Bug 266195 – [GStreamer][MSE] media/media-source/media-managedmse-multipletracks-bufferedchange.html is a constant failure

• Status: NEW
• Component: Media

[Jean-Yves Avenard [:jya]]

in test introduced in bug 266169

it is always failing:
```
--- /home/ews/worker/WPE-WK2-Tests-EWS/build/layout-test-results/media/media-source/media-managedmse-multipletracks-bufferedchange-expected.txt
+++ /home/ews/worker/WPE-WK2-Tests-EWS/build/layout-test-results/media/media-source/media-managedmse-multipletracks-bufferedchange-actual.txt
@@ -4,19 +4,19 @@
 RUN(sourceBuffer = source.addSourceBuffer('video/webm; codecs="vp9,opus"'))
 RUN(sourceBuffer.appendBuffer(buffer))
 onbufferedchange called.
-e.addedRanges = [0, 9.999)
+e.addedRanges = [0, 3.416666),[5.333, 9.999666)
 e.removedRanges = []
 EVENT(bufferedchange)
 EVENT(update)
-EXPECTED (sourceBuffer.buffered.length == '1') OK
-video.buffered = [0, 9.999)
-sourceBuffer.buffered = [0, 9.999)
+EXPECTED (sourceBuffer.buffered.length == '1'), OBSERVED '2' FAIL
+video.buffered = [0, 3.416666),[5.333, 9.999666)
+sourceBuffer.buffered = [0, 3.416666),[5.333, 9.999666)
 RUN(source.endOfStream())
-video.buffered = [0, 10.0555)
-sourceBuffer.buffered = [0, 10.0555)
+video.buffered = [0, 3.416666),[5.333, 10.0555)
+sourceBuffer.buffered = [0, 3.416666),[5.333, 10.0555)
 EVENT(sourceended)
 onbufferedchange called.
-e.addedRanges = [9.999, 10.0555)
+e.addedRanges = [9.999666, 10.0555)
 e.removedRanges = []
 EVENT(bufferedchange)
 END OF TEST
```

GStreamer doesn't appear to demux the whole content and is showing as having gap. The last vp9 frame finishes exactly at 9.999, not 9.999666

Inspection with ffprobe shows that there are no discontinuity in this file at 3.416666:

`ffprobe -show_entries packet=pts_time,duration_time,stream_index LayoutTests/media/media-source/content/test-fragmented.webm | less`
```
[PACKET]
stream_index=1
pts_time=3.395000
duration_time=0.020000
[/PACKET]
[PACKET]
stream_index=1
pts_time=3.415000
duration_time=0.020000
[/PACKET]
[PACKET]
stream_index=0
pts_time=3.417000
duration_time=0.041000
[/PACKET]
[PACKET]
stream_index=1
pts_time=3.435000
duration_time=0.020000
[/PACKET]
[PACKET]
stream_index=1
pts_time=3.455000
duration_time=0.020000
[/PACKET]
[PACKET]
stream_index=0
pts_time=3.458000
duration_time=0.041000
[/PACKET]
[PACKET]
stream_index=1
pts_time=3.475000
duration_time=0.020000
```

The timestamps are also weirdly rounded they are all in milliseconds.

output from mkvinfo -a:
```
| + Simple block: key, track number 2, 1 frame(s), timestamp 00:00:03.382000000
|  + Frame with size 284
| + Simple block: key, track number 2, 1 frame(s), timestamp 00:00:03.402000000
|  + Frame with size 286
| + Simple block: key, track number 2, 1 frame(s), timestamp 00:00:03.422000000
|  + Frame with size 274
| + Simple block: track number 1, 1 frame(s), timestamp 00:00:03.417000000
|  + Frame with size 608
| + Simple block: key, track number 2, 1 frame(s), timestamp 00:00:03.442000000
|  + Frame with size 255
| + Simple block: key, track number 2, 1 frame(s), timestamp 00:00:03.462000000
|  + Frame with size 260
| + Simple block: track number 1, 1 frame(s), timestamp 00:00:03.458000000
|  + Frame with size 398
| + Simple block: key, track number 2, 1 frame(s), timestamp 00:00:03.482000000
|  + Frame with size 474
| + Simple block: key, track number 2, 1 frame(s), timestamp 00:00:03.502000000
|  + Frame with size 233
| + Simple block: track number 1, 1 frame(s), timestamp 00:00:03.500000000
|  + Frame with size 458
```


This webm file is made of 2 clusters, the 2nd one starting at 00:00:04.982000000