feat(hls): parse EXT-X-GAP (#4134)

Parse EXT-X-GAP HLS tag and add a status enum to shaka.media.SegmentReference.

shaka.media.SegmentReference.Status.AVAILABLE --> Normal behaviour
shaka.media.SegmentReference.Status. UNAVAILABLE --> Related to #2541
shaka.media.SegmentReference.Status. MISSING --> EXT-X-GAP in HLS

Note: only the parsing is added, but the functionality is not yet implemented.

Issue #1308

lib/hls/hls_parser.js

@@ -1865,6 +1865,11 @@ shaka.hls.HlsParser = class {
       }
     }
 
+    let status = shaka.media.SegmentReference.Status.AVAILABLE;
+    if (shaka.hls.Utils.getFirstTagWithName(tags, 'EXT-X-GAP')) {
+      status = shaka.media.SegmentReference.Status.MISSING;
+    }
+
     // Create SegmentReferences for the partial segments.
     const partialSegmentRefs = [];
     if (this.lowLatencyMode_ && hlsSegment.partialSegments.length) {
@@ -1978,6 +1983,7 @@ shaka.hls.HlsParser = class {
         tilesLayout,
         tileDuration,
         syncTime,
+        status,
     );
   }
 

lib/media/segment_reference.js

@@ -162,12 +162,15 @@ shaka.media.SegmentReference = class {
    * @param {?number=} syncTime
    *  A time value, expressed in the same scale as the start and end time, which
    *  is used to synchronize between streams.
+   * @param {shaka.media.SegmentReference.Status=} status
+   *  The segment status is used to indicate that a segment does not exist or is
+   *  not available.
    */
   constructor(
       startTime, endTime, uris, startByte, endByte, initSegmentReference,
       timestampOffset, appendWindowStart, appendWindowEnd,
       partialReferences = [], tilesLayout = '', tileDuration = null,
-      syncTime = null) {
+      syncTime = null, status = shaka.media.SegmentReference.Status.AVAILABLE) {
     // A preload hinted Partial Segment has the same startTime and endTime.
     goog.asserts.assert(startTime <= endTime,
         'startTime must be less than or equal to endTime');
@@ -220,6 +223,9 @@ shaka.media.SegmentReference = class {
 
     /** @type {?number} */
     this.syncTime = syncTime;
+
+    /** @type {shaka.media.SegmentReference.Status} */
+    this.status = status;
   }
 
   /**
@@ -315,6 +321,39 @@ shaka.media.SegmentReference = class {
   getTileDuration() {
     return this.tileDuration;
   }
+
+  /**
+   * Returns the segment's status.
+   *
+   * @return {shaka.media.SegmentReference.Status}
+   * @export
+   */
+  getStatus() {
+    return this.status;
+  }
+
+  /**
+   * Mark the reference as unavailable.
+   *
+   * @export
+   */
+  markAsUnavailable() {
+    this.status = shaka.media.SegmentReference.Status.UNAVAILABLE;
+  }
+};
+
+
+/**
+ * Rather than using booleans to communicate what the state of the reference,
+ * we have this enum.
+ *
+ * @enum {number}
+ * @export
+ */
+shaka.media.SegmentReference.Status = {
+  AVAILABLE: 0,
+  UNAVAILABLE: 1,
+  MISSING: 2,
 };
 
 

test/hls/hls_parser_unit.js

@@ -1424,6 +1424,105 @@ describe('HlsParser', () => {
     }
   });
 
+  it('parse EXT-X-GAP', async () => {
+    const master = [
+      '#EXTM3U\n',
+      '#EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="aud1",LANGUAGE="eng",',
+      'CHANNELS="2",URI="audio"\n',
+      '#EXT-X-STREAM-INF:BANDWIDTH=200,CODECS="avc1,mp4a",',
+      'RESOLUTION=960x540,FRAME-RATE=60,AUDIO="aud1"\n',
+      'video\n',
+    ].join('');
+
+    const video = [
+      '#EXTM3U\n',
+      '#EXT-X-PLAYLIST-TYPE:VOD\n',
+      '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
+      '#EXTINF:5,\n',
+      'main.mp4\n',
+      '#EXTINF:5,\n',
+      '#EXT-X-GAP\n',
+      'main.mp4\n',
+      '#EXTINF:5,\n',
+      'main.mp4\n',
+    ].join('');
+
+    const audio = [
+      '#EXTM3U\n',
+      '#EXT-X-PLAYLIST-TYPE:VOD\n',
+      '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
+      '#EXTINF:5,\n',
+      'main.mp4\n',
+      '#EXTINF:5,\n',
+      '#EXT-X-GAP\n',
+      'main.mp4\n',
+      '#EXTINF:5,\n',
+      'main.mp4\n',
+    ].join('');
+
+    fakeNetEngine
+        .setResponseText('test:/master', master)
+        .setResponseText('test:/audio', audio)
+        .setResponseText('test:/video', video)
+        .setResponseValue('test:/init.mp4', initSegmentData)
+        .setResponseValue('test:/main.mp4', segmentData);
+
+    const actual = await parser.start('test:/master', playerInterface);
+
+    expect(actual.variants.length).toBe(1);
+
+    const variant = actual.variants[0];
+    expect(variant.video).toBeTruthy();
+    expect(variant.audio).toBeTruthy();
+
+    const available = shaka.media.SegmentReference.Status.AVAILABLE;
+    const missing = shaka.media.SegmentReference.Status.MISSING;
+
+    await variant.video.createSegmentIndex();
+    goog.asserts.assert(variant.video.segmentIndex != null,
+        'Null segmentIndex!');
+
+    const firstVideoReference = variant.video.segmentIndex.get(0);
+    const secondVideoReference = variant.video.segmentIndex.get(1);
+    const thirdVideoReference = variant.video.segmentIndex.get(2);
+
+    expect(firstVideoReference).not.toBe(null);
+    expect(secondVideoReference).not.toBe(null);
+    expect(thirdVideoReference).not.toBe(null);
+
+    if (firstVideoReference) {
+      expect(firstVideoReference.getStatus()).toBe(available);
+    }
+    if (secondVideoReference) {
+      expect(secondVideoReference.getStatus()).toBe(missing);
+    }
+    if (thirdVideoReference) {
+      expect(thirdVideoReference.getStatus()).toBe(available);
+    }
+
+    await variant.audio.createSegmentIndex();
+    goog.asserts.assert(variant.audio.segmentIndex != null,
+        'Null segmentIndex!');
+
+    const firstAudioReference = variant.audio.segmentIndex.get(0);
+    const secondAudioReference = variant.audio.segmentIndex.get(1);
+    const thirdAudioReference = variant.audio.segmentIndex.get(2);
+
+    expect(firstAudioReference).not.toBe(null);
+    expect(secondAudioReference).not.toBe(null);
+    expect(thirdAudioReference).not.toBe(null);
+
+    if (firstAudioReference) {
+      expect(firstAudioReference.getStatus()).toBe(available);
+    }
+    if (secondAudioReference) {
+      expect(secondAudioReference.getStatus()).toBe(missing);
+    }
+    if (thirdAudioReference) {
+      expect(thirdAudioReference.getStatus()).toBe(available);
+    }
+  });
+
   it('Disable audio does not create audio streams', async () => {
     const master = [
       '#EXTM3U\n',