PGS Subtitles Timing Problem

[argon31]

Hi—when remuxing some titles with makemkv, I end up with weird timing/display issues with PGS subs in MKVs when playing back on an Oppo 103 which as of a year and a half ago supports MKVs with PGS subs.

These issues do not occur with all remuxes/discs, so I am trying to figure our what the problem is.

These issues also do not occur when playing back using mpv/VLC. As I understand it, playback of PGS on software players is probably significantly more straightforward and relies only on PTS whereas hardware players may have more complex implementations based on other timing info that is present in m2ts streams, but not necessarily in MKVs. However, since this doesn't occur on every single remux I play on my Oppo, I wonder if there is a workaround and some way to fix affected titles.

I recently came across a disc that seemed particularly bad. When playing back the remux, subtitle 1 appears, then subtitle 2 replaces it, but then in the gap between subtitle 2 and subtitle 3, subtitle 1 briefly reappears. I suspect that whatever problem is going on has to do with the clearing of subtitles and some sort of conflict between the "clear" subtitles and the duration that is set by makemkv (but as I understand it, doesn't exist in pure-m2ts decoders).

[Woodstock]

Are you seeing the first subtitle appear VERY early, maybe as much as a minute before it is needed? This is a playback issue I've seen with several hardware-based players.

[argon31]

No, the very first subtitle seems at least close to correctly timed.