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Stuttering on 4K Content with audio encoding

stuttering 4k encoding transcoding

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#1 nanuk OFFLINE  

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Posted 07 July 2018 - 01:53 AM

Hi emby Team,
 
I testet as lot and want to describe a problem in detail that really keeps me away from using the emby app of my LG65OLED C7D.
 
I already know that the emby app encodes all audio tracks that are not the first/default audiotrack of a mkv. 
But... emby also encodes the first/default audiotrack if this is Dolby TrueHD/Atmos. Why?
 
and that leads to the/my problem: 
everytime the emby app starts a ffmpeg process to transcode a audio track (for the none default audio track or and thats a much bigger problem... for Dolby TrueHD Tracks) the video begins to stutter... plays for a few seconds than stocks for a few seconds and so on - til the end of the movie :-( )
because many of the 4K remuxes have a Dolby TrueHD/Atmos default track, they are unwatchable via the emby app.
 
1. the problem is reproducable everytime
2. the problem only exists with 4K material (UHD Remuxes)
3. it's not a problem of hardware limitation of the emby server (CPU is 70% idle, gigabit LAN, HDD...)
4. it doesn't matter what kind of audio is being encoded (Atmos, DTS, DD5.1, DTSMA, DTSHD...) 
5. emby dlna plays fine those files because it's playing the files without encoding the audio
 
summarized: audio encoding on 4k remuxes in any way leads to video stuttering!
 
possible solutions:
- stop encoding audio tracks other than the default (like DLNA does)
or
- make TrueHD tracks playable without transcoding (direct play/passthrough)
or
- fix the problem that causes the video stuttering when transcoding audio in 4K movies
 
any questions? don't hesitate to contact me ;-)


#2 Luke OFFLINE  

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Posted 07 July 2018 - 01:55 AM

Hi there, can we please look at an example? Please attach the information requested in how to report a media playback issue. thanks !



#3 nanuk OFFLINE  

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Posted 07 July 2018 - 02:29 AM

Ok...

i started emby server (for a clean log)

played a 4k Remux file with truehd first/default audio track

after a few senconds it begins to stutter as described above... 

 

logs attached ;-)

 

 

Attached Files



#4 Luke OFFLINE  

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Posted 08 July 2018 - 12:47 PM

Can you try lowering the quality setting in the video player, so that it forces a full transcode? Thanks.



#5 nanuk OFFLINE  

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Posted 11 July 2018 - 10:48 AM

Can you try lowering the quality setting in the video player, so that it forces a full transcode? Thanks.

 

Of course I can, but what should it be good for?



#6 Luke OFFLINE  

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Posted 11 July 2018 - 10:58 AM

It would be a useful test. Thanks.

#7 nanuk OFFLINE  

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Posted 12 July 2018 - 01:28 PM

Hi Luke,

here's what you asked for...

 

I startet the 4K HDR Movie again and as soon as it began to stutter (after about a min) I changed the resolution to 1080p what forces a full transcode.

The colours faded out due to the missing HDR to SDR conversion and the cpu went to a very high load.

The stuttering continued but this time I'm not sure if the stuttering is caused by the high cpu load of the transcoding process.

Logs are attached

Attached Files


Edited by nanuk, 12 July 2018 - 01:30 PM.


#8 Luke OFFLINE  

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Posted 13 July 2018 - 01:56 AM

Right with the full transcode it doesn't look like your system can convert it fast enough. Converting 4k hevc can cause very high cpu load. So it looks like the stuttering is potentially two different reasons.

 

Direct play won't happen due to the TrueHD track which LG does not support.



#9 nanuk OFFLINE  

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Posted 13 July 2018 - 03:20 PM

Maybe your Development can analyse what leads to the stuttering of the playback not caused by hardware limitations... (when only the audio is being encoded to ac3 and NO full transcode of 4K material happens)

 

and...

 

"Direct play won't happen due to the TrueHD track which LG does not support." -->

https://www.samma3a....pport-on-lg-tv/

https://www.4kfilme....e-dolby-truehd/  (I don't know of this update has already been rolled out)


Edited by nanuk, 14 July 2018 - 01:42 AM.


#10 Luke OFFLINE  

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Posted 18 July 2018 - 12:39 AM

Unfortunately I don't see anything obvious. Have you tried again with the new 3.5 server release? Thanks.



#11 nanuk OFFLINE  

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Posted 18 July 2018 - 11:12 AM

Unfortunately I don't see anything obvious. Have you tried again with the new 3.5 server release? Thanks.

 

Yes I've tried it an hour ago with Version 3.5 but sadly exactly the same Prob :-/

 

As soon as there is audio encoded the video is stuttering :-(

Am I the only one with the "feature"?!? 

 

Or are so few people using 4K Content?



#12 Luke OFFLINE  

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Posted 18 July 2018 - 01:58 PM

How was it playing?



#13 nanuk OFFLINE  

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Posted 19 July 2018 - 06:02 AM

How was it playing?

 

What exactly do you mean?

 

It played as described in the first post

 

" the video begins to stutter... plays for a few seconds than stocks for a few seconds and so on - til the end of the movie :-( )"

 

this happens everytime when ffmpeg is encoding an audio track :-/

 

I think the best solution is to stop encoding audio tracks other than the default (like DLNA does) - this would make 4K movies watchable ;-)

 

(The problem that I have is not a LG OLED 65C7D prob... it also accurs on my LG 55'' LED in another room)


Edited by nanuk, 19 July 2018 - 06:09 AM.


#14 Luke OFFLINE  

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Posted 19 July 2018 - 11:03 AM

Sorry i meant was it direct playing / remuxing / transcoding, etc. Thanks.



#15 Luke OFFLINE  

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Posted 19 July 2018 - 03:07 PM

We've submitted an update to LG that will support audio track switching without transcoding. Thanks guys.



#16 nanuk OFFLINE  

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Posted 21 July 2018 - 08:21 AM

Sorry i meant was it direct playing / remuxing / transcoding, etc. Thanks.

 

Direct Stream... see Screen attached ;-)

 

Another question....

 

why is Emby encoding everytime subs (even forced subs) are selected?

so again 4K movies with whatever subs selected are not able to be played... no HDR on encoded movies :-(

 

Is this problem also being fixes by the new version of the LG App?

 

"We've submitted an update to LG that will support audio track switching without transcoding."

Attached Files



#17 Luke OFFLINE  

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Posted 21 July 2018 - 08:51 AM

As far as subtitles go, we'd have to look at the ffmpeg log of an example. thanks.



#18 nanuk OFFLINE  

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Posted 21 July 2018 - 09:05 AM

here are the logs ;-)

 

this has not been a problem with last server version... the subs played well, now it's not possible anymore :-/

 

is there any server setting that could be responsible for this? 

I had to reinstall emby a few days ago.

 

 

Attached Files



#19 Luke OFFLINE  

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Posted 21 July 2018 - 09:10 AM

These are PGS subtitles. LG does not support these directly. These are not going to direct play no matter what server version you use. If you want to direct play subtitles, consider acquiring external text based subtitles such as .srt. Our subtitle download feature can help with that.



#20 nanuk OFFLINE  

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Posted 21 July 2018 - 09:17 AM

These are PGS subtitles. LG does not support these directly. These are not going to direct play no matter what server version you use. If you want to direct play subtitles, consider acquiring external text based subtitles such as .srt. Our subtitle download feature can help with that.

 

I swear I've watched exactly this movie with Emby App on my LG in 4K with Subs!! 

This movie has a lot of forced subs ;-)

 

Maybe it was encoded but it was played in 4K HDR and now it's not working anymore :-/

 

Is it neccessary to encode the whole video when having subs?


Edited by nanuk, 21 July 2018 - 10:23 AM.






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