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#1 Posted : Saturday, October 1, 2022 1:00:51 AM(UTC)

Rank: Newbie

Groups: Registered
Joined: 5/2/2020(UTC)
Posts: 2
United States
Location: Austin


We have a workstation PC with a decklink quad 2 capture card installed that is starting to give us issues when adding the sources into vMix on the latest version of 25.

Specifically, when adding more than 6 Decklink Quad sources into vMix, the 7th one causes all of the previously added inputs' audio to start stuttering and popping. Video looks fine, but the embedded audio cannot seem to keep up. We've tested the sources on other devices and have traced it back to this specific PC. I've taken steps such as uninstalling Desktop Video, and reinstalling the drivers at different versions to check for compatibility, along with running the latest Windows Update. Originally the problem started showing after adding a 4th decklink input, but the above software updates have fixed the problem up to 6 inputs. We are now on the most updated version of Desktop Video 12.4 and Windows 10 21H2. These are 1080p59.94 video sources.

This seems to be like it's a PCIe bandwidth issue, but it's hard to track down where the bottleneck is coming from. We have another identical PC build that doesn't have this issue.

The PC build:
MSI Gaming Intel X299 PRO
Intel Core i7-7800x
MSI Gaming GeForce RTX 3080 LHR 10GB
Samsung 970 EVO Plus SSD 2TB (Storage)
Samsung 970 EVO Plus SSD 500GB (Boot)
Corsair Vengeance LPX 32GB
ARCTIC Liquid Freezer II 240
Corsair RM-750
Blackmagic Decklink Quad

Any thoughts or recommendations to diagnose would be greatly appreciated, thanks in advance!
#2 Posted : Friday, December 16, 2022 1:36:22 AM(UTC)

Rank: Newbie

Groups: Registered
Joined: 12/16/2022(UTC)
Posts: 1
Location: munich

Hi jb,

sadly I don't have Solution for you but can share similar experience.

But I'd like to as you: have you found any solution or cause since then?

We upgraded to a new PC and since then expirencing massive drop outs of the embedded Audio on a Decklink SDI Output (Decklink 8k Pro).

I can't list all the many Things we've tried so far - its a long list, hardware- and software-wise. But NOTHING changed. Most likely I will elaborate on a separate Post here.

But, any Solutions on your side?

Thank you, Chris
#3 Posted : Saturday, December 17, 2022 7:49:15 AM(UTC)

Rank: Newbie

Groups: Registered
Joined: 12/17/2022(UTC)
Posts: 3

Thanks: 1 times

got something maybe going the same direction, we have trouble with our system too. z690 MB with a 13th gen Intel + 3070ti. Local Audio Recordings from vmix are fine, but as soon as we start a recording via the decklink card going to a hyperdeck or external PC, Audio gets choppy. gets worse by the minute. tried other GPUs, reinstalled win 10 completely and tried adding/removing drivers one after another until we can see any difference, no difference what so ever. Even with only the basic drivers nothing seems to solve change the outcome -.-Lanes should be fine, but we are without any clue at the moment what could be causing the problem.
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