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nanuk

Stuttering on 4K Content with audio encoding

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nanuk
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 ;-)

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Luke

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

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nanuk

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?

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Luke

It would be a useful test. Thanks.

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nanuk

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

embyserver.txt

ffmpeg-remux-34ab82cb-fa4b-45d9-bd5b-4ae9f53296ef.txt

ffmpeg-remux-f5aad783-b076-4311-8136-7e2df537c73a.txt

ffmpeg-transcode-6cc199c0-aa4f-4daa-91fb-3bf772bc52f7.txt

ffmpeg-transcode-bf3aef70-2bea-4624-a1dd-487d4cc4d158.txt

Edited by nanuk

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Luke

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.

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nanuk

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.com/tech/en/dolby-truehd-support-on-lg-tv/

https://www.4kfilme.de/lg-2017-oled-update-dolby-truehd/  (I don't know of this update has already been rolled out)

Edited by nanuk

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Luke

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

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nanuk

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?

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Luke

How was it playing?

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nanuk

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

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Luke

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

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Luke

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

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nanuk

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."

post-312532-0-56392700-1532175375_thumb.jpg

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Luke

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

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Luke

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.

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nanuk

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

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nanuk

Hi Luke,

I think I finally found out what causes the stuttering when watching a 4K movie with TrueHD Audio transcoded to AC3.

 

The harddisk with the transcoding directory seems to be the bottleneck.

An incredible amount of files (all about 20mb) are written in the emby transcoding folder, all of the contain about 7 sec. of the movie (picture an sound).

So that the HDD is reading and writing with more than 120mb/s. And thats too much :-/

 

Is this a normal behavior? 

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Luke

That's the transcoding format that we use, yes.

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VellaiT

Hi - Checking if there has been any progress from LG on this as I have the same OLED and issue and unfortunately I just cannot get the same quality picture running HDMI directly from media server to TV... so I am using the LG emby app as the colours are superior... If I play directly from my media server to TV the image looks lifeless and colours washed out.

 

Quite sure my hardware is up to the task - Gigabyte H370N with HDMI 2.0, i7-8700T with Intel 630 HD graphics, 16Gb  DDR4 Memory, 8x Server 7200 SATA drives with 4x 800Gb SSD cache on Windows 10 with storage spaces + NVME OS drive running emby and all equipment running on Cat6 gigabit lan from Meraki enterprise switch....no wifi.

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Luke

Hi, are you having any problems with the app?

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VellaiT

With 4K Remux MPEG-H HEVC 2160p 10bit HDR10 / True HD/Atmos 7.1 24bit, it will pause/stutter on playback every few minutes and the only way I have found to smooth it out is turn subs off completely, switch to 5.1 dolby digital audio track then back to the True HD track then it seems to play for 30 minutes or so before happening again.

 

CPU/Mem/DIsk for media server at these points are hardly being touched so its not Disc I/O or CPU maxing out.

 

When I playback in browser with emby over HDMI to TV the colour is washed out. Same with Kodi.... so would be really like to get the LG app sorted.

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