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SCC closed captions randomly not displaying

Posted: 22 Oct 2022 09:25
by neilgd72
I have an mp4 file with embedded SCC closed captions. Most of these display fine, but the occasional caption doesn't display.

I have included an example below.

If I use ccConvert then I can see the subtitle, and when I burn the subtitles in using Amazon Mediaconvert then it's there, but VLC doesn't display it.

You can see the file with embedded subtitles here:

https://www.dropbox.com/s/4ix4cypxky7xi ... c.mp4?dl=1

And with them burned in here:

https://www.dropbox.com/s/4yp9f5vz378vn ... t.mp4?dl=1

The missing subtitle is at 06:19

I'm wondering if the caption that's been embedded is malformed or something since AWS Media Live won't pick it up either.

Any help would be much appreciated - Thanks!

Neil

Re: SCC closed captions randomly not displaying

Posted: 22 Oct 2022 12:39
by Lotesdelere
There are no subtitles at all of any kind in your burnt file.

Re: SCC closed captions randomly not displaying

Posted: 22 Oct 2022 13:54
by neilgd72
They're burnt into the burnt file, so appear directly on the screen.

Re: SCC closed captions randomly not displaying

Posted: 23 Oct 2022 18:24
by Lotesdelere
OK, I see what you mean. I can reproduce the issue but it's the same with other FFmpeg based players I've tried. FFplay doesn't even detect the subtitles.
You should create a new report ticket on the VLC Trac with your above report, the links to your sample files and the link to this thread:
https://code.videolan.org/videolan/vlc/-/issues

Re: SCC closed captions randomly not displaying

Posted: 25 Oct 2022 15:24
by neilgd72
Thank you Lotesdelere - I will do that!