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.XmlUtils');
  20. goog.requireType('shaka.dash.DashParser');
  21. goog.requireType('shaka.media.PresentationTimeline');
  22. goog.requireType('shaka.media.SegmentReference');
  25. /**
  26.  * @summary A set of functions for parsing SegmentBase elements.
  27.  */
  28. shaka.dash.SegmentBase = class {
  29.   /**
  30.    * Creates an init segment reference from a Context object.
  31.    *
  32.    * @param {shaka.dash.DashParser.Context} context
  33.    * @param {function(?shaka.dash.DashParser.InheritanceFrame):Element} callback
  34.    * @param {shaka.extern.aes128Key|undefined} aes128Key
  35.    * @return {shaka.media.InitSegmentReference}
  36.    */
  37.   static createInitSegment(context, callback, aes128Key) {
  38.     const MpdUtils = shaka.dash.MpdUtils;
  39.     const XmlUtils = shaka.util.XmlUtils;
  40.     const ManifestParserUtils = shaka.util.ManifestParserUtils;
  42.     const initialization =
  43.         MpdUtils.inheritChild(context, callback, 'Initialization');
  44.     if (!initialization) {
  45.       return null;
  46.     }
  48.     let resolvedUris = context.representation.getBaseUris();
  49.     const uri = initialization.getAttribute('sourceURL');
  50.     if (uri) {
  51.       resolvedUris = ManifestParserUtils.resolveUris(resolvedUris, [uri]);
  52.     }
  54.     let startByte = 0;
  55.     let endByte = null;
  56.     const range =
  57.         XmlUtils.parseAttr(initialization, 'range', XmlUtils.parseRange);
  58.     if (range) {
  59.       startByte = range.start;
  60.       endByte = range.end;
  61.     }
  63.     const getUris = () => resolvedUris;
  64.     const qualityInfo = shaka.dash.SegmentBase.createQualityInfo(context);
  65.     return new shaka.media.InitSegmentReference(
  66.         getUris,
  67.         startByte,
  68.         endByte,
  69.         qualityInfo,
  70.         /* timescale= */ null,
  71.         /* segmentData= */ null,
  72.         aes128Key);
  73.   }
  75.   /**
  76.    * Creates a new StreamInfo object.
  77.    *
  78.    * @param {shaka.dash.DashParser.Context} context
  79.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  80.    * @param {shaka.extern.aes128Key|undefined} aes128Key
  81.    * @return {shaka.dash.DashParser.StreamInfo}
  82.    */
  83.   static createStreamInfo(context, requestSegment, aes128Key) {
  84.     goog.asserts.assert(context.representation.segmentBase,
  85.         'Should only be called with SegmentBase');
  86.     // Since SegmentBase does not need updates, simply treat any call as
  87.     // the initial parse.
  88.     const MpdUtils = shaka.dash.MpdUtils;
  89.     const SegmentBase = shaka.dash.SegmentBase;
  90.     const XmlUtils = shaka.util.XmlUtils;
  92.     const unscaledPresentationTimeOffset = Number(MpdUtils.inheritAttribute(
  93.         context, SegmentBase.fromInheritance_, 'presentationTimeOffset')) || 0;
  95.     const timescaleStr = MpdUtils.inheritAttribute(
  96.         context, SegmentBase.fromInheritance_, 'timescale');
  97.     let timescale = 1;
  98.     if (timescaleStr) {
  99.       timescale = XmlUtils.parsePositiveInt(timescaleStr) || 1;
  100.     }
  102.     const scaledPresentationTimeOffset =
  103.         (unscaledPresentationTimeOffset / timescale) || 0;
  105.     const initSegmentReference = SegmentBase.createInitSegment(
  106.         context, SegmentBase.fromInheritance_, aes128Key);
  108.     // Throws an immediate error if the format is unsupported.
  109.     SegmentBase.checkSegmentIndexRangeSupport_(context, initSegmentReference);
  111.     // Direct fields of context will be reassigned by the parser before
  112.     // generateSegmentIndex is called.  So we must make a shallow copy first,
  113.     // and use that in the generateSegmentIndex callbacks.
  114.     const shallowCopyOfContext =
  115.         shaka.util.ObjectUtils.shallowCloneObject(context);
  117.     return {
  118.       generateSegmentIndex: () => {
  119.         return SegmentBase.generateSegmentIndex_(
  120.             shallowCopyOfContext, requestSegment, initSegmentReference,
  121.             scaledPresentationTimeOffset);
  122.       },
  123.     };
  124.   }
  126.   /**
  127.    * Creates a SegmentIndex for the given URIs and context.
  128.    *
  129.    * @param {shaka.dash.DashParser.Context} context
  130.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  131.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  132.    * @param {!Array.<string>} uris
  133.    * @param {number} startByte
  134.    * @param {?number} endByte
  135.    * @param {number} scaledPresentationTimeOffset
  136.    * @return {!Promise.<shaka.media.SegmentIndex>}
  137.    */
  138.   static async generateSegmentIndexFromUris(
  139.       context, requestSegment, initSegmentReference, uris, startByte,
  140.       endByte, scaledPresentationTimeOffset) {
  141.     // Unpack context right away, before we start an async process.
  142.     // This immunizes us against changes to the context object later.
  143.     /** @type {shaka.media.PresentationTimeline} */
  144.     const presentationTimeline = context.presentationTimeline;
  145.     const fitLast = !context.dynamic || !context.periodInfo.isLastPeriod;
  146.     const periodStart = context.periodInfo.start;
  147.     const periodDuration = context.periodInfo.duration;
  148.     const containerType = context.representation.mimeType.split('/')[1];
  150.     // Create a local variable to bind to so we can set to null to help the GC.
  151.     let localRequest = requestSegment;
  152.     let segmentIndex = null;
  154.     const responses = [
  155.       localRequest(uris, startByte, endByte, /* isInit= */ false),
  156.       containerType == 'webm' ?
  157.           localRequest(
  158.               initSegmentReference.getUris(),
  159.               initSegmentReference.startByte,
  160.               initSegmentReference.endByte,
  161.               /* isInit= */ true) :
  162.           null,
  163.     ];
  165.     localRequest = null;
  166.     const results = await Promise.all(responses);
  167.     const indexData = results[0];
  168.     const initData = results[1] || null;
  169.     /** @type {Array.<!shaka.media.SegmentReference>} */
  170.     let references = null;
  172.     const timestampOffset = periodStart - scaledPresentationTimeOffset;
  173.     const appendWindowStart = periodStart;
  174.     const appendWindowEnd = periodDuration ?
  175.         periodStart + periodDuration : Infinity;
  177.     if (containerType == 'mp4') {
  178.       references = shaka.media.Mp4SegmentIndexParser.parse(
  179.           indexData, startByte, uris, initSegmentReference, timestampOffset,
  180.           appendWindowStart, appendWindowEnd);
  181.     } else {
  182.       goog.asserts.assert(initData, 'WebM requires init data');
  183.       references = shaka.media.WebmSegmentIndexParser.parse(
  184.           indexData, initData, uris, initSegmentReference, timestampOffset,
  185.           appendWindowStart, appendWindowEnd);
  186.     }
  188.     presentationTimeline.notifySegments(references);
  190.     // Since containers are never updated, we don't need to store the
  191.     // segmentIndex in the map.
  192.     goog.asserts.assert(!segmentIndex,
  193.         'Should not call generateSegmentIndex twice');
  195.     segmentIndex = new shaka.media.SegmentIndex(references);
  196.     if (fitLast) {
  197.       segmentIndex.fit(appendWindowStart, appendWindowEnd, /* isNew= */ true);
  198.     }
  199.     return segmentIndex;
  200.   }
  202.   /**
  203.    * @param {?shaka.dash.DashParser.InheritanceFrame} frame
  204.    * @return {Element}
  205.    * @private
  206.    */
  207.   static fromInheritance_(frame) {
  208.     return frame.segmentBase;
  209.   }
  211.   /**
  212.    * Compute the byte range of the segment index from the container.
  213.    *
  214.    * @param {shaka.dash.DashParser.Context} context
  215.    * @return {?{start: number, end: number}}
  216.    * @private
  217.    */
  218.   static computeIndexRange_(context) {
  219.     const MpdUtils = shaka.dash.MpdUtils;
  220.     const SegmentBase = shaka.dash.SegmentBase;
  221.     const XmlUtils = shaka.util.XmlUtils;
  223.     const representationIndex = MpdUtils.inheritChild(
  224.         context, SegmentBase.fromInheritance_, 'RepresentationIndex');
  225.     const indexRangeElem = MpdUtils.inheritAttribute(
  226.         context, SegmentBase.fromInheritance_, 'indexRange');
  228.     let indexRange = XmlUtils.parseRange(indexRangeElem || '');
  229.     if (representationIndex) {
  230.       indexRange = XmlUtils.parseAttr(
  231.           representationIndex, 'range', XmlUtils.parseRange, indexRange);
  232.     }
  233.     return indexRange;
  234.   }
  236.   /**
  237.    * Compute the URIs of the segment index from the container.
  238.    *
  239.    * @param {shaka.dash.DashParser.Context} context
  240.    * @return {!Array.<string>}
  241.    * @private
  242.    */
  243.   static computeIndexUris_(context) {
  244.     const ManifestParserUtils = shaka.util.ManifestParserUtils;
  245.     const MpdUtils = shaka.dash.MpdUtils;
  246.     const SegmentBase = shaka.dash.SegmentBase;
  248.     const representationIndex = MpdUtils.inheritChild(
  249.         context, SegmentBase.fromInheritance_, 'RepresentationIndex');
  251.     let indexUris = context.representation.getBaseUris();
  252.     if (representationIndex) {
  253.       const representationUri = representationIndex.getAttribute('sourceURL');
  254.       if (representationUri) {
  255.         indexUris = ManifestParserUtils.resolveUris(
  256.             indexUris, [representationUri]);
  257.       }
  258.     }
  260.     return indexUris;
  261.   }
  263.   /**
  264.    * Check if this type of segment index is supported.  This allows for
  265.    * immediate errors during parsing, as opposed to an async error from
  266.    * createSegmentIndex().
  267.    *
  268.    * Also checks for a valid byte range, which is not required for callers from
  269.    * SegmentTemplate.
  270.    *
  271.    * @param {shaka.dash.DashParser.Context} context
  272.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  273.    * @private
  274.    */
  275.   static checkSegmentIndexRangeSupport_(context, initSegmentReference) {
  276.     const SegmentBase = shaka.dash.SegmentBase;
  278.     SegmentBase.checkSegmentIndexSupport(context, initSegmentReference);
  280.     const indexRange = SegmentBase.computeIndexRange_(context);
  281.     if (!indexRange) {
  282.       shaka.log.error(
  283.           'SegmentBase does not contain sufficient segment information:',
  284.           'the SegmentBase does not contain @indexRange',
  285.           'or a RepresentationIndex element.',
  286.           context.representation);
  287.       throw new shaka.util.Error(
  288.           shaka.util.Error.Severity.CRITICAL,
  289.           shaka.util.Error.Category.MANIFEST,
  290.           shaka.util.Error.Code.DASH_NO_SEGMENT_INFO);
  291.     }
  292.   }
  294.   /**
  295.    * Check if this type of segment index is supported.  This allows for
  296.    * immediate errors during parsing, as opposed to an async error from
  297.    * createSegmentIndex().
  298.    *
  299.    * @param {shaka.dash.DashParser.Context} context
  300.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  301.    */
  302.   static checkSegmentIndexSupport(context, initSegmentReference) {
  303.     const ContentType = shaka.util.ManifestParserUtils.ContentType;
  305.     const contentType = context.representation.contentType;
  306.     const containerType = context.representation.mimeType.split('/')[1];
  308.     if (contentType != ContentType.TEXT && containerType != 'mp4' &&
  309.         containerType != 'webm') {
  310.       shaka.log.error(
  311.           'SegmentBase specifies an unsupported container type.',
  312.           context.representation);
  313.       throw new shaka.util.Error(
  314.           shaka.util.Error.Severity.CRITICAL,
  315.           shaka.util.Error.Category.MANIFEST,
  316.           shaka.util.Error.Code.DASH_UNSUPPORTED_CONTAINER);
  317.     }
  319.     if ((containerType == 'webm') && !initSegmentReference) {
  320.       shaka.log.error(
  321.           'SegmentBase does not contain sufficient segment information:',
  322.           'the SegmentBase uses a WebM container,',
  323.           'but does not contain an Initialization element.',
  324.           context.representation);
  325.       throw new shaka.util.Error(
  326.           shaka.util.Error.Severity.CRITICAL,
  327.           shaka.util.Error.Category.MANIFEST,
  328.           shaka.util.Error.Code.DASH_WEBM_MISSING_INIT);
  329.     }
  330.   }
  332.   /**
  333.    * Generate a SegmentIndex from a Context object.
  334.    *
  335.    * @param {shaka.dash.DashParser.Context} context
  336.    * @param {shaka.dash.DashParser.RequestSegmentCallback} requestSegment
  337.    * @param {shaka.media.InitSegmentReference} initSegmentReference
  338.    * @param {number} scaledPresentationTimeOffset
  339.    * @return {!Promise.<shaka.media.SegmentIndex>}
  340.    * @private
  341.    */
  342.   static generateSegmentIndex_(
  343.       context, requestSegment, initSegmentReference,
  344.       scaledPresentationTimeOffset) {
  345.     const SegmentBase = shaka.dash.SegmentBase;
  347.     const indexUris = SegmentBase.computeIndexUris_(context);
  348.     const indexRange = SegmentBase.computeIndexRange_(context);
  349.     goog.asserts.assert(indexRange, 'Index range should not be null!');
  351.     return shaka.dash.SegmentBase.generateSegmentIndexFromUris(
  352.         context, requestSegment, initSegmentReference, indexUris,
  353.         indexRange.start, indexRange.end,
  354.         scaledPresentationTimeOffset);
  355.   }
  357.   /**
  358.    * Create a MediaQualityInfo object from a Context object.
  359.    *
  360.    * @param {!shaka.dash.DashParser.Context} context
  361.    * @return {!shaka.extern.MediaQualityInfo}
  362.    */
  363.   static createQualityInfo(context) {
  364.     const representation = context.representation;
  365.     return {
  366.       bandwidth: context.bandwidth,
  367.       audioSamplingRate: representation.audioSamplingRate,
  368.       codecs: representation.codecs,
  369.       contentType: representation.contentType,
  370.       frameRate: representation.frameRate || null,
  371.       height: representation.height || null,
  372.       mimeType: representation.mimeType,
  373.       channelsCount: representation.numChannels,
  374.       pixelAspectRatio: representation.pixelAspectRatio || null,
  375.       width: representation.width || null,
  376.     };
  377.   }
  378. };