplate) {
shaka.log.info('Using the index URL template by default.');
info.timeline = null;
info.segmentDuration = null;
} else {
goog.asserts.assert(info.timeline, 'There should be a timeline');
shaka.log.info('Using the SegmentTimeline by default.');
info.segmentDuration = null;
}
}
if (!info.indexTemplate && !info.mediaTemplate) {
shaka.log.error(
'SegmentTemplate does not contain sufficient segment information:',
'the SegmentTemplate\'s media URL template is missing.',
context.representation);
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.DASH_NO_SEGMENT_INFO);
}
};
/**
* Creates segment index functions from a index URL template.
*
* @param {shaka.dash.DashParser.Context} context
* @param {shaka.dash.DashParser.RequestInitSegmentCallback} requestInitSegment
* @param {shaka.media.InitSegmentReference} init
* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
* @throws shaka.util.Error When there is a parsing error.
* @return {shaka.dash.DashParser.SegmentIndexFunctions}
* @private
*/
shaka.dash.SegmentTemplate.createFromIndexTemplate_ = function(
context, requestInitSegment, init, info) {
const MpdUtils = shaka.dash.MpdUtils;
const ManifestParserUtils = shaka.util.ManifestParserUtils;
// Determine the container type.
let containerType = context.representation.mimeType.split('/')[1];
if ((containerType != 'mp4') && (containerType != 'webm')) {
shaka.log.error(
'SegmentTemplate specifies an unsupported container type.',
context.representation);
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.DASH_UNSUPPORTED_CONTAINER);
}
if ((containerType == 'webm') && !init) {
shaka.log.error(
'SegmentTemplate does not contain sufficient segment information:',
'the SegmentTemplate uses a WebM container,',
'but does not contain an initialization URL template.',
context.representation);
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.DASH_WEBM_MISSING_INIT);
}
goog.asserts.assert(info.indexTemplate, 'must be using index template');
let filledTemplate = MpdUtils.fillUriTemplate(
info.indexTemplate, context.representation.id,
null, context.bandwidth || null, null);
let resolvedUris = ManifestParserUtils.resolveUris(
context.representation.baseUris, [filledTemplate]);
return shaka.dash.SegmentBase.createSegmentIndexFromUris(
context, requestInitSegment, init, resolvedUris, 0, null, containerType,
info.scaledPresentationTimeOffset);
};
/**
* Creates segment index functions from a segment duration.
*
* @param {shaka.dash.DashParser.Context} context
* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
* @return {shaka.dash.DashParser.SegmentIndexFunctions}
* @private
*/
shaka.dash.SegmentTemplate.createFromDuration_ = function(context, info) {
goog.asserts.assert(info.mediaTemplate,
'There should be a media template with duration');
const MpdUtils = shaka.dash.MpdUtils;
const ManifestParserUtils = shaka.util.ManifestParserUtils;
let periodDuration = context.periodInfo.duration;
let segmentDuration = info.segmentDuration;
let startNumber = info.startNumber;
let timescale = info.timescale;
let template = info.mediaTemplate;
let bandwidth = context.bandwidth || null;
let id = context.representation.id;
let baseUris = context.representation.baseUris;
let find = function(periodTime) {
if (periodTime < 0) {
return null;
} else if (periodDuration && periodTime >= periodDuration) {
return null;
}
return Math.floor(periodTime / segmentDuration);
};
let get = function(position) {
let segmentStart = position * segmentDuration;
// Cap the segment end at the period end, to avoid period transition issues
// in StreamingEngine.
let segmentEnd = segmentStart + segmentDuration;
if (periodDuration) segmentEnd = Math.min(segmentEnd, periodDuration);
// Do not construct segments references that should not exist.
if (segmentEnd < 0) {
return null;
} else if (periodDuration && segmentStart >= periodDuration) {
return null;
}
let getUris = function() {
let mediaUri = MpdUtils.fillUriTemplate(
template, id, position + startNumber, bandwidth,
segmentStart * timescale);
return ManifestParserUtils.resolveUris(baseUris, [mediaUri]);
};
return new shaka.media.SegmentReference(
position, segmentStart, segmentEnd, getUris, 0, null);
};
return {
createSegmentIndex: Promise.resolve.bind(Promise),
findSegmentPosition: find,
getSegmentReference: get,
};
};
/**
* Creates segment references from a timeline.
*
* @param {shaka.dash.DashParser.Context} context
* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
* @return {!Array.<!shaka.media.SegmentReference>}
* @private
*/
shaka.dash.SegmentTemplate.createFromTimeline_ = function(context, info) {
goog.asserts.assert(info.mediaTemplate,
'There should be a media template with a timeline');
const MpdUtils = shaka.dash.MpdUtils;
const ManifestParserUtils = shaka.util.ManifestParserUtils;
/** @type {!Array.<!shaka.media.SegmentReference>} */
let references = [];
for (let i = 0; i < info.timeline.length; i++) {
let start = info.timeline[i].start;
let unscaledStart = info.timeline[i].unscaledStart;
let end = info.timeline[i].end;
// Note: i = k - 1, where k indicates the k'th segment listed in the MPD.
// (See section 5.3.9.5.3 of the DASH spec.)
let segmentReplacement = i + info.startNumber;
// Consider the presentation time offset in segment uri computation
let timeReplacement = unscaledStart +
info.unscaledPresentationTimeOffset;
let createUris = (function(
template, repId, bandwidth, baseUris, segmentId, time) {
let mediaUri = MpdUtils.fillUriTemplate(
template, repId, segmentId, bandwidth, time);
return ManifestParserUtils.resolveUris(baseUris, [mediaUri])
.map(function(g) { return g.toString(); });
}.bind(null, info.mediaTemplate, context.representation.id,
context.bandwidth || null, context.representation.baseUris,
segmentReplacement, timeReplacement));
references.push(new shaka.media.SegmentReference(
segmentReplacement, start, end, createUris, 0, null));
}
return references;
};
/**
* Creates an init segment reference from a context object.
*
* @param {shaka.dash.DashParser.Context} context
* @return {shaka.media.InitSegmentReference}
* @private
*/
shaka.dash.SegmentTemplate.createInitSegment_ = function(context) {
const MpdUtils = shaka.dash.MpdUtils;
const ManifestParserUtils = shaka.util.ManifestParserUtils;
const SegmentTemplate = shaka.dash.SegmentTemplate;
let initialization = MpdUtils.inheritAttribute(
context, SegmentTemplate.fromInheritance_, 'initialization');
if (!initialization) {
return null;
}
let repId = context.representation.id;
let bandwidth = context.bandwidth || null;
let baseUris = context.representation.baseUris;
let getUris = function() {
goog.asserts.assert(initialization, 'Should have returned earler');
let filledTemplate = MpdUtils.fillUriTemplate(
initialization, repId, null, bandwidth, null);
let resolvedUris = ManifestParserUtils.resolveUris(
baseUris, [filledTemplate]);
return resolvedUris;
};
return new shaka.media.InitSegmentReference(getUris, 0, null);
};