Buffering Problems when Playing high bitrate 4K remote

[Hypopheralcus 0]

Hi there!

I'm using emby Server on Windows (a dedicated machine mainly for Emby and specifically built for it with a Intel i7-14700K with UHD 770 iGPU, 64 Gigs Memory and a 10 GBit local connection to the storage server, where the media files are located)

Everything is fine on the local network.

Also everything is fine when streaming from remote directly via browser.

Unfortunately things start to go bad when using Nvidia Shield Pro (everything ethernet wired, no wifi in between) from remote (connected via SSL to the Home Network with reverse proxy). When streaming high bitrate 4K files, especially those with Dolby Vision/HDR, remote users on their shields get buffering (e.g. every few seconds or minutes, the video stops for a short time).

My uplink to the Internet is 300 MBit and the Downlink on the other side is even higher.

I have already limited remote bandwith to 50 Mbit per user, so a lot of reserve to the actual bandwith.

Still, the remote stream in such constellations tend to buffer and stutter.

It doesn't seem to be every single time which makes it even more confusing.

 

I enclosed the logfiles of today and 3 transcode logs of one of those instances that buffered. What confused me was the line "Info    Previous transcoding attempt failed. Falling back to software transcoding."

I have a UHD 770 that should transcode multiple 4K Remuxes at the same time - what is going wrong here. Might that be the problem?

Thanks for your help, I'm really a bit desperate.

ffmpeg-transcode-85c8c540-436c-40bc-8195-7e9dce8b78f5_1.txt ffmpeg-transcode-459e1370-87ba-40c3-adfb-5d412485f13a_1.txt ffmpeg-transcode-40c55218-da14-4fa8-bf70-cdd38e0bdb6a_1.txt embyserver.txt

Edited September 20, 2024 by Hypopheralcus

[Abobader 3464]

Hello Hypopheralcus,

** This is an auto reply **

Please wait for someone from staff support or our members to reply to you.

It's recommended to provide more info, as it explain in this thread:

Thank you.

Emby Team

[Lessaj 467]

Since these are 4k HDR/DV they should really be direct playing instead of transcoding. If you have 300 Mbps up I don't recommend limiting to 50 Mbps. Remove the limit and see if they have any playback issues when direct playing.

[rbjtech 5284]

Any transcode will lose hdr/dv so if you have the upload and the client has the download speed, then try and direct play but a 4k remux across the wan is asking a lot regardless of bandwidth - the internet is a shared/contended service afterall.  

The shield is the only device that is likely to direct play because it plays all hd audio, so that is possibly why it is trying to direct play but is being hampered by the 50mbit/sec limit.  I would set it to 70 as that will allow most 4k remux to direct play.  If you don't want direct play,  then set it to 30 which will force a transcode and that is plenty for a 4k stream - a netflix 4k stream is max 20.

[Hypopheralcus 0]

Thank you for both of your answers. 

But I think we are talking about different things. 

My problem is, that everything SHOULD be able to work without buffering and stuttering. The transcode computer should be more than sufficient, the up and downlinks are more than good. 

So why do my remote shields have that problems? 

And why does it say software decoding in that log? 

Thanks for your help 

[yocker 1248]

With my untrained eye looking at these logs.

It seems to have some problems with the subtitles in the file being played
Try and disable your subtitles and see what happens.

Also fails tone mapping which could be a GPU driver problem.
Disable tone mapping and see if that fixes the problem.

I know Intel ARC cards have problems with tone mapping and specific drivers that make tone mapping not work forcing ffmpeg (what Emby uses for transcoding) to go into software transcoding.
Maybe the bug in those drivers has snug it self into the iGPU driver as well.

[rbjtech 5284]

1 hour ago, Hypopheralcus said:

Thank you for both of your answers. 

But I think we are talking about different things. 

My problem is, that everything SHOULD be able to work without buffering and stuttering. The transcode computer should be more than sufficient, the up and downlinks are more than good. 

So why do my remote shields have that problems? 

And why does it say software decoding in that log? 

Thanks for your help 

I didn't look at the logs - sorry it was a late reply from me.

The Emby support tooling is suggesting ffmpeg problems and/or tonemapping problems -

1. Ensure you are using the latest beta incl the ffmpeg.

2. Use the latest drivers from Intel for the UHD 770

3. Ensure you have transcoding set to throttle. (and it's a fast ssd/nvme - which I assume it is)

4. If that still fails - then they will likely need a small sample of the file to test.

I don't personally have any issues transcoding/tonemapping 4K remux's remotely - never tried to a Shield, but that should not make any difference - you will at that point - only be sending SDR (tonemapped from HDR/DV) and AC3 Audio (converted from HD Audio) - unless it's direct playing.

 

 

[yocker 1248]

34 minutes ago, rbjtech said:

I didn't look at the logs - sorry it was a late reply from me.

The Emby support tooling is suggesting ffmpeg problems and/or tonemapping problems -

1. Ensure you are using the latest beta incl the ffmpeg.

2. Use the latest drivers from Intel for the UHD 770

3. Ensure you have transcoding set to throttle. (and it's a fast ssd/nvme - which I assume it is)

4. If that still fails - then they will likely need a small sample of the file to test.

I don't personally have any issues transcoding/tonemapping 4K remux's remotely - never tried to a Shield, but that should not make any difference - you will at that point - only be sending SDR (tonemapped from HDR/DV) and AC3 Audio (converted from HD Audio) - unless it's direct playing.

Really makes me think the intel "tone mapping" bug has found it's way to the iGPU drivers as well.

[Hypopheralcus 0]

6 hours ago, rbjtech said:

Ensure you are using the latest beta incl the ffmpeg.

I'm hesitant because it explicitly says, when downloading the beta installer, that you shouldnt switch between beta and stable on the same installation

6 hours ago, rbjtech said:

Use the latest drivers from Intel for the UHD 770

I just updated to the newest one (but the current one was only 2 Months old and that problem occured before already)

6 hours ago, rbjtech said:

Ensure you have transcoding set to throttle. (and it's a fast ssd/nvme - which I assume it is)

You mean I should ENABLE throttle although my machine is more than fine to do "full speed"? (and yes, i have an NVME - to be precise, I have 2 pcie 4.0 NVME mirrored)

6 hours ago, rbjtech said:

The Emby support tooling

That sounds interesting - where can I download that to test myself?

 

kind regards

[Lessaj 467]

I can't tell from the ffmpeg logs what the transcoding speed is because of how it's reporting it, but especially if it's falling back to software (CPU) that is very difficult to keep up with for a 4K HDR remux compared to a GPU so I wouldn't be surprised if that is what is causing the delay, because at least from the transmission time of the TS segments in the server log it's perfectly acceptable. But this content should not require transcoding, the shield is capable of playing back PGS subtitles natively, it's only transcoding because of the limit you set. So are you saying that you had it basically unlimited before and they were direct playing and still encountering buffering?

Quote

TranscodeReasons=ContainerBitrateExceedsLimit

 

[yocker 1248]

3 hours ago, Hypopheralcus said:

I'm hesitant because it explicitly says, when downloading the beta installer, that you shouldnt switch between beta and stable on the same installation

I just updated to the newest one (but the current one was only 2 Months old and that problem occured before already)

You mean I should ENABLE throttle although my machine is more than fine to do "full speed"? (and yes, i have an NVME - to be precise, I have 2 pcie 4.0 NVME mirrored)

That sounds interesting - where can I download that to test myself?

 

kind regards

Try and disable tone mapping in the transcoding options before doing anything else, have a feeling thats the problem.

[Hypopheralcus 0]

I did a lot of trial and error today. 

It seems somehow, that the quicksync encoding is completely flawed (at least on my machine). Tone mapping doesn't seem to work at all and therefore fallback to software encoding seem to occur regularly. 

Now I tried to deactivate tone mapping but still had issues. 

After a reboot, quicksync didn't even show up any more in the transcoding settings. 

 

Now what I did is, I have a Nvidia rtx 4060 ti in the same machine (which was mainly used for encoding streams of our cctv cameras). So I simply changed the roles, i.e. Used the Nvidia card for emby and the igpu for the cameras.

 

Now what I can already tell is that hardware transcoding including tone mapping seem to work very fine with that GPU. 

What I'm yet waiting for is the resonance of my remote devices, if that also resolved the buffering issue. 

I'll keep you updated. 

[Lessaj 467]

Yes it does seem like there's been a lot of issues with Quicksync lately, definitely prefer Nvidia cards for this task.

[yocker 1248]

Might be Windows messing around with the GPUs to "save power" like on a laptop if disabling tone mapping didn't work.

Maybe there's something to find on google to fix it.

Other than that i'm out of ideas, sorry.

[Hypopheralcus 0]

Ok, so although the transcoding errors are resolved with switching to nvidia, the buffering/freezing still occur remotely.

 

I enclose a "fresh" log from an encode that froze about once a minute.

Does anyone have an idea how to resolve that?

 

Thanks and Kind regards

ffmpeg-transcode-a5ca5115-10c7-45c5-b2f9-a78b7b5526a2_1.txt

[yocker 1248]

11:10:42.313 [hevc @ 000001fb9e47d3c0] Multiple Dolby Vision RPUs found in one AU. Skipping previous.
11:10:42.313 [hevc @ 000001fb9e47d3c0] First slice in a frame missing.

Might be a bad file you are trying to play.

Might also be related to this as hes symptoms sounds pretty much like yours.

[Lessaj 467]

What about when you remove the bitrate limit and it is direct playing instead?

[Hypopheralcus 0]

Removing the Limit is an option AFTER I resolved the problem - because of course I want emby to correctly transcode when necessary.

It seems though, that the issue of the buffering might be connected to some known problems with subtitles. So I now for a test deactivated all subtitles and am yet again waiting for the resonance from the remote users.

[guunter 49]

1 hour ago, Hypopheralcus said:

Removing the Limit is an option AFTER I resolved the problem - because of course I want emby to correctly transcode when necessary.

It seems though, that the issue of the buffering might be connected to some known problems with subtitles. So I now for a test deactivated all subtitles and am yet again waiting for the resonance from the remote users.

I find setting the subtitles to burn in is the best option. You need to have diagnostic plugin installed to see the subtitle options in advanced.

[Hypopheralcus 0]

yes I tried that with force burn in. 

But while that worked with pgsubs it didn't work at all with srt subs (the stream didn't even start) 

And one more thing. I suppose when I force burn in, it forces a transcode every single time, right? So I'd always lose hdr and dv, even if direct play would be possible? 

[guunter 49]

Just now, Hypopheralcus said:

yes I tried that with force burn in. 

But while that worked with pgsubs it didn't work at all with srt subs (the stream didn't even start) 

And one more thing. I suppose when I force burn in, it forces a transcode every single time, right? So I'd always lose hdr and dv, even if direct play would be possible? 

No the subtitles burn in are separate and would be using your cpu while video transcodes are done by the gpu. You can see the process while playing a video if you look at user sessions.

[Hypopheralcus 0]

24 minutes ago, guunter said:

No the subtitles burn in are separate and would be using your cpu while video transcodes are done by the gpu. You can see the process while playing a video if you look at user sessions.

 

So that means, even with burn-in (and although emby can't encode in h265), it preserves DV and HDR when direct play is possible?

And do you have any idea, why the SRT didn't work with burn in?

Edited September 22, 2024 by Hypopheralcus

[guunter 49]

23 minutes ago, Hypopheralcus said:

 

So that means, even with burn-in (and although emby can't encode in h265), it preserves DV and HDR when direct play is possible?

And do you have any idea, why the SRT didn't work with burn in?

My SRT works I don’t know why yours isn’t.

you turned off subtitle extraction in transcoding and enabled burn in on the subtitle options? I’m on beta so I don’t know if it looks different. 

[Hypopheralcus 0]

22 minutes ago, guunter said:

you turned off subtitle extraction in transcoding and enabled burn in on the subtitle options?

Yes, i turned off extraction in the transcoding area and activated "Force Subtitle Burn-In" in the diagnostic options

[guunter 49]

11 minutes ago, Hypopheralcus said:

Yes, i turned off extraction in the transcoding area and activated "Force Subtitle Burn-In" in the diagnostic options

That’s the wrong thing. Settings in diagnostic options don’t persist a reboot and that’s not how I got burn in working. You should have a subtitles options like in the screenshot