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.Mp4SegmentIndexParser');
  11. goog.require('shaka.dash.MpdUtils');
  12. goog.require('shaka.dash.WebmSegmentIndexParser');
  13. goog.require('shaka.log');
  14. goog.require('shaka.media.InitSegmentReference');
  15. goog.require('shaka.media.SegmentIndex');
  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.       ], context.urlParams());
  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 encrypted = context.adaptationSet.encrypted;
  70.     const ref = new shaka.media.InitSegmentReference(
  71.         getUris,
  72.         startByte,
  73.         endByte,
  74.         qualityInfo,
  75.         /* timescale= */ null,
  76.         /* segmentData= */ null,
  77.         aesKey,
  78.         encrypted);
  79.     ref.codecs = context.representation.codecs;
  80.     ref.mimeType = context.representation.mimeType;
  81.     return ref;
  82.   }
  84.   /**
  85.    * Creates a new StreamInfo object.
  86.    *
  87.    * @param {shaka.dash.DashParser.Context} context
  88.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  89.    * @param {shaka.extern.aesKey|undefined} aesKey
  90.    * @return {shaka.dash.DashParser.StreamInfo}
  91.    */
  92.   static createStreamInfo(context, requestSegment, aesKey) {
  93.     goog.asserts.assert(context.representation.segmentBase,
  94.         'Should only be called with SegmentBase');
  95.     // Since SegmentBase does not need updates, simply treat any call as
  96.     // the initial parse.
  97.     const MpdUtils = shaka.dash.MpdUtils;
  98.     const SegmentBase = shaka.dash.SegmentBase;
  99.     const TXml = shaka.util.TXml;
  101.     const unscaledPresentationTimeOffset = Number(MpdUtils.inheritAttribute(
  102.         context, SegmentBase.fromInheritance_, 'presentationTimeOffset')) || 0;
  104.     const timescaleStr = MpdUtils.inheritAttribute(
  105.         context, SegmentBase.fromInheritance_, 'timescale');
  106.     let timescale = 1;
  107.     if (timescaleStr) {
  108.       timescale = TXml.parsePositiveInt(timescaleStr) || 1;
  109.     }
  111.     const scaledPresentationTimeOffset =
  112.         (unscaledPresentationTimeOffset / timescale) || 0;
  114.     const initSegmentReference = SegmentBase.createInitSegment(
  115.         context, SegmentBase.fromInheritance_, aesKey);
  117.     // Throws an immediate error if the format is unsupported.
  118.     SegmentBase.checkSegmentIndexRangeSupport_(context, initSegmentReference);
  120.     // Direct fields of context will be reassigned by the parser before
  121.     // generateSegmentIndex is called.  So we must make a shallow copy first,
  122.     // and use that in the generateSegmentIndex callbacks.
  123.     const shallowCopyOfContext =
  124.         shaka.util.ObjectUtils.shallowCloneObject(context);
  126.     return {
  127.       generateSegmentIndex: () => {
  128.         return SegmentBase.generateSegmentIndex_(
  129.             shallowCopyOfContext, requestSegment, initSegmentReference,
  130.             scaledPresentationTimeOffset);
  131.       },
  132.     };
  133.   }
  135.   /**
  136.    * Creates a SegmentIndex for the given URIs and context.
  137.    *
  138.    * @param {shaka.dash.DashParser.Context} context
  139.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  140.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  141.    * @param {!Array<string>} uris
  142.    * @param {number} startByte
  143.    * @param {?number} endByte
  144.    * @param {number} scaledPresentationTimeOffset
  145.    * @return {!Promise<shaka.media.SegmentIndex>}
  146.    */
  147.   static async generateSegmentIndexFromUris(
  148.       context, requestSegment, initSegmentReference, uris, startByte,
  149.       endByte, scaledPresentationTimeOffset) {
  150.     // Unpack context right away, before we start an async process.
  151.     // This immunizes us against changes to the context object later.
  152.     /** @type {shaka.media.PresentationTimeline} */
  153.     const presentationTimeline = context.presentationTimeline;
  154.     const fitLast = !context.dynamic || !context.periodInfo.isLastPeriod;
  155.     const periodStart = context.periodInfo.start;
  156.     const periodDuration = context.periodInfo.duration;
  157.     const containerType = context.representation.mimeType.split('/')[1];
  159.     // Create a local variable to bind to so we can set to null to help the GC.
  160.     let localRequest = requestSegment;
  161.     let segmentIndex = null;
  163.     const responses = [
  164.       localRequest(uris, startByte, endByte, /* isInit= */ false),
  165.       containerType == 'webm' ?
  166.           localRequest(
  167.               initSegmentReference.getUris(),
  168.               initSegmentReference.startByte,
  169.               initSegmentReference.endByte,
  170.               /* isInit= */ true) :
  171.           null,
  172.     ];
  174.     localRequest = null;
  175.     const results = await Promise.all(responses);
  176.     const indexData = results[0];
  177.     const initData = results[1] || null;
  178.     /** @type {Array<!shaka.media.SegmentReference>} */
  179.     let references = null;
  181.     const timestampOffset = periodStart - scaledPresentationTimeOffset;
  182.     const appendWindowStart = periodStart;
  183.     const appendWindowEnd = periodDuration ?
  184.         periodStart + periodDuration : Infinity;
  186.     if (containerType == 'mp4') {
  187.       references = shaka.dash.Mp4SegmentIndexParser.parse(
  188.           indexData, startByte, uris, initSegmentReference, timestampOffset,
  189.           appendWindowStart, appendWindowEnd);
  190.     } else {
  191.       goog.asserts.assert(initData, 'WebM requires init data');
  192.       references = shaka.dash.WebmSegmentIndexParser.parse(
  193.           indexData, initData, uris, initSegmentReference, timestampOffset,
  194.           appendWindowStart, appendWindowEnd);
  195.     }
  196.     for (const ref of references) {
  197.       ref.codecs = context.representation.codecs;
  198.       ref.mimeType = context.representation.mimeType;
  199.       ref.bandwidth = context.bandwidth;
  200.     }
  202.     presentationTimeline.notifySegments(references);
  204.     // Since containers are never updated, we don't need to store the
  205.     // segmentIndex in the map.
  206.     goog.asserts.assert(!segmentIndex,
  207.         'Should not call generateSegmentIndex twice');
  209.     segmentIndex = new shaka.media.SegmentIndex(references);
  210.     if (fitLast) {
  211.       segmentIndex.fit(appendWindowStart, appendWindowEnd, /* isNew= */ true);
  212.     }
  213.     return segmentIndex;
  214.   }
  216.   /**
  217.    * @param {?shaka.dash.DashParser.InheritanceFrame} frame
  218.    * @return {?shaka.extern.xml.Node}
  219.    * @private
  220.    */
  221.   static fromInheritance_(frame) {
  222.     return frame.segmentBase;
  223.   }
  225.   /**
  226.    * Compute the byte range of the segment index from the container.
  227.    *
  228.    * @param {shaka.dash.DashParser.Context} context
  229.    * @return {?{start: number, end: number}}
  230.    * @private
  231.    */
  232.   static computeIndexRange_(context) {
  233.     const MpdUtils = shaka.dash.MpdUtils;
  234.     const SegmentBase = shaka.dash.SegmentBase;
  235.     const TXml = shaka.util.TXml;
  237.     const representationIndex = MpdUtils.inheritChild(
  238.         context, SegmentBase.fromInheritance_, 'RepresentationIndex');
  239.     const indexRangeElem = MpdUtils.inheritAttribute(
  240.         context, SegmentBase.fromInheritance_, 'indexRange');
  242.     let indexRange = TXml.parseRange(indexRangeElem || '');
  243.     if (representationIndex) {
  244.       indexRange = TXml.parseAttr(
  245.           representationIndex, 'range', TXml.parseRange, indexRange);
  246.     }
  247.     return indexRange;
  248.   }
  250.   /**
  251.    * Compute the URIs of the segment index from the container.
  252.    *
  253.    * @param {shaka.dash.DashParser.Context} context
  254.    * @return {!Array<string>}
  255.    * @private
  256.    */
  257.   static computeIndexUris_(context) {
  258.     const ManifestParserUtils = shaka.util.ManifestParserUtils;
  259.     const MpdUtils = shaka.dash.MpdUtils;
  260.     const SegmentBase = shaka.dash.SegmentBase;
  261.     const StringUtils = shaka.util.StringUtils;
  263.     const representationIndex = MpdUtils.inheritChild(
  264.         context, SegmentBase.fromInheritance_, 'RepresentationIndex');
  266.     let indexUris = context.representation.getBaseUris();
  267.     if (representationIndex) {
  268.       const representationUri =
  269.         StringUtils.htmlUnescape(representationIndex.attributes['sourceURL']);
  270.       if (representationUri) {
  271.         indexUris = ManifestParserUtils.resolveUris(
  272.             indexUris, [representationUri], context.urlParams());
  273.       }
  274.     }
  276.     return indexUris;
  277.   }
  279.   /**
  280.    * Check if this type of segment index is supported.  This allows for
  281.    * immediate errors during parsing, as opposed to an async error from
  282.    * createSegmentIndex().
  283.    *
  284.    * Also checks for a valid byte range, which is not required for callers from
  285.    * SegmentTemplate.
  286.    *
  287.    * @param {shaka.dash.DashParser.Context} context
  288.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  289.    * @private
  290.    */
  291.   static checkSegmentIndexRangeSupport_(context, initSegmentReference) {
  292.     const SegmentBase = shaka.dash.SegmentBase;
  294.     SegmentBase.checkSegmentIndexSupport(context, initSegmentReference);
  296.     const indexRange = SegmentBase.computeIndexRange_(context);
  297.     if (!indexRange) {
  298.       shaka.log.error(
  299.           'SegmentBase does not contain sufficient segment information:',
  300.           'the SegmentBase does not contain @indexRange',
  301.           'or a RepresentationIndex element.',
  302.           context.representation);
  303.       throw new shaka.util.Error(
  304.           shaka.util.Error.Severity.CRITICAL,
  305.           shaka.util.Error.Category.MANIFEST,
  306.           shaka.util.Error.Code.DASH_NO_SEGMENT_INFO);
  307.     }
  308.   }
  310.   /**
  311.    * Check if this type of segment index is supported.  This allows for
  312.    * immediate errors during parsing, as opposed to an async error from
  313.    * createSegmentIndex().
  314.    *
  315.    * @param {shaka.dash.DashParser.Context} context
  316.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  317.    */
  318.   static checkSegmentIndexSupport(context, initSegmentReference) {
  319.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  321.     const contentType = context.representation.contentType;
  322.     const containerType = context.representation.mimeType.split('/')[1];
  324.     if (contentType != ContentType.TEXT && containerType != 'mp4' &&
  325.         containerType != 'webm') {
  326.       shaka.log.error(
  327.           'SegmentBase specifies an unsupported container type.',
  328.           context.representation);
  329.       throw new shaka.util.Error(
  330.           shaka.util.Error.Severity.CRITICAL,
  331.           shaka.util.Error.Category.MANIFEST,
  332.           shaka.util.Error.Code.DASH_UNSUPPORTED_CONTAINER);
  333.     }
  335.     if ((containerType == 'webm') && !initSegmentReference) {
  336.       shaka.log.error(
  337.           'SegmentBase does not contain sufficient segment information:',
  338.           'the SegmentBase uses a WebM container,',
  339.           'but does not contain an Initialization element.',
  340.           context.representation);
  341.       throw new shaka.util.Error(
  342.           shaka.util.Error.Severity.CRITICAL,
  343.           shaka.util.Error.Category.MANIFEST,
  344.           shaka.util.Error.Code.DASH_WEBM_MISSING_INIT);
  345.     }
  346.   }
  348.   /**
  349.    * Generate a SegmentIndex from a Context object.
  350.    *
  351.    * @param {shaka.dash.DashParser.Context} context
  352.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  353.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  354.    * @param {number} scaledPresentationTimeOffset
  355.    * @return {!Promise<shaka.media.SegmentIndex>}
  356.    * @private
  357.    */
  358.   static generateSegmentIndex_(
  359.       context, requestSegment, initSegmentReference,
  360.       scaledPresentationTimeOffset) {
  361.     const SegmentBase = shaka.dash.SegmentBase;
  363.     const indexUris = SegmentBase.computeIndexUris_(context);
  364.     const indexRange = SegmentBase.computeIndexRange_(context);
  365.     goog.asserts.assert(indexRange, 'Index range should not be null!');
  367.     return shaka.dash.SegmentBase.generateSegmentIndexFromUris(
  368.         context, requestSegment, initSegmentReference, indexUris,
  369.         indexRange.start, indexRange.end,
  370.         scaledPresentationTimeOffset);
  371.   }
  373.   /**
  374.    * Create a MediaQualityInfo object from a Context object.
  375.    *
  376.    * @param {!shaka.dash.DashParser.Context} context
  377.    * @return {!shaka.extern.MediaQualityInfo}
  378.    */
  379.   static createQualityInfo(context) {
  380.     const representation = context.representation;
  381.     return {
  382.       bandwidth: context.bandwidth,
  383.       audioSamplingRate: representation.audioSamplingRate,
  384.       codecs: representation.codecs,
  385.       contentType: representation.contentType,
  386.       frameRate: representation.frameRate || null,
  387.       height: representation.height || null,
  388.       mimeType: representation.mimeType,
  389.       channelsCount: representation.numChannels,
  390.       pixelAspectRatio: representation.pixelAspectRatio || null,
  391.       width: representation.width || null,
  392.       label: context.adaptationSet.label || null,
  393.       roles: context.roles || null,
  394.       language: context.adaptationSet.language || null,
  395.     };
  396.   }
  397. };