feat: Expose PresentationTimeline segment availability duration throu…

…gh Player (#6075)

Closes #2711

lib/cast/cast_utils.js

@@ -355,6 +355,7 @@ shaka.cast.CastUtils.LargePlayerGetterMethods = {
 shaka.cast.CastUtils.PlayerGetterMethodsThatRequireLive = {
   'getPlayheadTimeAsDate': 1,
   'getPresentationStartTimeAsDate': 20,
+  'getSegmentAvailabilityDuration': 20,
 };
 
 

lib/media/presentation_timeline.js

@@ -195,6 +195,17 @@ shaka.media.PresentationTimeline = class {
   }
 
 
+  /**
+   * Gets the presentation's segment availability duration.
+   *
+   * @return {number}
+   * @export
+   */
+  getSegmentAvailabilityDuration() {
+    return this.segmentAvailabilityDuration_;
+  }
+
+
   /**
    * Sets the presentation delay in seconds.
    *

lib/player.js

@@ -4499,6 +4499,29 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     }
   }
 
+  /**
+   * Get the presentation segment availability duration. This should only be
+   * called when the player has loaded a live stream. If the player has not
+   * loaded a live stream, this will return <code>null</code>.
+   *
+   * @return {?number}
+   * @export
+   */
+  getSegmentAvailabilityDuration() {
+    if (!this.isLive()) {
+      shaka.log.warning('getSegmentAvailabilityDuration is for live streams!');
+      return null;
+    }
+
+    if (this.manifest_) {
+      const timeline = this.manifest_.presentationTimeline;
+      return timeline.getSegmentAvailabilityDuration();
+    } else {
+      shaka.log.warning('No way to get segment segment availability duration!');
+      return null;
+    }
+  }
+
   /**
    * Get information about what the player has buffered. If the player has not
    * loaded content or is currently loading content, the buffered content will

test/player_unit.js

@@ -3764,6 +3764,32 @@ describe('Player', () => {
     });
   });
 
+  describe('getSegmentAvailabilityDuration()', () => {
+    beforeEach(async () => {
+      const timeline = new shaka.media.PresentationTimeline(300, 0);
+      timeline.setStatic(false);
+      timeline.setSegmentAvailabilityDuration(1000);
+
+      manifest = shaka.test.ManifestGenerator.generate((manifest) => {
+        manifest.presentationTimeline = timeline;
+        manifest.addVariant(0, (variant) => {
+          variant.addVideo(1);
+        });
+      });
+
+      goog.asserts.assert(manifest, 'manifest must be non-null');
+      await player.load(fakeManifestUri, 0, fakeMimeType);
+    });
+
+    it('gets current segment availability duration', () => {
+      playhead.getTime.and.returnValue(20);
+
+      const segmentAvailabiltyDuration =
+          player.getSegmentAvailabilityDuration();
+      expect(segmentAvailabiltyDuration).toBe(1000);
+    });
+  });
+
   it('rejects empty manifests', async () => {
     manifest = shaka.test.ManifestGenerator.generate();