fix(DASH): Use presentationTimeOffset in EventStream (#7282)

Fixes #7277
shaka-project · Sep 13, 2024 · 8bc639b · 8bc639b
1 parent 1b03baa
commit 8bc639b
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Showing 2 changed files with 37 additions and 1 deletion.
diff --git a/lib/dash/dash_parser.js b/lib/dash/dash_parser.js
@@ -2804,14 +2804,19 @@ shaka.dash.DashParser = class {
     const schemeIdUri = elem.attributes['schemeIdUri'] || '';
     const value = elem.attributes['value'] || '';
     const timescale = TXml.parseAttr(elem, 'timescale', parseNumber) || 1;
+    const presentationTimeOffset =
+      TXml.parseAttr(elem, 'presentationTimeOffset', parseNumber) || 0;
 
     for (const eventNode of TXml.findChildren(elem, 'Event')) {
       const presentationTime =
           TXml.parseAttr(eventNode, 'presentationTime', parseNumber) || 0;
       const duration =
           TXml.parseAttr(eventNode, 'duration', parseNumber) || 0;
 
-      let startTime = presentationTime / timescale + periodStart;
+      // Ensure start time won't be lower than period start.
+      let startTime = Math.max(
+          (presentationTime - presentationTimeOffset) / timescale + periodStart,
+          periodStart);
       let endTime = startTime + (duration / timescale);
       if (periodDuration != null) {
         // An event should not go past the Period, even if the manifest says so.

diff --git a/test/dash/dash_parser_live_unit.js b/test/dash/dash_parser_live_unit.js
@@ -1469,6 +1469,37 @@ describe('DashParser Live', () => {
       expect(onTimelineRegionAddedSpy).toHaveBeenCalledWith(
           jasmine.objectContaining({id: '4'}));
     });
+
+    it('will offset events by given presentationTimeOffset', async () => {
+      const newManifest = [
+        '<MPD>',
+        '  <Period id="1" duration="PT30S">',
+        '    <EventStream schemeIdUri="http://example.com" timescale="1"',
+        '                 presentationTimeOffset="10">',
+        '      <Event presentationTime="10" duration="15"/>',
+        '      <Event presentationTime="25" duration="10"/>',
+        '    </EventStream>',
+        '    <AdaptationSet mimeType="video/mp4">',
+        '      <Representation bandwidth="1">',
+        '        <SegmentTemplate startNumber="1" media="s$Number$.mp4"',
+        '                         duration="2" />',
+        '      </Representation>',
+        '    </AdaptationSet>',
+        '  </Period>',
+        '</MPD>',
+      ].join('\n');
+
+      fakeNetEngine.setResponseText('dummy://foo', newManifest);
+      await parser.start('dummy://foo', playerInterface);
+
+      expect(onTimelineRegionAddedSpy).toHaveBeenCalledTimes(2);
+      expect(onTimelineRegionAddedSpy)
+          .toHaveBeenCalledWith(
+              jasmine.objectContaining({startTime: 0, endTime: 15}));
+      expect(onTimelineRegionAddedSpy)
+          .toHaveBeenCalledWith(
+              jasmine.objectContaining({startTime: 15, endTime: 25}));
+    });
   });
 
   it('honors clockSyncUri for in-progress recordings', async () => {