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Subtitles cause heavy lag

Go to solution Solved by Luke,

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I hope this is the right place to put this topic in, I haven't posted before and it felt like the most relevant place. 

I use Emby regularly, and I primarily watch subbed anime. And as with any tv/movie style there will sometimes be multiple things conveyed on screen. 

So the problem is that whenever there is a large amount of subtitles on screen (Large being above the average single line) the web app will freeze up. So when a sign with multiple slanted lines of text shows up the app freezes on that frame without showing the subtitles and the audio continues without me being able to pause it.  

Another example from today: The episode ends and the ending theme plays, with one line horizontally in English and one vertically in Japanese. The video plays but the subs freeze and the controls don't show up when I move the mouse or click. 


On a related note; is split OP/ED+EP, which is common for blu-ray anime releases, in planning at all?

Please excuse if my English is wrong anywhere.  

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What format are these subtitles.  The embedded blu-ray subs almost certainly require transcoding to render in a web player which means significant CPU resources used on the server.  If that's the case look at your transcode log as your server likely isn't fast enough to do the work.

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They're embedded in the .mkv container and according to emby the codec is SSA (I hope that's what you meant).  

I looked at the logs and I see multiple "parse errors", one at 23:38.94 and the video freezes on 23:39 during the outro. I checked the task manager on the desktop I'm using for emby and my cpu usage rested on 30-40% with emby using 0.8-1.2 during the frozen video. 

Is the task manager lying to me?

*EDIT: Oh and I didn't even see ffmpeg when I was sorting by highest percentage, remembered that it's not actually the emby process that does the encoding.

Edited by lhue
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Also was there an additional ffmpeg log for a subtitle extraction? This would have happened at the time you attempted to play. Thanks.

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  • Solution

What's happening is the subtitle extractions are taking anywhere from 5 to 15 seconds in your cases and yes this can delay playback. However the extraction result is saved for re-use the next time you play the same video.


I am working on adjusting the extraction process to make it faster for the next release of the server.

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