fix(HLS): Fix load of LL-HLS when the partial segment is not independent (#5277)

Author: avelad

lib/hls/hls_parser.js

@@ -2895,6 +2895,9 @@ shaka.hls.HlsParser = class {
         if (item.name == 'EXT-X-PRELOAD-HINT') {
           partial.markAsPreload();
         }
+        if (item.getAttributeValue('INDEPENDENT') != 'YES') {
+          partial.markAsNonIndependent();
+        }
         partialSegmentRefs.push(partial);
       } // for-loop of hlsSegment.partialSegments
     }

lib/media/segment_reference.js

@@ -265,6 +265,9 @@ shaka.media.SegmentReference = class {
     /** @type {boolean} */
     this.preload = false;
 
+    /** @type {boolean} */
+    this.independent = true;
+
     /** @type {?shaka.extern.HlsAes128Key} */
     this.hlsAes128Key = hlsAes128Key;
 
@@ -407,6 +410,25 @@ shaka.media.SegmentReference = class {
     return this.preload;
   }
 
+  /**
+   * Mark the reference as non-independent.
+   *
+   * @export
+   */
+  markAsNonIndependent() {
+    this.independent = false;
+  }
+
+  /**
+   * Returns true if the segment is independent.
+   *
+   * @return {boolean}
+   * @export
+   */
+  isIndependent() {
+    return this.independent;
+  }
+
   /**
    * Set the segment's thumbnail sprite.
    *

lib/media/streaming_engine.js

@@ -1262,6 +1262,17 @@ shaka.media.StreamingEngine = class {
             mediaState.stream.segmentIndex.getIteratorForTime(presentationTime);
         ref = mediaState.segmentIterator &&
             mediaState.segmentIterator.next().value;
+        // For LL-HLS we need to find the nearest INDEPENDENT segment
+        let attempt = 0;
+        const maxAttempts = 5;
+        while (ref && !ref.isIndependent() && attempt < maxAttempts) {
+          const newTime = ref.startTime - 0.1;
+          mediaState.segmentIterator =
+              mediaState.stream.segmentIndex.getIteratorForTime(newTime);
+          ref = mediaState.segmentIterator &&
+              mediaState.segmentIterator.next().value;
+          attempt++;
+        }
       }
       if (ref == null) {
         shaka.log.warning(logPrefix, 'cannot find segment',

test/hls/hls_live_unit.js

@@ -634,14 +634,17 @@ describe('HlsParser live', () => {
         '#EXT-X-MEDIA-SEQUENCE:0\n',
         // ref includes partialRef, partialRef2
         // partialRef
-        '#EXT-X-PART:DURATION=2,URI="partial.mp4",BYTERANGE=200@0\n',
+        '#EXT-X-PART:DURATION=2,URI="partial.mp4",BYTERANGE=200@0,',
+        'INDEPENDENT=YES\n',
         // partialRef2
-        '#EXT-X-PART:DURATION=2,URI="partial2.mp4",BYTERANGE=230@200\n',
+        '#EXT-X-PART:DURATION=2,URI="partial2.mp4",BYTERANGE=230@200,',
+        'INDEPENDENT=YES\n',
         '#EXTINF:4,\n',
         'main.mp4\n',
         // ref2 includes partialRef3, preloadRef
         // partialRef3
-        '#EXT-X-PART:DURATION=2,URI="partial.mp4",BYTERANGE=210@0\n',
+        '#EXT-X-PART:DURATION=2,URI="partial.mp4",BYTERANGE=210@0,',
+        'INDEPENDENT=YES\n',
         // preloadRef
         '#EXT-X-PRELOAD-HINT:TYPE=PART,URI="partial.mp4",BYTERANGE-START=210,',
         'BYTERANGE-LENGTH=210\n',
@@ -668,6 +671,7 @@ describe('HlsParser live', () => {
           'test:/partial.mp4', 6, 7.5, /* syncTime= */ null,
           /* baseUri= */ '', /* startByte= */ 210, /* endByte= */ 419);
       preloadRef.markAsPreload();
+      preloadRef.markAsNonIndependent();
 
       // ref2 is not fully published yet, so it doesn't have a segment uri.
       const ref2 = makeReference(
@@ -693,7 +697,8 @@ describe('HlsParser live', () => {
         'main.mp4\n',
         // ref2 includes partialRef, but not preloadRef
         // partialRef
-        '#EXT-X-PART:DURATION=2,URI="partial.mp4",BYTERANGE=210@0\n',
+        '#EXT-X-PART:DURATION=2,URI="partial.mp4",BYTERANGE=210@0,',
+        'INDEPENDENT=YES\n',
         // preloadRef
         '#EXT-X-PRELOAD-HINT:TYPE=PART,URI="partial.mp4",BYTERANGE-START=210\n',
       ].join('');

test/hls/hls_parser_unit.js

@@ -2559,8 +2559,8 @@ describe('HlsParser', () => {
         '#EXTINF:5,\n',
         'main.mp4\n',
         '#EXT-X-PROGRAM-DATE-TIME:2000-01-01T00:00:15.00Z\n',
-        '#EXT-X-PART:DURATION=2.5,URI="main.mp4"\n',
-        '#EXT-X-PART:DURATION=2.5,URI="main.mp4"\n',
+        '#EXT-X-PART:DURATION=2.5,URI="main.mp4",INDEPENDENT=YES\n',
+        '#EXT-X-PART:DURATION=2.5,URI="main.mp4",INDEPENDENT=YES\n',
         '#EXTINF:5,\n',
         'main.mp4\n',
         '#EXT-X-PROGRAM-DATE-TIME:2000-01-01T00:00:20.00Z\n',