feat(DASH): Add support for urn:mpeg:dash:ssr:2023 with SegmentTemplate $Number$ (#6745)

Author: avelad

lib/dash/segment_template.js

@@ -96,7 +96,8 @@ shaka.dash.SegmentTemplate = class {
         generateSegmentIndex: () => {
           return SegmentTemplate.generateSegmentIndexFromDuration_(
               shallowCopyOfContext, info, segmentLimit, initSegmentReference,
-              periodDurationMap, aesKey, lastSegmentNumber);
+              periodDurationMap, aesKey, lastSegmentNumber,
+              context.representation.segmentSequenceCadence);
         },
       };
     } else {
@@ -253,6 +254,14 @@ shaka.dash.SegmentTemplate = class {
     const index = MpdUtils.inheritAttribute(
         context, SegmentTemplate.fromInheritance_, 'index');
 
+    const k = MpdUtils.inheritAttribute(
+        context, SegmentTemplate.fromInheritance_, 'k');
+
+    let numChunks = 0;
+    if (k) {
+      numChunks = parseInt(k, 10);
+    }
+
     return {
       segmentDuration: segmentInfo.segmentDuration,
       timescale: segmentInfo.timescale,
@@ -265,6 +274,7 @@ shaka.dash.SegmentTemplate = class {
       indexTemplate: index,
       mimeType: context.representation.mimeType,
       codecs: context.representation.codecs,
+      numChunks: numChunks,
     };
   }
 
@@ -358,12 +368,13 @@ shaka.dash.SegmentTemplate = class {
    * @param {!Object.<string, number>} periodDurationMap
    * @param {shaka.extern.aesKey|undefined} aesKey
    * @param {?number} lastSegmentNumber
+   * @param {number} segmentSequenceCadence
    * @return {!Promise.<shaka.media.SegmentIndex>}
    * @private
    */
   static generateSegmentIndexFromDuration_(
       context, info, segmentLimit, initSegmentReference, periodDurationMap,
-      aesKey, lastSegmentNumber) {
+      aesKey, lastSegmentNumber, segmentSequenceCadence) {
     goog.asserts.assert(info.mediaTemplate,
         'There should be a media template with duration');
 
@@ -483,16 +494,6 @@ shaka.dash.SegmentTemplate = class {
       const segmentMediaTime = segmentPeriodTime +
           info.scaledPresentationTimeOffset;
 
-      const getUris = () => {
-        let time = segmentMediaTime * timescale;
-        if ('BigInt' in window && time > Number.MAX_SAFE_INTEGER) {
-          time = BigInt(segmentMediaTime) * BigInt(timescale);
-        }
-        const mediaUri = MpdUtils.fillUriTemplate(
-            template, id, position, /* subNumber= */ null, bandwidth, time);
-        return ManifestParserUtils.resolveUris(getBaseUris(), [mediaUri]);
-      };
-
       // Relative to the presentation.
       const segmentStart = segmentPeriodTime + periodStart;
       const trueSegmentEnd = segmentStart + segmentDuration;
@@ -505,6 +506,67 @@ shaka.dash.SegmentTemplate = class {
       goog.asserts.assert(segmentStart < segmentEnd,
           'Generated a segment outside of the period!');
 
+      const partialSegmentRefs = [];
+
+      const numChunks = info.numChunks;
+      if (numChunks) {
+        const partialDuration = (segmentEnd - segmentStart) / numChunks;
+
+        for (let i = 0; i < numChunks; i++) {
+          const start = segmentStart + partialDuration * i;
+          const end = start + partialDuration;
+          const subNumber = i + 1;
+          const getPartialUris = () => {
+            let time = segmentMediaTime * timescale;
+            if ('BigInt' in window && time > Number.MAX_SAFE_INTEGER) {
+              time = BigInt(segmentMediaTime) * BigInt(timescale);
+            }
+            const mediaUri = MpdUtils.fillUriTemplate(
+                template, id, position, subNumber, bandwidth, time);
+            return ManifestParserUtils.resolveUris(getBaseUris(), [mediaUri]);
+          };
+          const partial = new shaka.media.SegmentReference(
+              start,
+              end,
+              getPartialUris,
+              /* startByte= */ 0,
+              /* endByte= */ null,
+              initSegmentReference,
+              timestampOffset,
+              /* appendWindowStart= */ periodStart,
+              /* appendWindowEnd= */ getPeriodEnd(),
+              /* partialReferences= */ [],
+              /* tilesLayout= */ '',
+              /* tileDuration= */ null,
+              /* syncTime= */ null,
+              shaka.media.SegmentReference.Status.AVAILABLE,
+              aesKey);
+          partial.codecs = context.representation.codecs;
+          partial.mimeType = context.representation.mimeType;
+          if (segmentSequenceCadence == 0) {
+            if (i > 0) {
+              partial.markAsNonIndependent();
+            }
+          } else if ((i % segmentSequenceCadence) != 0) {
+            partial.markAsNonIndependent();
+          }
+          partialSegmentRefs.push(partial);
+        }
+      }
+
+      const getUris = () => {
+        if (numChunks) {
+          return [];
+        }
+        let time = segmentMediaTime * timescale;
+        if ('BigInt' in window && time > Number.MAX_SAFE_INTEGER) {
+          time = BigInt(segmentMediaTime) * BigInt(timescale);
+        }
+        const mediaUri = MpdUtils.fillUriTemplate(
+            template, id, position, /* subNumber= */ null, bandwidth, time);
+        return ManifestParserUtils.resolveUris(getBaseUris(), [mediaUri]);
+      };
+
       const ref = new shaka.media.SegmentReference(
           segmentStart,
           segmentEnd,
@@ -515,7 +577,7 @@ shaka.dash.SegmentTemplate = class {
           timestampOffset,
           /* appendWindowStart= */ periodStart,
           /* appendWindowEnd= */ getPeriodEnd(),
-          /* partialReferences= */ [],
+          partialSegmentRefs,
           /* tilesLayout= */ '',
           /* tileDuration= */ null,
           /* syncTime= */ null,
@@ -1058,7 +1120,8 @@ shaka.dash.TimelineSegmentIndex = class extends shaka.media.SegmentIndex {
  *   mediaTemplate: ?string,
  *   indexTemplate: ?string,
  *   mimeType: string,
- *   codecs: string
+ *   codecs: string,
+ *   numChunks: number
  * }}
  *
  * @description
@@ -1084,5 +1147,7 @@ shaka.dash.TimelineSegmentIndex = class extends shaka.media.SegmentIndex {
  *   The mimeType.
  * @property {string} codecs
  *   The codecs.
+ * @property {number} numChunks
+ *   The number of chunks in each segment.
  */
 shaka.dash.SegmentTemplate.SegmentTemplateInfo;

test/dash/dash_parser_manifest_unit.js

@@ -2878,6 +2878,43 @@ describe('DashParser Manifest', () => {
       const fourthPartialReference = firstReference.partialReferences[3];
       expect(fourthPartialReference.isIndependent()).toBeFalsy();
     });
+
+    it('with SegmentTemplate and $Number$', async () => {
+      const manifestText = [
+        '<MPD minBufferTime="PT75S">',
+        '  <Period id="1" duration="PT30S">',
+        '    <AdaptationSet id="1" mimeType="video/mp4">',
+        '      <Representation bandwidth="1" codecs="avc1.4d401f">',
+        '        <SegmentTemplate startNumber="1" k="4"',
+        '          media="l-$Number$-p$SubNumber$.mp4"',
+        '          initialization="init.mp4" timescale="50" duration="100">',
+        '        </SegmentTemplate>',
+        '        <SegmentSequenceProperties>',
+        '          <SAP type="1" cadence="1" />',
+        '        </SegmentSequenceProperties>',
+        '      </Representation>',
+        '    </AdaptationSet>',
+        '  </Period>',
+        '</MPD>',
+      ].join('\n');
+
+      fakeNetEngine.setResponseText('dummy://foo', manifestText);
+      /** @type {shaka.extern.Manifest} */
+      const manifest = await parser.start('dummy://foo', playerInterface);
+      const stream = manifest.variants[0].video;
+      await stream.createSegmentIndex();
+      goog.asserts.assert(stream.segmentIndex != null, 'Null segmentIndex!');
+
+      const firstReference = stream.segmentIndex.get(0);
+      const firstPartialReference = firstReference.partialReferences[0];
+      expect(firstPartialReference.isIndependent()).toBeTruthy();
+      const secondPartialReference = firstReference.partialReferences[1];
+      expect(secondPartialReference.isIndependent()).toBeTruthy();
+      const thirdPartialReference = firstReference.partialReferences[2];
+      expect(thirdPartialReference.isIndependent()).toBeTruthy();
+      const fourthPartialReference = firstReference.partialReferences[3];
+      expect(fourthPartialReference.isIndependent()).toBeTruthy();
+    });
   });
 
   describe('supports ContentSteering', () => {

test/dash/dash_parser_segment_template_unit.js

@@ -926,5 +926,6 @@ function makeTemplateInfo(timeline) {
     'indexTemplate': null,
     'mimeType': 'video/mp4',
     'codecs': 'avc1.42E01E',
+    'numChunks': 0,
   };
 }