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daniellippens  
#1 Posted : Wednesday, October 12, 2022 5:01:34 AM(UTC)
daniellippens

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When using Dante Virtual Soundcard in ASIO mode audio seems to be late to video.
I'm used to video being late and delaying audio but now the inverse is happening.
Any idea how to get the latency lower? I don't really want to delay the video as this is extremely resource-intensive.

Cheers,
Daniel
Roy Sinclair  
#2 Posted : Wednesday, October 12, 2022 5:51:08 AM(UTC)
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Originally Posted by: daniellippens Go to Quoted Post
When using Dante Virtual Soundcard in ASIO mode audio seems to be late to video.
I'm used to video being late and delaying audio but now the inverse is happening.
Any idea how to get the latency lower? I don't really want to delay the video as this is extremely resource-intensive.

Cheers,
Daniel


Are you sure it's in ASIO mode and not running through WDM drivers? Also if resources are a restriction, are you running at high CPU usage?

Virtual Soundcard means it's running IN the CPU so if you were close to the edge already this may be a problem.

Lastly you should check your network speed under load, how long does it take to round-trip a ping to the equipment sending the sound?
daniellippens  
#3 Posted : Thursday, October 13, 2022 11:02:10 PM(UTC)
daniellippens

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Yes the DVS is definitely running in ASIO mode. CPU usage is low. I’m not running close to the edge but i just don’t feel like delaying video.

Round trip times are under 1ms. Audio gear is on the same switch.
daniellippens  
#4 Posted : Wednesday, September 13, 2023 9:47:56 AM(UTC)
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I'd like to bump this topic as no matter what i do and no matter on what machine i run vMix with DVS audio is always late by a few frames. It happens in DVS ASIO but also in DVS WDM. I've tried everything on the Dante side to get latency down as low as possible but i feel like vMix is introducing latency to my audio coming in over Dante.

Setting a negative audio delay in vMix doesn't seem to do anything.

I'm really hoping someone has figured this out.
mavik  
#5 Posted : Friday, September 15, 2023 8:43:40 PM(UTC)
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Just some basics worth checking.
- Clocks, sync everything to NTP if possible and check they are all on the same time. Dante relies heavily on clocks
- Check ASIO buffer size and Delay settings in DVS
- enable IGMP snooping on the switch, set the IGMP querrier to a central unit
- disable any green or eco modes on the switch
- Check the VLAN config, check if you have VLAN bridging that could mean a detour for packets.
- When working wit VLANs check that the MTU is reduced to avoid repacketizing at switch port level

Hope that helps to check the basics
Andrew  
#6 Posted : Tuesday, October 3, 2023 5:39:27 AM(UTC)
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Jumping in here as I've recently experienced similar where the audio is considerably later than the video (up to 6 frames), with both RME and Focusrite interfaces.

Short answer, setting Audio Gap Handling to Resample has fixed it.


Long answer:

Sometimes once we've built a project and do a sync check, the audio is somehow later than the video (Blackmagic SDI capture).

Yet in a empty clean project, it is not.

This is more common in the heavier projects where vMix has to work harder, and especially so if running at 59.94.

At first I thought vMix was getting exceptionally fast at processing video!.. But under further investiagion this is unfortunately not the case, vMix is just getting slower at audio.

It's also wildly unpredictable. It can be off by 3 frames in one test, then 6 frames in the next test, without changing a thing or even restarting vMix. (Which makes compensating for it by delaying the cameras sources tricky, as you can't reference the current recording.)

After 2 full days of testing and retesting with all the variables I can think of, I resorted to trying settings which should have absolutely no influence whatsover... Such as the gap handling.

Some interesting discoveries on this journey:
Cheap Behringer device was far less affected by this issue, no idea why.
SDI audio channels are not guaranteed to be in sync with the video! (In vMix)
There is always a sync variability between recordings of up to a frame. Presumably this is because the video and audio are not locked in any way so vMix starts the audio recording with the video frame it happens to have at that moment in time.
The time to screen latency is very consistent between tests and even varying project loads, for every framerate. It is not however the same number of frames at different frame rates!






ritzoli  
#7 Posted : Sunday, December 31, 2023 2:17:58 AM(UTC)
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Hello,
be sure all devices have the same encodage into the DANTE controler : PCM 32 or PCM 16 or PCM 24

In my DANTE controler I found out the issue, my X32 was in PCM 16 and my 2 PCs in PCM 24.

As vMix seems to try to use PCM 32 float on all audio devices, I configured all DANTE devices to PCM 32, I also forced all DVS to run at 32bits 48000hz into the Windows Audio Control Panel (card by card IN + OUT).

It seems to work.

Hope that will help.


Olivier
markleman  
#8 Posted : Tuesday, January 2, 2024 8:03:36 AM(UTC)
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Originally Posted by: ritzoli Go to Quoted Post
Hello,
In my DANTE controller I found out the issue, my X32 was in PCM 16 and my 2 PCs in PCM 24.

As vMix seems to try to use PCM 32 float on all audio devices, I configured all DANTE devices to PCM 32


That is interesting. We currently use an XR18 mixer over USB ASIO, but have bought a X32 Rack + Dante module and are currently testing it in preparation to moving to it. I checked on our Dante network and some of the devices only support PCM24 so I have everything set to PCM24.
We use DVS in ASIO mode and will try to do some testing later in the week to see what the delay is like and if it is consistent.

Regards,
Mark
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