Jellyfin: The Free Software Media System

What file

No comment.

what format, what codecs

MKV/MP4, 264/265

Web interface do the same?

Not sure. Slipped my mind to try that honestly.

During transcoding or direct play?

Both. Though transcoding would seem to keep it to a minimum which is why I was lowering resolution to force it to transcode.

What if you play the file with another program?

Playing them in VLC directly from the file itself I'd have issues from time to time, but this was on another level. Like can't see shit at all.

I probably should have waited a bit and some more troubleshooting before I made a post, I was just really frustrated.