feat(DASH): Add initial support for "urn:mpeg:dash:ssr:2023"

externs/shaka/abr_manager.js

@@ -60,10 +60,12 @@ shaka.extern.AbrManager = class {
 
   /**
    * Chooses one variant to switch to.  Called by the Player.
+   * @param {boolean=} preferFastSwitching If not provided meant "avoid fast
+   *                                       switching if possible".
    * @return {shaka.extern.Variant}
    * @exportDoc
    */
-  chooseVariant() {}
+  chooseVariant(preferFastSwitching) {}
 
   /**
    * Enables automatic Variant choices from the last ones passed to setVariants.
@@ -88,9 +90,11 @@ shaka.extern.AbrManager = class {
    * @param {number} deltaTimeMs The duration, in milliseconds, that the request
    *     took to complete.
    * @param {number} numBytes The total number of bytes transferred.
+   * @param {boolean} allowSwitch Indicate if the segment is allowed to switch
+   *     to another stream.
    * @exportDoc
    */
-  segmentDownloaded(deltaTimeMs, numBytes) {}
+  segmentDownloaded(deltaTimeMs, numBytes, allowSwitch) {}
 
   /**
    * Gets an estimate of the current bandwidth in bit/sec.  This is used by the

externs/shaka/manifest.js

@@ -391,7 +391,8 @@ shaka.extern.FetchCryptoKeysFunction;
  *      (!Array.<shaka.extern.Stream>|!Array.<shaka.extern.StreamDB>|
  *      undefined),
  *   mssPrivateData: (shaka.extern.MssPrivateData|undefined),
- *   external: boolean
+ *   external: boolean,
+ *   fastSwitching: boolean
  * }}
  *
  * @description
@@ -524,6 +525,8 @@ shaka.extern.FetchCryptoKeysFunction;
  * @property {boolean} external
  *   Indicate if the stream was added externally.
  *   Eg: external text tracks.
+ * @property {boolean} fastSwitching
+ *   Indicate if the stream should be used for fast switching.
  *
  * @exportDoc
  */

externs/shaka/offline.js

@@ -140,7 +140,8 @@ shaka.extern.ManifestDB;
  *   spatialAudio: boolean,
  *   closedCaptions: Map.<string, string>,
  *   tilesLayout: (string|undefined),
- *   external: boolean
+ *   external: boolean,
+ *   fastSwitching: boolean
  * }}
  *
  * @property {number} id
@@ -212,6 +213,8 @@ shaka.extern.ManifestDB;
  * @property {boolean} external
  *   Indicate if the stream was added externally.
  *   Eg: external text tracks.
+ * @property {boolean} fastSwitching
+ *   Indicate if the stream should be used for fast switching.
  */
 shaka.extern.StreamDB;
 

lib/abr/simple_abr_manager.js

@@ -165,10 +165,12 @@ shaka.abr.SimpleAbrManager = class {
 
 
   /**
+   * @param {boolean=} preferFastSwitching
+   * @return {shaka.extern.Variant}
    * @override
    * @export
    */
-  chooseVariant() {
+  chooseVariant(preferFastSwitching = false) {
     const SimpleAbrManager = shaka.abr.SimpleAbrManager;
 
     let maxHeight = Infinity;
@@ -190,9 +192,24 @@ shaka.abr.SimpleAbrManager = class {
           maxWidth, this.mediaElement_.clientWidth * devicePixelRatio);
     }
 
+    let normalVariants = this.variants_.filter((variant) => {
+      return !shaka.util.StreamUtils.isFastSwitching(variant);
+    });
+    if (!normalVariants.length) {
+      normalVariants = this.variants_;
+    }
+
+    let variants = normalVariants;
+    if (preferFastSwitching &&
+        normalVariants.length != this.variants_.length) {
+      variants = this.variants_.filter((variant) => {
+        return shaka.util.StreamUtils.isFastSwitching(variant);
+      });
+    }
+
     // Get sorted Variants.
     let sortedVariants = SimpleAbrManager.filterAndSortVariants_(
-        this.config_.restrictions, this.variants_,
+        this.config_.restrictions, variants,
         /* maxHeight= */ Infinity, /* maxWidth= */ Infinity);
 
     if (maxHeight != Infinity || maxWidth != Infinity) {
@@ -206,14 +223,14 @@ shaka.abr.SimpleAbrManager = class {
       }
 
       sortedVariants = SimpleAbrManager.filterAndSortVariants_(
-          this.config_.restrictions, this.variants_, maxHeight, maxWidth);
+          this.config_.restrictions, variants, maxHeight, maxWidth);
     }
 
     const defaultBandwidthEstimate = this.getDefaultBandwidth_();
     const currentBandwidth = this.bandwidthEstimator_.getBandwidthEstimate(
         defaultBandwidthEstimate);
 
-    if (this.variants_.length && !sortedVariants.length) {
+    if (variants.length && !sortedVariants.length) {
       // If we couldn't meet the ABR restrictions, we should still play
       // something.
       // These restrictions are not "hard" restrictions in the way that
@@ -222,7 +239,7 @@ shaka.abr.SimpleAbrManager = class {
       shaka.log.warning('No variants met the ABR restrictions. ' +
                         'Choosing a variant by lowest bandwidth.');
       sortedVariants = SimpleAbrManager.filterAndSortVariants_(
-          /* restrictions= */ null, this.variants_,
+          /* restrictions= */ null, variants,
           /* maxHeight= */ Infinity, /* maxWidth= */ Infinity);
       sortedVariants = [sortedVariants[0]];
     }
@@ -285,7 +302,7 @@ shaka.abr.SimpleAbrManager = class {
    * @override
    * @export
    */
-  segmentDownloaded(deltaTimeMs, numBytes) {
+  segmentDownloaded(deltaTimeMs, numBytes, allowSwitch) {
     shaka.log.v2('Segment downloaded:',
         'deltaTimeMs=' + deltaTimeMs,
         'numBytes=' + numBytes,
@@ -294,7 +311,7 @@ shaka.abr.SimpleAbrManager = class {
     goog.asserts.assert(deltaTimeMs >= 0, 'expected a non-negative duration');
     this.bandwidthEstimator_.sample(deltaTimeMs, numBytes);
 
-    if ((this.lastTimeChosenMs_ != null) && this.enabled_) {
+    if (allowSwitch && (this.lastTimeChosenMs_ != null) && this.enabled_) {
       this.suggestStreams_();
     }
   }

lib/dash/dash_parser.js

@@ -992,6 +992,7 @@ shaka.dash.DashParser = class {
         XmlUtils.findChildren(elem, 'EssentialProperty');
     // ID of real AdaptationSet if this is a trick mode set:
     let trickModeFor = null;
+    let isFastSwitching = false;
     let unrecognizedEssentialProperty = false;
     for (const prop of essentialProperties) {
       const schemeId = prop.getAttribute('schemeIdUri');
@@ -1004,6 +1005,8 @@ shaka.dash.DashParser = class {
       } else if (schemeId == colourPrimariesScheme ||
                  schemeId == matrixCoefficientsScheme) {
         continue;
+      } else if (schemeId == 'urn:mpeg:dash:ssr:2023') {
+        isFastSwitching = true;
       } else {
         unrecognizedEssentialProperty = true;
       }
@@ -1161,6 +1164,7 @@ shaka.dash.DashParser = class {
           closedCaptions, representation, accessibilityPurpose);
       if (parsedRepresentation) {
         parsedRepresentation.hdr = parsedRepresentation.hdr || videoRange;
+        parsedRepresentation.fastSwitching = isFastSwitching;
       }
       return parsedRepresentation;
     }).filter((s) => !!s);
@@ -1475,6 +1479,7 @@ shaka.dash.DashParser = class {
         matchedStreams: [],
         accessibilityPurpose,
         external: false,
+        fastSwitching: false,
       };
     }
 
@@ -1585,6 +1590,7 @@ shaka.dash.DashParser = class {
       numChannels: null,
       audioSamplingRate: null,
       availabilityTimeOffset: 0,
+      segmentSequenceCadence: 0,
     });
     getBaseUris = getBaseUris || parent.getBaseUris;
 
@@ -1635,6 +1641,17 @@ shaka.dash.DashParser = class {
     const availabilityTimeOffset = parent.availabilityTimeOffset + baseUriAto +
         segmentBaseAto + segmentTemplateAto;
 
+    let segmentSequenceCadence = null;
+    const segmentSequenceProperties =
+        XmlUtils.findChild(elem, 'SegmentSequenceProperties');
+    if (segmentSequenceProperties) {
+      const sap = XmlUtils.findChild(segmentSequenceProperties, 'SAP');
+      if (sap) {
+        segmentSequenceCadence = XmlUtils.parseAttr(sap, 'cadence',
+            XmlUtils.parseInt);
+      }
+    }
+
     return {
       getBaseUris: () => ManifestParserUtils.resolveUris(getBaseUris(), uris),
       segmentBase: segmentBase || parent.segmentBase,
@@ -1654,6 +1671,8 @@ shaka.dash.DashParser = class {
       numChannels: numChannels,
       audioSamplingRate: audioSamplingRate,
       availabilityTimeOffset: availabilityTimeOffset,
+      segmentSequenceCadence:
+          segmentSequenceCadence || parent.segmentSequenceCadence,
     };
   }
 
@@ -2080,7 +2099,8 @@ shaka.dash.DashParser.RequestSegmentCallback;
  *   language: ?string,
  *   numChannels: ?number,
  *   audioSamplingRate: ?number,
- *   availabilityTimeOffset: number
+ *   availabilityTimeOffset: number,
+ *   segmentSequenceCadence: number
  * }}
  *
  * @description
@@ -2121,6 +2141,9 @@ shaka.dash.DashParser.RequestSegmentCallback;
  *   Specifies the maximum sampling rate of the content, or null if unknown.
  * @property {number} availabilityTimeOffset
  *   Specifies the total availabilityTimeOffset of the segment, or 0 if unknown.
+ * @property {number} segmentSequenceCadence
+ *   Specifies the cadence of independent segments in Segment Sequence
+ *   Representation.
  */
 shaka.dash.DashParser.InheritanceFrame;
 

lib/dash/mpd_utils.js

@@ -29,22 +29,24 @@ shaka.dash.MpdUtils = class {
    * @param {string} uriTemplate
    * @param {?string} representationId
    * @param {?number} number
+   * @param {?number} subNumber
    * @param {?number} bandwidth
    * @param {?(number|bigint)} time
    * @return {string} A URI string.
    * @see ISO/IEC 23009-1:2014 section 5.3.9.4.4
    */
   static fillUriTemplate(
-      uriTemplate, representationId, number, bandwidth, time) {
+      uriTemplate, representationId, number, subNumber, bandwidth, time) {
     /** @type {!Object.<string, ?number|?string>} */
     const valueTable = {
       'RepresentationID': representationId,
       'Number': number,
+      'SubNumber': subNumber,
       'Bandwidth': bandwidth,
       'Time': time,
     };
 
-    const re = /\$(RepresentationID|Number|Bandwidth|Time)?(?:%0([0-9]+)([diouxX]))?\$/g;  // eslint-disable-line max-len
+    const re = /\$(RepresentationID|Number|SubNumber|Bandwidth|Time)?(?:%0([0-9]+)([diouxX]))?\$/g;  // eslint-disable-line max-len
     const uri = uriTemplate.replace(re, (match, name, widthStr, format) => {
       if (match == '$$') {
         return '$';
@@ -154,6 +156,10 @@ shaka.dash.MpdUtils = class {
           XmlUtils.parseAttr(timePoint, 'd', XmlUtils.parseNonNegativeInt);
       const r = XmlUtils.parseAttr(timePoint, 'r', XmlUtils.parseInt);
 
+      const k = XmlUtils.parseAttr(timePoint, 'k', XmlUtils.parseInt);
+
+      const partialSegments = k || 0;
+
       // Adjust the start time to account for the presentation time offset.
       if (t != null) {
         t -= unscaledPresentationTimeOffset;
@@ -236,6 +242,7 @@ shaka.dash.MpdUtils = class {
           start: startTime / timescale,
           end: endTime / timescale,
           unscaledStart: startTime,
+          partialSegments: partialSegments,
         };
         timeline.push(item);