fix(DASH): Segments being fetched out of the range of the timeline (#5889)

Fixes: https://github.com/shaka-project/shaka-player/issues/3952

.gitignore

@@ -7,3 +7,4 @@ coverage/
 .DS_Store
 .vscode
 .babel-cache
+.idea/

lib/dash/mpd_utils.js

@@ -128,11 +128,12 @@ shaka.dash.MpdUtils = class {
    * @param {number} unscaledPresentationTimeOffset
    * @param {number} periodDuration The Period's duration in seconds.
    *   Infinity indicates that the Period continues indefinitely.
+   * @param {number} startNumber
    * @return {!Array.<shaka.media.PresentationTimeline.TimeRange>}
    */
   static createTimeline(
       segmentTimeline, timescale, unscaledPresentationTimeOffset,
-      periodDuration) {
+      periodDuration, startNumber) {
     goog.asserts.assert(
         timescale > 0 && timescale < Infinity,
         'timescale must be a positive, finite integer');
@@ -243,6 +244,7 @@ shaka.dash.MpdUtils = class {
           end: endTime / timescale,
           unscaledStart: startTime,
           partialSegments: partialSegments,
+          segmentPosition: timeline.length + startNumber,
         };
         timeline.push(item);
 
@@ -306,7 +308,7 @@ shaka.dash.MpdUtils = class {
     if (timelineNode) {
       timeline = MpdUtils.createTimeline(
           timelineNode, timescale, unscaledPresentationTimeOffset,
-          context.periodInfo.duration || Infinity);
+          context.periodInfo.duration || Infinity, startNumber);
     }
 
     const scaledPresentationTimeOffset =

lib/dash/segment_template.js

@@ -820,7 +820,7 @@ shaka.dash.TimelineSegmentIndex = class extends shaka.media.SegmentIndex {
     if (!ref) {
       const mediaTemplate = this.templateInfo_.mediaTemplate;
       const range = this.templateInfo_.timeline[correctedPosition];
-      const segmentReplacement = position + this.templateInfo_.startNumber;
+      const segmentReplacement = range.segmentPosition;
       const timeReplacement = this.templateInfo_
           .unscaledPresentationTimeOffset + range.unscaledStart;
       const timestampOffset = this.periodStart_ -

lib/media/presentation_timeline.js

@@ -620,7 +620,8 @@ shaka.media.PresentationTimeline = class {
  *   start: number,
  *   unscaledStart: number,
  *   end: number,
- *   partialSegments: number
+ *   partialSegments: number,
+ *   segmentPosition: number
  * }}
  *
  * @description
@@ -634,6 +635,8 @@ shaka.media.PresentationTimeline = class {
  *   The end time (exclusive) of the range.
  * @property {number} partialSegments
  *   The number of partial segments
+ * @property {number} segmentPosition
+ *   The segment position of the timeline entry as it appears in the manifest
  *
  * @export
  */

test/dash/mpd_utils_unit.js

@@ -459,7 +459,8 @@ describe('MpdUtils', () => {
       console.assert(segmentTimeline);
 
       const timeline = MpdUtils.createTimeline(
-          segmentTimeline, timescale, presentationTimeOffset, periodDuration);
+          segmentTimeline, timescale, presentationTimeOffset,
+          periodDuration, 0);
       expect(timeline).toEqual(
           expected.map((c) => jasmine.objectContaining(c)));
     }