Server Version#: PlexMediaServer-1.21.3.4046-3c1c83ba4-x86_64
Player Version#: 4.51.1 & Samsung TV (old) Plex app.
Synology DS918+
I’ve read many topics on optimize, transcoding, and subtitles. I am here to report my findings for those future searchers trying to resolve my same situation. So many posts are closed even though they remain relevant and unresolved.
I have a few seasons of a TV series in MKV container, HEVC 1080p 3mbps and AAC-6… .with embedded ‘internal PGS’ subtitle tracks. One for the foreign language only and one for all dialog.
I read all about how the hardware transcoding is getting slowed down by injecting the subtitles, and I get buffering which I’ve reduced by tweaking settings… …but not eliminated. It’s also nearly impossible on my TV client to jump forward or back without it timing out (although the web client seems to be patient enough to allow it to eventually catch up). The buffering makes it unwatchable. I read (but haven’t tested) that I could actually just turn off hardware transcoding and it might keep up. No subtitles: Direct Play. Subtitles on: Transcoding.
I’m not here to request features; many others have done that. However, I suffered the following surprise. If I “Optimize” for TV, I get the subtitles burned in (other posts reporting not getting any!) I couldn’t figure out how it was choosing which track, so I assumed it was just using the first. That’s not correct. I kicked off an optimize for all seasons. I had the first 3 episode of season 1 work correctly–but none of the others had subtitles in the optimized version. It took a while to figure out: Plex is retaining my subtitle selection from the last time I played the track in order to optimize and burn them in!
So only those I had already played had subtitles, none of the remaining episodes or seasons did.
My solution was to remove all the optimized copies, and start each episode, switch to subtitle track I wanted, then stop it and jump over the optimize. That takes a very long time in the interface compared to selecting an entire season… …but (so far), it is working as planned.
To make that lesson more painful, Plex is really bad at removing optimized versions-- don’t even try to delete them from the filesystem. Even if you use the plex interface, it often still thinks the optimized versions exist (but doesn’t show multiple versions) and will not recreate them (or claim it did but 0 files). You must go to the list of optimized stuff and delete every single succeeded (or failed) attempt in order to clean out the history. Then it will recreate them.
So lesson learned, you want to burn in embedded subtitles? Select subtitle, then optimize. …for each episode. …unless someone can tell me how to set that for all of them at once.
