Can you explain this? Win10 VM-Demonic Voice--Audio Out of Sync--750ti


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Hey All, 

 

Hoping someone can offer a bit of an explanation of how this all works.  Been using unraid for NAS/Docker/Media server for quite some time.  I recently brought home a MB/CPU that supported VT-D as I wanted to try out the GPU pass through to hopefully replace the other tower that is connected to my TV.  I set everything up with a win10 vm passing through a 750ti.  First hurdle was the screen was just black.  Figured out I needed to have a secondary video card so I enabled the onboard graphics to bypass that.  Now I have video.

 

Finished the install, download all the drivers, thought I would be good to go.  Then I heard the demonic voice stuff that is covered here, http://lime-technology.com/wiki/index.php/UnRAID_Manual_6#Enable_MSI_for_Interrupts_to_Fix_HDMI_Audio_Support.  Did the reg edit on both the 750ti and the NVIDIA HD audio device.  Demonic sound non-sense taken care of.  

 

Now I figured I was good to go but I can only play a video hulu, netflix, youtube, etc. for a couple mins and the audio and video become out of sync. Now I am coming up to another thread about pinning cpu cores or something.  I don't feel like it should be this hard, something must not be supported.  

 

So for now, I am going to go back to my old setup of an uraid box, and a box that runs my tv...sure glad I found a MB/CPU to test the passthrough with before dropping all the cash for the setup I wanted.  But what the heck is not supported.  Is it determined by the GPU, MB, CPU, or just Settings??  I am more or less out of parts to borrow/throw in to test different combinations but really just want to know what is not working.  

 

Is there anyone of you out there that have experience with this at all?  Is there some info that I could post that would help you tell me where I am going wrong?  From the machine type, Bios, Hyper-v etc....not sure what setting I should be changing or really even where to look.  Is there a setup guide or something out there somewhere that shows recommended setup? I am running unraid 6.3.5.  Everything on the VM I left at the default. 

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  • 2 weeks later...

I have this problem and cant get past it. I have read it is to do with using a cache drive but am unsure. I am hoping to try to dedicate an entire ssd to the VM and hope that sorts it but dont currently have one to try. Very frustrating as the VM with GPU passthrough works fine for everything else!

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  • 3 weeks later...

In one of @gridrunner's two part VM videos, there is a section on demonic sound, and a tool you can DL that takes care of it. Since installing, my sound issues and out-of-sync audio problems have stopped.

 

But I confess that my watching videos is largely limited to YouTube. This is not my normal movie watching perform. So there may be cases I haven't seen. But I suggest you give it a try and see if it clears up your issue.

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The tool maybe automates what you have already done in the registry, but look at this post and there is a link to the tool near the bottom. MSI utility v2 (I used an earlier version which is what was included in the gridrunner's video, but this version seems to eliminate some duplicate entries that show up with the older version).

 

Note the tool needs to be run as administrator.

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Ok sound issues can be the demonic sound issue but the sound going out of sync maybe is something different. That is probably down to how you

are pinning your cores. Make sure you are always pinning hyperthreaded pairs. If not you will get context switching causing latency

which will be noticeable on VMS used for gaming and or media consumption. Also, make sure you are not pinning all your CPUs to the

VM. This isn't necessary and can be counter productive. For a good latency free VM you need "clean cores". Remember unRAID and docker containers

are using CPU cores as well. So if you pin all the cores to a VM, then the other processes will definitely be using the cores the vm is.

If you were running only one OS then the OS can handle all of the context switching because it knows all programmes running on it.

But with a VM its a bit different. unRAID is going to think of your windows VM as one 'programme' it doesn't know whats going on inside it.

Because of this, we have to be careful of how we allocate our resources. Its good practice to leave the first core free as unRAID prefers that core itself.

Also, we can pin docker containers to cores so they can be kept away from the cores which our VM is using.

 

I have made some videos on server tuning which explain pinning cpus etc here 

 

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Ok, i am a little further with this. I have pinned my cores for vm and dockers but it didnt solve anything. So i installed Fedora using the same cores, memory etc as my Windows 10 VM and lo and behold, i dont get any audio lag through the browser whether it is Plex or youtube!

 

So it would appear to be something to do with windows 10. There is definately an issue though that is my work around for now until i can try a dedicated drive for VM's

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