MKV, PGS and forced subtitles

[Nico8583]

Hi,
I'm going to make my own remux to MKV and I have a question about subtitles.
I would like to create MKV and keep PGS subtitles format. But what is the best way to deal with forced subtitles ?
- Set forced flag inside the PGS stream ?
- Set forced flag to track inside MKV ?
- Both ?
Thanks !

[von Suppé]

I've been struggling with forced subtitlings since the day I bought a mediaplayer. Or perhaps the day I bought a second one. Maybe there is no best way, as I find mediaplayers not behaving the same way in handling forced subtitles. Whether they are in a separate force-flagged stream or indiviually flagged within a bigger stream. You'll have to find out for your player what works best. Still then, it would be best for that player only.

To be fool-proof, I long ago decided to just create and mux 2 streams for every used language that contains forced subs. One "full", containing the regular and foreign lines, and one "forced only", containing only the foreign/alien. I don't set any forced flag. I usually flag the "full" one as default. When needed, I swap subs with the remote. Still today reading on problems and frustrations about "forced subs" not working properly on mediaplayers, I think I'll never look back again.

Another thing: when forced subs translate burned-in text, you may want to take care that the two positionings don't interfere. It's not uncommon for burned-in text being located (approx) at the bottom of the video too.

[Nico8583]

Thanks for the answer !
I thought to do the same : keep a full and create a forced only from the full. But set the forced flag to the forced subs when I mux it to MKV.
Why don't you set the forced subs as default instead of full ?
Thanks !

[von Suppé]

Why don't you set the forced subs as default instead of full ?
That's what I did in the early days. I now have a girlfriend who prefers full English.
As she is not so handy (terrible, actually :D) with handling remotes and A/V equipment, for her convenience I set full as default.

[Nico8583]

Thanks, so it's a specific need :D
And if you choose "default" for forced subs, it plays automatically the stream ? You don't need to set "forced" in mkvtoolnix ?
Thanks !

[Chetwood]

Depens entirely on the player which is why I add default and forced flags for the separate streams I create with only forced items in them.

[Nico8583]

Thanks, so if there is a full subtitles track with embedded forced subtitles you separate it as 2 streams, one "forced" and one "full", both without embedded forced flags and you use that ? :
- Video track : default (and/or forced ?)
- Audio track 1 : default (and/or forced ?)
- Audio track 2 : no flag
- Audio track n : no flag
- Subtitles track 1 (without embedded forced flags) "forced" : default and forced
- Subtitles track 1 (without embedded forced flags) "full" : no flag

[von Suppé]

You have to try out for your player. Like Chetwood says, all depends on what type. And available settings. For mkv it's all a different ballgame than with (UHD)BD authoring.

With more than one audiotrack I set the preference to "default". Which actually sets the track "eligible" for default playback. But this has always worked on my players. I have no experience what exactly is implied when setting "forced" to audio.

As an example to the forced subtitling circus, I had a player that only hounoured forced subs when they were in a separate, forced-flagged track and in menu, default subtitle language was set to "Off". Ridiculous.
And even when you think you got it all set, chances are some melt-down @sshole decides to rewrite FW because he thinks to know better.
I chose to avoid that crap. There is a reason why there's a subtitle button on my remote. Of course, do try what works best for you.

[Nico8583]

Thanks, I'll try. I use Nvidia Shield Pro 2019 and Kodi and/or Jellyfin.