fix(HLS): Calculate the delay based on the sum of the segment lengths (…

…#7209) Fixes #7206
shaka-project · Aug 26, 2024 · abdabb0 · abdabb0
1 parent b119c03
commit abdabb0
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Showing 2 changed files with 22 additions and 12 deletions.
diff --git a/lib/hls/hls_parser.js b/lib/hls/hls_parser.js
@@ -3410,20 +3410,30 @@ shaka.hls.HlsParser = class {
     // We accomplish this in our DASH-y model by setting a presentation
     // delay of configured value, or 3 segments duration if not configured.
     // This will be the "live edge" of the presentation.
-    let presentationDelay;
+    let presentationDelay = 0;
     if (this.config_.defaultPresentationDelay) {
       presentationDelay = this.config_.defaultPresentationDelay;
     } else if (this.lowLatencyPresentationDelay_) {
       presentationDelay = this.lowLatencyPresentationDelay_;
     } else if (this.presentationDelay_) {
       presentationDelay = this.presentationDelay_;
     } else {
-      const playlistSegments = playlist.segments.length;
+      const totalSegments = playlist.segments.length;
       let delaySegments = this.config_.hls.liveSegmentsDelay;
-      if (delaySegments > (playlistSegments - 2)) {
-        delaySegments = Math.max(1, playlistSegments - 2);
+      if (delaySegments > (totalSegments - 2)) {
+        delaySegments = Math.max(1, totalSegments - 2);
+      }
+      for (let i = totalSegments - delaySegments; i < totalSegments; i++) {
+        const extinfTag = shaka.hls.Utils.getFirstTagWithName(
+            playlist.segments[i].tags, 'EXTINF');
+        if (extinfTag) {
+          const extinfValues = extinfTag.value.split(',');
+          const duration = Number(extinfValues[0]);
+          presentationDelay += Math.ceil(duration);
+        } else {
+          presentationDelay += this.maxTargetDuration_;
+        }
       }
-      presentationDelay = this.maxTargetDuration_ * delaySegments;
     }
 
     if (this.startTime_ && this.startTime_ < 0) {

diff --git a/test/hls/hls_live_unit.js b/test/hls/hls_live_unit.js
@@ -551,7 +551,7 @@ describe('HlsParser live', () => {
         async () => {
           const media = [
             '#EXTM3U\n',
-            '#EXT-X-TARGETDURATION:5\n',
+            '#EXT-X-TARGETDURATION:2\n',
             '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
             '#EXT-X-MEDIA-SEQUENCE:0\n',
             '#EXTINF:2,\n',
@@ -568,14 +568,14 @@ describe('HlsParser live', () => {
             'main.mp4\n',
           ].join('');
           const manifest = await testInitialManifest(master, media);
-          expect(manifest.presentationTimeline.getDelay()).toBe(15);
+          expect(manifest.presentationTimeline.getDelay()).toBe(6);
         });
 
     it('sets 3 times target duration as presentation delay if not configured and clamped to the start', async () => { // eslint-disable-line max-len
       const media = [
         '#EXTM3U\n',
-        '#EXT-X-TARGETDURATION:5\n',
-        '#EXT-X-START:TIME-OFFSET=-10\n',
+        '#EXT-X-TARGETDURATION:2\n',
+        '#EXT-X-START:TIME-OFFSET=-4\n',
         '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
         '#EXT-X-MEDIA-SEQUENCE:0\n',
         '#EXTINF:2,\n',
@@ -592,14 +592,14 @@ describe('HlsParser live', () => {
         'main.mp4\n',
       ].join('');
       const manifest = await testInitialManifest(master, media);
-      expect(manifest.presentationTimeline.getDelay()).toBe(10);
+      expect(manifest.presentationTimeline.getDelay()).toBe(4);
       expect(manifest.startTime).toBe(0);
     });
 
     it('sets 1 times target duration as presentation delay if there are not enough segments', async () => { // eslint-disable-line max-len
       const media = [
         '#EXTM3U\n',
-        '#EXT-X-TARGETDURATION:5\n',
+        '#EXT-X-TARGETDURATION:2\n',
         '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
         '#EXT-X-MEDIA-SEQUENCE:0\n',
         '#EXTINF:2,\n',
@@ -608,7 +608,7 @@ describe('HlsParser live', () => {
         'main.mp4\n',
       ].join('');
       const manifest = await testInitialManifest(master, media);
-      expect(manifest.presentationTimeline.getDelay()).toBe(5);
+      expect(manifest.presentationTimeline.getDelay()).toBe(2);
     });
 
     it('sets presentation delay if defined', async () => {