mirror of
https://github.com/shaka-project/shaka-player.git
synced 2026-06-15 16:06:41 +03:00
Jacob Trimble
47533d1173
This is a helper to aid in iterating over items. This returns a list of objects that contain: - "item": The current value. - "prev": The previous value in the list. - "next": The next value in the list. - "i": The zero-based index in the list. Issue #1518 Change-Id: Id18ab977e3ae45dfbfd2b4137a1bffb6e53c6bce
456 lines
16 KiB
JavaScript
456 lines
16 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.dash.SegmentTemplate');
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goog.require('goog.asserts');
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goog.require('shaka.dash.MpdUtils');
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goog.require('shaka.dash.SegmentBase');
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goog.require('shaka.log');
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goog.require('shaka.media.InitSegmentReference');
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goog.require('shaka.media.SegmentIndex');
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goog.require('shaka.media.SegmentReference');
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goog.require('shaka.util.Error');
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goog.require('shaka.util.Iterables');
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goog.require('shaka.util.ManifestParserUtils');
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/**
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* @summary A set of functions for parsing SegmentTemplate elements.
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*/
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shaka.dash.SegmentTemplate = class {
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/**
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* Creates a new Stream object or updates the Stream in the manifest.
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*
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* @param {shaka.dash.DashParser.Context} context
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* @param {shaka.dash.DashParser.RequestInitSegmentCallback}
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* requestInitSegment
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* @param {!Object.<string, !shaka.media.SegmentIndex>} segmentIndexMap
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* @param {boolean} isUpdate True if the manifest is being updated.
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* @throws shaka.util.Error When there is a parsing error.
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* @return {shaka.dash.DashParser.StreamInfo}
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*/
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static createStream(context, requestInitSegment, segmentIndexMap, isUpdate) {
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goog.asserts.assert(context.representation.segmentTemplate,
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'Should only be called with SegmentTemplate');
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const SegmentTemplate = shaka.dash.SegmentTemplate;
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const init = SegmentTemplate.createInitSegment_(context);
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const info = SegmentTemplate.parseSegmentTemplateInfo_(context);
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SegmentTemplate.checkSegmentTemplateInfo_(context, info);
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/** @type {?shaka.dash.DashParser.SegmentIndexFunctions} */
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let segmentIndexFunctions = null;
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if (info.indexTemplate) {
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segmentIndexFunctions = SegmentTemplate.createFromIndexTemplate_(
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context, requestInitSegment, init, info);
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} else if (info.segmentDuration) {
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if (!isUpdate) {
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context.presentationTimeline.notifyMaxSegmentDuration(
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info.segmentDuration);
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context.presentationTimeline.notifyMinSegmentStartTime(
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context.periodInfo.start);
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}
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segmentIndexFunctions =
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SegmentTemplate.createFromDuration_(context, info);
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} else {
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/** @type {shaka.media.SegmentIndex} */
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let segmentIndex = null;
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let id = null;
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if (context.period.id && context.representation.id) {
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// Only check/store the index if period and representation IDs are set.
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id = context.period.id + ',' + context.representation.id;
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segmentIndex = segmentIndexMap[id];
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}
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const references = SegmentTemplate.createFromTimeline_(context, info);
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// Don't fit live content, since it might receive more segments.
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// Unless that live content is multi-period; it's safe to fit every period
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// but the last one, since only the last period might receive new
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// segments.
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const shouldFit = !context.dynamic || !context.periodInfo.isLastPeriod;
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if (segmentIndex) {
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if (shouldFit) {
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// Fit the new references before merging them, so that the merge
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// algorithm has a more accurate view of their start and end times.
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const wrapper = new shaka.media.SegmentIndex(references);
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wrapper.fit(context.periodInfo.duration);
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}
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segmentIndex.merge(references);
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const start =
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context.presentationTimeline.getSegmentAvailabilityStart();
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segmentIndex.evict(start - context.periodInfo.start);
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} else {
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context.presentationTimeline.notifySegments(
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references, context.periodInfo.start);
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segmentIndex = new shaka.media.SegmentIndex(references);
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if (id && context.dynamic) {
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segmentIndexMap[id] = segmentIndex;
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}
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}
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if (shouldFit) {
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segmentIndex.fit(context.periodInfo.duration);
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}
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segmentIndexFunctions = {
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createSegmentIndex: () => Promise.resolve(),
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findSegmentPosition: (i) => segmentIndex.find(i),
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getSegmentReference: (i) => segmentIndex.get(i),
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};
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}
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return {
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createSegmentIndex: segmentIndexFunctions.createSegmentIndex,
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findSegmentPosition: segmentIndexFunctions.findSegmentPosition,
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getSegmentReference: segmentIndexFunctions.getSegmentReference,
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initSegmentReference: init,
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scaledPresentationTimeOffset: info.scaledPresentationTimeOffset,
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};
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}
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/**
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* @param {?shaka.dash.DashParser.InheritanceFrame} frame
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* @return {Element}
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* @private
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*/
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static fromInheritance_(frame) {
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return frame.segmentTemplate;
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}
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/**
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* Parses a SegmentTemplate element into an info object.
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*
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* @param {shaka.dash.DashParser.Context} context
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* @return {shaka.dash.SegmentTemplate.SegmentTemplateInfo}
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* @private
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*/
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static parseSegmentTemplateInfo_(context) {
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const SegmentTemplate = shaka.dash.SegmentTemplate;
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const MpdUtils = shaka.dash.MpdUtils;
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const segmentInfo =
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MpdUtils.parseSegmentInfo(context, SegmentTemplate.fromInheritance_);
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const media = MpdUtils.inheritAttribute(
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context, SegmentTemplate.fromInheritance_, 'media');
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const index = MpdUtils.inheritAttribute(
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context, SegmentTemplate.fromInheritance_, 'index');
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return {
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segmentDuration: segmentInfo.segmentDuration,
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timescale: segmentInfo.timescale,
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startNumber: segmentInfo.startNumber,
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scaledPresentationTimeOffset: segmentInfo.scaledPresentationTimeOffset,
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unscaledPresentationTimeOffset:
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segmentInfo.unscaledPresentationTimeOffset,
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timeline: segmentInfo.timeline,
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mediaTemplate: media,
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indexTemplate: index,
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};
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}
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/**
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* Verifies a SegmentTemplate info object.
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*
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* @param {shaka.dash.DashParser.Context} context
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* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
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* @throws shaka.util.Error When there is a parsing error.
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* @private
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*/
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static checkSegmentTemplateInfo_(context, info) {
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let n = 0;
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n += info.indexTemplate ? 1 : 0;
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n += info.timeline ? 1 : 0;
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n += info.segmentDuration ? 1 : 0;
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if (n == 0) {
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shaka.log.error(
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'SegmentTemplate does not contain any segment information:',
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'the SegmentTemplate must contain either an index URL template',
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'a SegmentTimeline, or a segment duration.',
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context.representation);
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throw new shaka.util.Error(
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shaka.util.Error.Severity.CRITICAL,
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shaka.util.Error.Category.MANIFEST,
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shaka.util.Error.Code.DASH_NO_SEGMENT_INFO);
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} else if (n != 1) {
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shaka.log.warning(
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'SegmentTemplate containes multiple segment information sources:',
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'the SegmentTemplate should only contain an index URL template,',
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'a SegmentTimeline or a segment duration.',
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context.representation);
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if (info.indexTemplate) {
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shaka.log.info('Using the index URL template by default.');
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info.timeline = null;
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info.segmentDuration = null;
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} else {
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goog.asserts.assert(info.timeline, 'There should be a timeline');
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shaka.log.info('Using the SegmentTimeline by default.');
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info.segmentDuration = null;
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}
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}
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if (!info.indexTemplate && !info.mediaTemplate) {
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shaka.log.error(
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'SegmentTemplate does not contain sufficient segment information:',
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'the SegmentTemplate\'s media URL template is missing.',
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context.representation);
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throw new shaka.util.Error(
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shaka.util.Error.Severity.CRITICAL,
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shaka.util.Error.Category.MANIFEST,
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shaka.util.Error.Code.DASH_NO_SEGMENT_INFO);
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}
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}
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/**
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* Creates segment index functions from a index URL template.
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*
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* @param {shaka.dash.DashParser.Context} context
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* @param {shaka.dash.DashParser.RequestInitSegmentCallback}
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* requestInitSegment
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* @param {shaka.media.InitSegmentReference} init
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* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
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* @throws shaka.util.Error When there is a parsing error.
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* @return {shaka.dash.DashParser.SegmentIndexFunctions}
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* @private
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*/
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static createFromIndexTemplate_(context, requestInitSegment, init, info) {
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const MpdUtils = shaka.dash.MpdUtils;
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const ManifestParserUtils = shaka.util.ManifestParserUtils;
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// Determine the container type.
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const containerType = context.representation.mimeType.split('/')[1];
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if ((containerType != 'mp4') && (containerType != 'webm')) {
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shaka.log.error(
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'SegmentTemplate specifies an unsupported container type.',
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context.representation);
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throw new shaka.util.Error(
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shaka.util.Error.Severity.CRITICAL,
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shaka.util.Error.Category.MANIFEST,
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shaka.util.Error.Code.DASH_UNSUPPORTED_CONTAINER);
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}
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if ((containerType == 'webm') && !init) {
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shaka.log.error(
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'SegmentTemplate does not contain sufficient segment information:',
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'the SegmentTemplate uses a WebM container,',
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'but does not contain an initialization URL template.',
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context.representation);
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throw new shaka.util.Error(
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shaka.util.Error.Severity.CRITICAL,
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shaka.util.Error.Category.MANIFEST,
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shaka.util.Error.Code.DASH_WEBM_MISSING_INIT);
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}
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goog.asserts.assert(info.indexTemplate, 'must be using index template');
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const filledTemplate = MpdUtils.fillUriTemplate(
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info.indexTemplate, context.representation.id,
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null, context.bandwidth || null, null);
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const resolvedUris = ManifestParserUtils.resolveUris(
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context.representation.baseUris, [filledTemplate]);
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return shaka.dash.SegmentBase.createSegmentIndexFromUris(
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context, requestInitSegment, init, resolvedUris, 0, null, containerType,
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info.scaledPresentationTimeOffset);
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}
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/**
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* Creates segment index functions from a segment duration.
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*
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* @param {shaka.dash.DashParser.Context} context
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* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
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* @return {shaka.dash.DashParser.SegmentIndexFunctions}
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* @private
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*/
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static createFromDuration_(context, info) {
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goog.asserts.assert(info.mediaTemplate,
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'There should be a media template with duration');
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const MpdUtils = shaka.dash.MpdUtils;
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const ManifestParserUtils = shaka.util.ManifestParserUtils;
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const periodDuration = context.periodInfo.duration;
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const segmentDuration = info.segmentDuration;
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const startNumber = info.startNumber;
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const timescale = info.timescale;
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const template = info.mediaTemplate;
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const bandwidth = context.bandwidth || null;
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const id = context.representation.id;
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const baseUris = context.representation.baseUris;
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const find = (periodTime) => {
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if (periodTime < 0) {
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return null;
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} else if (periodDuration && periodTime >= periodDuration) {
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return null;
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}
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return Math.floor(periodTime / segmentDuration);
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};
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const get = (position) => {
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const segmentStart = position * segmentDuration;
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// Cap the segment end at the period end, to avoid period transition
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// issues in StreamingEngine.
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let segmentEnd = segmentStart + segmentDuration;
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if (periodDuration) {
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segmentEnd = Math.min(segmentEnd, periodDuration);
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}
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// Do not construct segments references that should not exist.
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if (segmentEnd < 0) {
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return null;
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} else if (periodDuration && segmentStart >= periodDuration) {
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return null;
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}
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const getUris = () => {
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const mediaUri = MpdUtils.fillUriTemplate(
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template, id, position + startNumber, bandwidth,
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segmentStart * timescale);
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return ManifestParserUtils.resolveUris(baseUris, [mediaUri]);
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};
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return new shaka.media.SegmentReference(
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position, segmentStart, segmentEnd, getUris, 0, null);
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};
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return {
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createSegmentIndex: () => Promise.resolve(),
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findSegmentPosition: find,
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getSegmentReference: get,
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};
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}
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/**
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* Creates segment references from a timeline.
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*
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* @param {shaka.dash.DashParser.Context} context
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* @param {shaka.dash.SegmentTemplate.SegmentTemplateInfo} info
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* @return {!Array.<!shaka.media.SegmentReference>}
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* @private
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*/
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static createFromTimeline_(context, info) {
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const MpdUtils = shaka.dash.MpdUtils;
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const ManifestParserUtils = shaka.util.ManifestParserUtils;
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/** @type {!Array.<!shaka.media.SegmentReference>} */
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const references = [];
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const enum_ = (it) => shaka.util.Iterables.enumerate(it);
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for (const {i, item: {start, unscaledStart, end}} of enum_(info.timeline)) {
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// Note: i = k - 1, where k indicates the k'th segment listed in the MPD.
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// (See section 5.3.9.5.3 of the DASH spec.)
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const segmentReplacement = i + info.startNumber;
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// Consider the presentation time offset in segment uri computation
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const timeReplacement = unscaledStart +
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info.unscaledPresentationTimeOffset;
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const createUris =
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() => {
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goog.asserts.assert(
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info.mediaTemplate,
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'There should be a media template with a timeline');
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const mediaUri = MpdUtils.fillUriTemplate(
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info.mediaTemplate, context.representation.id,
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segmentReplacement, context.bandwidth || null, timeReplacement);
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return ManifestParserUtils
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.resolveUris(context.representation.baseUris, [mediaUri])
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.map((g) => {
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return g.toString();
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});
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};
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references.push(new shaka.media.SegmentReference(
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segmentReplacement, start, end, createUris, 0, null));
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}
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return references;
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}
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/**
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* Creates an init segment reference from a context object.
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*
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* @param {shaka.dash.DashParser.Context} context
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* @return {shaka.media.InitSegmentReference}
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* @private
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*/
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static createInitSegment_(context) {
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const MpdUtils = shaka.dash.MpdUtils;
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const ManifestParserUtils = shaka.util.ManifestParserUtils;
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const SegmentTemplate = shaka.dash.SegmentTemplate;
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const initialization = MpdUtils.inheritAttribute(
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context, SegmentTemplate.fromInheritance_, 'initialization');
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if (!initialization) {
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return null;
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}
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const repId = context.representation.id;
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const bandwidth = context.bandwidth || null;
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const baseUris = context.representation.baseUris;
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const getUris = () => {
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goog.asserts.assert(initialization, 'Should have returned earler');
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const filledTemplate = MpdUtils.fillUriTemplate(
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initialization, repId, null, bandwidth, null);
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const resolvedUris = ManifestParserUtils.resolveUris(
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baseUris, [filledTemplate]);
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return resolvedUris;
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};
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return new shaka.media.InitSegmentReference(getUris, 0, null);
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}
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};
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/**
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* @typedef {{
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* timescale: number,
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* segmentDuration: ?number,
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* startNumber: number,
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* scaledPresentationTimeOffset: number,
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* unscaledPresentationTimeOffset: number,
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* timeline: Array.<shaka.dash.MpdUtils.TimeRange>,
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* mediaTemplate: ?string,
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* indexTemplate: ?string
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* }}
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* @private
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*
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* @description
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* Contains information about a SegmentTemplate.
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*
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* @property {number} timescale
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* The time-scale of the representation.
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* @property {?number} segmentDuration
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* The duration of the segments in seconds, if given.
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* @property {number} startNumber
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* The start number of the segments; 1 or greater.
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* @property {number} scaledPresentationTimeOffset
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* The presentation time offset of the representation, in seconds.
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* @property {number} unscaledPresentationTimeOffset
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* The presentation time offset of the representation, in timescale units.
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* @property {Array.<shaka.dash.MpdUtils.TimeRange>} timeline
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* The timeline of the representation, if given. Times in seconds.
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* @property {?string} mediaTemplate
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* The media URI template, if given.
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* @property {?string} indexTemplate
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* The index URI template, if given.
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*/
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shaka.dash.SegmentTemplate.SegmentTemplateInfo;
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