ffmpeg issue with mkv and pgs subtitles

[funzzy 0]

Hi,

 

I am trying to play some 4k content on my Samsung TV but the emby application do not start the playback at all.

I stay blocked on the hamster wheel and the emby application is no more responsive.

If I set the parameters on the samsung app to never use subtitles, the playback work perfectly. I do not have any problems with included srt subtitles on mkv files.

This issue seems more relatedf to ffmpeg than emby server on synology, but maybe the ffmpeg version used is different between systems.

 

See logs attached.

 

Thanks for your help,

Regards.

 

PS: Synology is a DS415play, emby server is the latest one: 3.2.70.0-1

emby_server.txt

ffmpeg_log.txt

Edited January 20, 2018 by funzzy

[Luke 37057]

Hi, first i would try again but disable subtitles. See how that compares.

 

Samsung does not support PGS subtitles, therefore this will require burning them in on the server with transcoding. And on top of all that, this is 4K hevc.

 

What model is this synology? it may not be able to handle that kind of transcoding. You may want to consider downloading text subtitles if you need subtitles. Thanks.

[funzzy 0]

Hi Luke,

 

Thank you for your answer. The synology version is a DS415play, and it is not able to transcode 4k and hevc. I was not aware that pgs need transcoding.

Disabling the subtitles work correctly. So, ok if I want my subtitles on 4k content I need to convert PGS to srt subtitles.

I have also noticed, when the problem occurs, ffmpeg keeps running on the synology and take a lot of memory despite that emby client has exited or is doing almost nothing.

 

Thank you.

[Luke 37057]

Yea you're not really going to be able to convert pgs to srt because pgs subtitles are images and srt is text. But our subtitle download feature can help you obtain new ones.

 

As far as the hang goes, i noticed that although in this case it's an issue in the ffmpeg process. It was staying open rather than exiting with an error code. In this situation it's difficult to detect that an error has occurred. We can try to fine tune that though. Thanks.

[funzzy 0]

Hi,

 

I removed pgs subtitles on my 4k mkv movie and replaced them by srt subtitles.

If I play the movie without subtitles it play correctly. If I add subtitle I have the same problem, the playback do not start, application keep waiting.

On emby dashboard it says 'direct play' but on ffmpeg logs I see that ffmpeg try to transcode the content, I don't know why.

To recover I must pkill -9 ffmpeg, because my synology become very slow (many memory used but cpu stays around 30%).

I tried the same thing with a mkv file 1080p with srt and it do not need any transcode to play it correctly.

So, why 4k with srt try to transcode ?

 

Attached new ffmpeg log.

 

Thanks.

ffmpeg_log.txt

[Luke 37057]

What subtitles did you add?

[funzzy 0]

Hi,

 

I have generated srt file from pgs using subltitle edit (encoding utf8). Tis program contains an ocr that generate srt text file from pgs images.

 

Thank you

[Luke 37057]

Is it actually valid srt?

[funzzy 0]

Hi,

 

The srt files seems valid, mkvtoolnix used to insert srt on the mkv container seems to do wrong things. vlc complain about the srt files when they are inside the mkv but read them correcly as external subtitles.

I will check what is tthe problem in next days.

 

Thank you.

[Luke 37057]

@@funzzy in the ffmpeg log you posted in post #5, it appears you still have PGS subtitles enabled. Either that or you embedded new subtitles into the video but you didn't run a library scan so that Emby Server can pick up the changes.

 

Keep in mind for best performance we recommend keeping the subtitles external.