hello plex developers,
just noticed that when I'm playing a video at it's native solution in safari, plex uses very little cpu power on synology servers. but as soon as i enable subtitles, the cpu usage sky rockets. (transcode a 20gb 1080 bluray just to add a 100kb subtitle, and if i switch a subtitle i need to transcode this 20gb again? this doesnt make any sense)
so i guess the way plex handles subtitles is transcoding in INTO the video, make it like a part of the video. which makes sense since when i switch to lower resolutions, the subtitles get blurred too.
so here's my suggestion,
why don't you handle the subtitles by 'pushing' it to the clients, as texts. and let the client display the subtitles ON TOP of the videos. just like iOS handles those subtitles build in the videos (sorry don't know how to describe). I believe the synology DS Video handles subtitles in this way
and the benefit of doing this:
1. in many situations, plex transcodes videos JUST to add subtitles, so if we do this, plex no longer need to transcode the videos, (only transcode audio if needed). so that plex uses less power and therefore, is more useable/useful on more low-power devices, such like WD cloud drives. and also it needs less buffer time.
2. also, if I'm having a poor connection and i need to switch to lower resolutions, say 480p (which usually uses more cpu power, and can also be benefit like said above). now my subtitles are getting blurred too, which doesnt make any sense. if we push subtitles, no matter how my video quality is, my subtitles are always sharp and clear, easy to read. usually a subtitle file is just 100kb or less for a full length movie, it will not add any stress to any network.
3. easier to switch subtitles. in current situation, when i want to switch a subtitle, not only plex need to transcode the video AGAIN, (which again, adds cpu consumption and wait time), but also on my client, i need to throw buffered video away (which can be MB's instead of KB's for subtitles). but if we push the subtitle, all i need is another 100kb subtitles, no wait time, no re-transcode. all it's wasted is the old subtitle (~100KB)
i don't know why plex is not doing this, maybe compatibility issue of old devices? but i guess most modern OS has the ability to add external subtitles on top of a video?
and doing this will enable plex server to be used on a wider range of devices, since audio transcoding is WAY easier and faster than video+audio transcoding. those low-power devices, like WD My Cloud, will now have a better performance with plex.
