Couldn’t find anything on this. I looked. A bit. Just wondering why subtitles take such a toll, even on my in house streaming. Constant buffering issues and such. And might there eventually be a solution via optimization of PMS code? I don’t want to resort to burn in as I prefer when and where I view the words.
When you find that enabling subtitles is stressing the server’s cpu, then it is because the server is burning the subtitles in.
This is entirely dependent on which plex client you are using and which type of subtitles you have activated.
Hint: chances for playback without the need to “burn in” subtitles are much higher, when your subtitles are in a text-based format (e.g. SRT).
Which clients are you using?
What type of subtitles do you usually have?
What type of device is your server running on?
Thanks a bunch for replying!
Q/A:
Which clients are you using?
-PS4, Win10 via Chrome, several iOS devices
What type of subtitles do you usually have?
-Almost exclusively .srt
What type of device is your server running on?
-Initially Surface Pro 4 (i7, 16gb ram), recently an older Dell XPS 720 monster repurposed solely for server duties.
Both of these machines produce the same buffering issue with subs enabled. However, they have both more than adequately handled multiple streaming duties (up to 5 hd at once) in house and out.
In spite of mad scientist level research regarding a proper dedicated server that can handle my needs in a quiet and lower power capacity, I am still scratching my head at all the various possibilities. I would really like to assemble a nice HTPC that would fit in with my other under the tv components. -sigh-
Thanks again for any suggestions!
@jrgulb said:
-Almost exclusively .srt
That’s a good thing. SRT has the best support among clients to be rendered on the client without requiring help from the server.
Keep in mind, though that SRTs for Plex must use the ‘UTF-8’ text encoding. Also when you get your subtitles from someone/-where else, they might contain errors which can prevent proper function in Plex clients.
Download and installing Subtitle Edit will help you repair these.
-PS4, Win10 via Chrome, several iOS devices
All these devices cannot handle image-based subtitles (the PS4 may be different lately). Therefore the performance impact will be there with all of them.
What they can handle is text-based subtitles. Of which SRT is one of the most common variety.
Chrome might require you to set a preference before it handles SRTs natively:
Settings - Web - Player - ‘Burn subtitles’ = ‘Only Image formats’
(otherwise it may still use the transcoder in the server)
What type of device is your server running on?
-Initially Surface Pro 4 (i7, 16gb ram), recently an older Dell XPS 720 monster repurposed solely for server duties.
Both of these machines produce the same buffering issue with subs enabled. However, they have both more than adequately handled multiple streaming duties (up to 5 hd at once) in house and out.
The surface pro is a tablet, not a server. I’d bet that the cooling system in this device collapses after only a few mintes of 100% cpu load - which is exactly what is going on when the transcoder springs into action. It is not built with that use case in mind.
To prevent a fiery death to the cpu, most machines will forcibly “throttle” the cpu if the cooling system cannot cope. Which could explain the buffering issues you experienced, even though on paper the i7 cpu should have enough grunt to handle the task.
The Dell was a powerful machine - once. Though that was already a few years ago. The cpu power of it is only narrowly over the requirement for transcoding a 1080p video stream. If you now bring ‘burning in’ subtitles into the equation, it is no wonder that you may experience buffering.
If the video has a bitrate over 8mbps or is encoded in VC-1 or even H.265, buffering is inevitable on this cpu.
I would really like to assemble a nice HTPC that would fit in with my other under the tv components.
Not the worst idea.
To my knowledge, OpenPHT/Rasplex and Plex Media Player support image-based subtitles natively. With these clients, you will never have subtitle-induced transcoding going on - thus putting the least stress on the server device.
Hey, OttoKerner, thank you so much for the extensive and well thought out reply! I think I’ll just gut the old Dell and install new components. It’s noisy and energy inefficient, but it’ll do for now. Besides, just noticed the Ethernet adapter is only 10/100. Yikes.
Thanks again!
