Bitmap subtitles with UWP .net9

[4OTbIPE]

Hi! I've noticed some issues with built-in ImageCue subtitles in UWP .NET9. They are displayed in fragments, freeze, or may not be displayed at all. Everything is fine with text subtitles.
Is this a known issue? Am I missing some config property setting?

build 2.0.117-uwp9
Some glitch example:

[brabebhin]

Hi.

Could you provide a test file?

Thanks

PS looking at that clear cut it looks like a problem with the media player element on uwp9, but still I'll check the file.

[4OTbIPE]

The file is quite large (3GB). Will this be ok?

[brabebhin]

Try using the ffmpeg command line to take just a few seconds from it

[4OTbIPE]

https://dropmefiles.com/4UMCk
try download from here
I took a few minutes from the file to more clearly reproduce the problem.

After cutting the file, I encountered another problem. The picture of the cut file at the very beginning of playback either freezes for a few seconds or just a black screen. I don't see such a problem in the standard player. Maybe you will also be able to get this error with this file.

[brabebhin]

VLC seems to exhibit the same issue. So does our master branch and the (net native) UWP samples. So this is not a problem of UWP9 support.
It appears there's a misalignment between the video stream and the audio streams, by judging how playback behaves.

This is an interesting sample. I will take a look when I have some time, but it looks like it was poorly muxed in the the first place (probably when the dub audio was added).