Source: lib/dash/segment_base.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.dash.SegmentBase');
  9. goog.require('goog.asserts');
  10. goog.require('shaka.dash.MpdUtils');
  11. goog.require('shaka.log');
  12. goog.require('shaka.media.InitSegmentReference');
  13. goog.require('shaka.media.Mp4SegmentIndexParser');
  14. goog.require('shaka.media.SegmentIndex');
  15. goog.require('shaka.media.WebmSegmentIndexParser');
  16. goog.require('shaka.util.Error');
  17. goog.require('shaka.util.ManifestParserUtils');
  18. goog.require('shaka.util.ObjectUtils');
  19. goog.require('shaka.util.StringUtils');
  20. goog.require('shaka.util.TXml');
  21. goog.requireType('shaka.dash.DashParser');
  22. goog.requireType('shaka.media.PresentationTimeline');
  23. goog.requireType('shaka.media.SegmentReference');
  26. /**
  27.  * @summary A set of functions for parsing SegmentBase elements.
  28.  */
  29. shaka.dash.SegmentBase = class {
  30.   /**
  31.    * Creates an init segment reference from a Context object.
  32.    *
  33.    * @param {shaka.dash.DashParser.Context} context
  34.    * @param {function(?shaka.dash.DashParser.InheritanceFrame):
  35.    *    ?shaka.extern.xml.Node} callback
  36.    * @param {shaka.extern.aesKey|undefined} aesKey
  37.    * @return {shaka.media.InitSegmentReference}
  38.    */
  39.   static createInitSegment(context, callback, aesKey) {
  40.     const MpdUtils = shaka.dash.MpdUtils;
  41.     const TXml = shaka.util.TXml;
  42.     const ManifestParserUtils = shaka.util.ManifestParserUtils;
  43.     const StringUtils = shaka.util.StringUtils;
  45.     const initialization =
  46.         MpdUtils.inheritChild(context, callback, 'Initialization');
  47.     if (!initialization) {
  48.       return null;
  49.     }
  51.     let resolvedUris = context.representation.getBaseUris();
  52.     const uri = initialization.attributes['sourceURL'];
  53.     if (uri) {
  54.       resolvedUris = ManifestParserUtils.resolveUris(resolvedUris, [
  55.         StringUtils.htmlUnescape(uri),
  56.       ]);
  57.     }
  59.     let startByte = 0;
  60.     let endByte = null;
  61.     const range = TXml.parseAttr(initialization, 'range', TXml.parseRange);
  62.     if (range) {
  63.       startByte = range.start;
  64.       endByte = range.end;
  65.     }
  67.     const getUris = () => resolvedUris;
  68.     const qualityInfo = shaka.dash.SegmentBase.createQualityInfo(context);
  69.     const ref = new shaka.media.InitSegmentReference(
  70.         getUris,
  71.         startByte,
  72.         endByte,
  73.         qualityInfo,
  74.         /* timescale= */ null,
  75.         /* segmentData= */ null,
  76.         aesKey);
  77.     ref.codecs = context.representation.codecs;
  78.     ref.mimeType = context.representation.mimeType;
  79.     return ref;
  80.   }
  82.   /**
  83.    * Creates a new StreamInfo object.
  84.    *
  85.    * @param {shaka.dash.DashParser.Context} context
  86.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  87.    * @param {shaka.extern.aesKey|undefined} aesKey
  88.    * @return {shaka.dash.DashParser.StreamInfo}
  89.    */
  90.   static createStreamInfo(context, requestSegment, aesKey) {
  91.     goog.asserts.assert(context.representation.segmentBase,
  92.         'Should only be called with SegmentBase');
  93.     // Since SegmentBase does not need updates, simply treat any call as
  94.     // the initial parse.
  95.     const MpdUtils = shaka.dash.MpdUtils;
  96.     const SegmentBase = shaka.dash.SegmentBase;
  97.     const TXml = shaka.util.TXml;
  99.     const unscaledPresentationTimeOffset = Number(MpdUtils.inheritAttribute(
  100.         context, SegmentBase.fromInheritance_, 'presentationTimeOffset')) || 0;
  102.     const timescaleStr = MpdUtils.inheritAttribute(
  103.         context, SegmentBase.fromInheritance_, 'timescale');
  104.     let timescale = 1;
  105.     if (timescaleStr) {
  106.       timescale = TXml.parsePositiveInt(timescaleStr) || 1;
  107.     }
  109.     const scaledPresentationTimeOffset =
  110.         (unscaledPresentationTimeOffset / timescale) || 0;
  112.     const initSegmentReference = SegmentBase.createInitSegment(
  113.         context, SegmentBase.fromInheritance_, aesKey);
  115.     // Throws an immediate error if the format is unsupported.
  116.     SegmentBase.checkSegmentIndexRangeSupport_(context, initSegmentReference);
  118.     // Direct fields of context will be reassigned by the parser before
  119.     // generateSegmentIndex is called.  So we must make a shallow copy first,
  120.     // and use that in the generateSegmentIndex callbacks.
  121.     const shallowCopyOfContext =
  122.         shaka.util.ObjectUtils.shallowCloneObject(context);
  124.     return {
  125.       generateSegmentIndex: () => {
  126.         return SegmentBase.generateSegmentIndex_(
  127.             shallowCopyOfContext, requestSegment, initSegmentReference,
  128.             scaledPresentationTimeOffset);
  129.       },
  130.     };
  131.   }
  133.   /**
  134.    * Creates a SegmentIndex for the given URIs and context.
  135.    *
  136.    * @param {shaka.dash.DashParser.Context} context
  137.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  138.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  139.    * @param {!Array.<string>} uris
  140.    * @param {number} startByte
  141.    * @param {?number} endByte
  142.    * @param {number} scaledPresentationTimeOffset
  143.    * @return {!Promise.<shaka.media.SegmentIndex>}
  144.    */
  145.   static async generateSegmentIndexFromUris(
  146.       context, requestSegment, initSegmentReference, uris, startByte,
  147.       endByte, scaledPresentationTimeOffset) {
  148.     // Unpack context right away, before we start an async process.
  149.     // This immunizes us against changes to the context object later.
  150.     /** @type {shaka.media.PresentationTimeline} */
  151.     const presentationTimeline = context.presentationTimeline;
  152.     const fitLast = !context.dynamic || !context.periodInfo.isLastPeriod;
  153.     const periodStart = context.periodInfo.start;
  154.     const periodDuration = context.periodInfo.duration;
  155.     const containerType = context.representation.mimeType.split('/')[1];
  157.     // Create a local variable to bind to so we can set to null to help the GC.
  158.     let localRequest = requestSegment;
  159.     let segmentIndex = null;
  161.     const responses = [
  162.       localRequest(uris, startByte, endByte, /* isInit= */ false),
  163.       containerType == 'webm' ?
  164.           localRequest(
  165.               initSegmentReference.getUris(),
  166.               initSegmentReference.startByte,
  167.               initSegmentReference.endByte,
  168.               /* isInit= */ true) :
  169.           null,
  170.     ];
  172.     localRequest = null;
  173.     const results = await Promise.all(responses);
  174.     const indexData = results[0];
  175.     const initData = results[1] || null;
  176.     /** @type {Array.<!shaka.media.SegmentReference>} */
  177.     let references = null;
  179.     const timestampOffset = periodStart - scaledPresentationTimeOffset;
  180.     const appendWindowStart = periodStart;
  181.     const appendWindowEnd = periodDuration ?
  182.         periodStart + periodDuration : Infinity;
  184.     if (containerType == 'mp4') {
  185.       references = shaka.media.Mp4SegmentIndexParser.parse(
  186.           indexData, startByte, uris, initSegmentReference, timestampOffset,
  187.           appendWindowStart, appendWindowEnd);
  188.     } else {
  189.       goog.asserts.assert(initData, 'WebM requires init data');
  190.       references = shaka.media.WebmSegmentIndexParser.parse(
  191.           indexData, initData, uris, initSegmentReference, timestampOffset,
  192.           appendWindowStart, appendWindowEnd);
  193.     }
  194.     for (const ref of references) {
  195.       ref.codecs = context.representation.codecs;
  196.       ref.mimeType = context.representation.mimeType;
  197.     }
  199.     presentationTimeline.notifySegments(references);
  201.     // Since containers are never updated, we don't need to store the
  202.     // segmentIndex in the map.
  203.     goog.asserts.assert(!segmentIndex,
  204.         'Should not call generateSegmentIndex twice');
  206.     segmentIndex = new shaka.media.SegmentIndex(references);
  207.     if (fitLast) {
  208.       segmentIndex.fit(appendWindowStart, appendWindowEnd, /* isNew= */ true);
  209.     }
  210.     return segmentIndex;
  211.   }
  213.   /**
  214.    * @param {?shaka.dash.DashParser.InheritanceFrame} frame
  215.    * @return {?shaka.extern.xml.Node}
  216.    * @private
  217.    */
  218.   static fromInheritance_(frame) {
  219.     return frame.segmentBase;
  220.   }
  222.   /**
  223.    * Compute the byte range of the segment index from the container.
  224.    *
  225.    * @param {shaka.dash.DashParser.Context} context
  226.    * @return {?{start: number, end: number}}
  227.    * @private
  228.    */
  229.   static computeIndexRange_(context) {
  230.     const MpdUtils = shaka.dash.MpdUtils;
  231.     const SegmentBase = shaka.dash.SegmentBase;
  232.     const TXml = shaka.util.TXml;
  234.     const representationIndex = MpdUtils.inheritChild(
  235.         context, SegmentBase.fromInheritance_, 'RepresentationIndex');
  236.     const indexRangeElem = MpdUtils.inheritAttribute(
  237.         context, SegmentBase.fromInheritance_, 'indexRange');
  239.     let indexRange = TXml.parseRange(indexRangeElem || '');
  240.     if (representationIndex) {
  241.       indexRange = TXml.parseAttr(
  242.           representationIndex, 'range', TXml.parseRange, indexRange);
  243.     }
  244.     return indexRange;
  245.   }
  247.   /**
  248.    * Compute the URIs of the segment index from the container.
  249.    *
  250.    * @param {shaka.dash.DashParser.Context} context
  251.    * @return {!Array.<string>}
  252.    * @private
  253.    */
  254.   static computeIndexUris_(context) {
  255.     const ManifestParserUtils = shaka.util.ManifestParserUtils;
  256.     const MpdUtils = shaka.dash.MpdUtils;
  257.     const SegmentBase = shaka.dash.SegmentBase;
  258.     const StringUtils = shaka.util.StringUtils;
  260.     const representationIndex = MpdUtils.inheritChild(
  261.         context, SegmentBase.fromInheritance_, 'RepresentationIndex');
  263.     let indexUris = context.representation.getBaseUris();
  264.     if (representationIndex) {
  265.       const representationUri =
  266.         StringUtils.htmlUnescape(representationIndex.attributes['sourceURL']);
  267.       if (representationUri) {
  268.         indexUris = ManifestParserUtils.resolveUris(
  269.             indexUris, [representationUri]);
  270.       }
  271.     }
  273.     return indexUris;
  274.   }
  276.   /**
  277.    * Check if this type of segment index is supported.  This allows for
  278.    * immediate errors during parsing, as opposed to an async error from
  279.    * createSegmentIndex().
  280.    *
  281.    * Also checks for a valid byte range, which is not required for callers from
  282.    * SegmentTemplate.
  283.    *
  284.    * @param {shaka.dash.DashParser.Context} context
  285.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  286.    * @private
  287.    */
  288.   static checkSegmentIndexRangeSupport_(context, initSegmentReference) {
  289.     const SegmentBase = shaka.dash.SegmentBase;
  291.     SegmentBase.checkSegmentIndexSupport(context, initSegmentReference);
  293.     const indexRange = SegmentBase.computeIndexRange_(context);
  294.     if (!indexRange) {
  295.       shaka.log.error(
  296.           'SegmentBase does not contain sufficient segment information:',
  297.           'the SegmentBase does not contain @indexRange',
  298.           'or a RepresentationIndex element.',
  299.           context.representation);
  300.       throw new shaka.util.Error(
  301.           shaka.util.Error.Severity.CRITICAL,
  302.           shaka.util.Error.Category.MANIFEST,
  303.           shaka.util.Error.Code.DASH_NO_SEGMENT_INFO);
  304.     }
  305.   }
  307.   /**
  308.    * Check if this type of segment index is supported.  This allows for
  309.    * immediate errors during parsing, as opposed to an async error from
  310.    * createSegmentIndex().
  311.    *
  312.    * @param {shaka.dash.DashParser.Context} context
  313.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  314.    */
  315.   static checkSegmentIndexSupport(context, initSegmentReference) {
  316.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  318.     const contentType = context.representation.contentType;
  319.     const containerType = context.representation.mimeType.split('/')[1];
  321.     if (contentType != ContentType.TEXT && containerType != 'mp4' &&
  322.         containerType != 'webm') {
  323.       shaka.log.error(
  324.           'SegmentBase specifies an unsupported container type.',
  325.           context.representation);
  326.       throw new shaka.util.Error(
  327.           shaka.util.Error.Severity.CRITICAL,
  328.           shaka.util.Error.Category.MANIFEST,
  329.           shaka.util.Error.Code.DASH_UNSUPPORTED_CONTAINER);
  330.     }
  332.     if ((containerType == 'webm') && !initSegmentReference) {
  333.       shaka.log.error(
  334.           'SegmentBase does not contain sufficient segment information:',
  335.           'the SegmentBase uses a WebM container,',
  336.           'but does not contain an Initialization element.',
  337.           context.representation);
  338.       throw new shaka.util.Error(
  339.           shaka.util.Error.Severity.CRITICAL,
  340.           shaka.util.Error.Category.MANIFEST,
  341.           shaka.util.Error.Code.DASH_WEBM_MISSING_INIT);
  342.     }
  343.   }
  345.   /**
  346.    * Generate a SegmentIndex from a Context object.
  347.    *
  348.    * @param {shaka.dash.DashParser.Context} context
  349.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  350.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  351.    * @param {number} scaledPresentationTimeOffset
  352.    * @return {!Promise.<shaka.media.SegmentIndex>}
  353.    * @private
  354.    */
  355.   static generateSegmentIndex_(
  356.       context, requestSegment, initSegmentReference,
  357.       scaledPresentationTimeOffset) {
  358.     const SegmentBase = shaka.dash.SegmentBase;
  360.     const indexUris = SegmentBase.computeIndexUris_(context);
  361.     const indexRange = SegmentBase.computeIndexRange_(context);
  362.     goog.asserts.assert(indexRange, 'Index range should not be null!');
  364.     return shaka.dash.SegmentBase.generateSegmentIndexFromUris(
  365.         context, requestSegment, initSegmentReference, indexUris,
  366.         indexRange.start, indexRange.end,
  367.         scaledPresentationTimeOffset);
  368.   }
  370.   /**
  371.    * Create a MediaQualityInfo object from a Context object.
  372.    *
  373.    * @param {!shaka.dash.DashParser.Context} context
  374.    * @return {!shaka.extern.MediaQualityInfo}
  375.    */
  376.   static createQualityInfo(context) {
  377.     const representation = context.representation;
  378.     return {
  379.       bandwidth: context.bandwidth,
  380.       audioSamplingRate: representation.audioSamplingRate,
  381.       codecs: representation.codecs,
  382.       contentType: representation.contentType,
  383.       frameRate: representation.frameRate || null,
  384.       height: representation.height || null,
  385.       mimeType: representation.mimeType,
  386.       channelsCount: representation.numChannels,
  387.       pixelAspectRatio: representation.pixelAspectRatio || null,
  388.       width: representation.width || null,
  389.     };
  390.   }
  391. };