Hey all,

First, I’d like to say I’m a massive fan of the vMix replay system and have been using it for years now. That being said, I seem to keep encountering the same random issue where all of my replay angles freeze and have missing frames when I play them back.

This is a somewhat rare occurrence, but it happens more often when I run the replay with 4 angles and if I have the quality set above LQ. However, using all these preventative measures only gets me so far, as it still occurs.

My current machine specs are:

AJA KONA 4 SDI PCI-E Video I/O Card

Asus Dual GeForce RTX 4060 Ti

Intel Core i7 14700KF

Corsair Vengeance 32GB

Microsoft Windows 11 Pro

Samsung 970 EVO 500GB M.2 SSD (OS drive)

2TB M.2 SSD (record drive)

MSI MPG Z690 Edge Wi-Fi Intel LGA1700

I input 4 × SDI PAL 1080p50 channels into the session and record all four at times. However, when I have this issue occur, I drop the fourth channel from the replay record and it seems to fix the issue (could be a coincidence).

I take this replay output from this machine into my main vision mixer device via NDI. No other recording is done by this device, and it has pretty much a blank install of Windows with no bloatware.

Here is a snippet of what occurs:
https://imgur.com/a/CBdRkJV
It occurs across all feeds simultaneously and doesn’t ever recover the blank frames, even after stopping the recording.

I can rule out the following:

The issue being machine-specific (at my old company I had the same thing occur at random on a very high-spec ~$30k machine)

The issue being specific to certain versions of vMix

Somewhat rule out camera feeds being dropped momentarily (not 100%, but seems unlikely)

It’s not the KONA card, as I’ve had the same issue with a Blackmagic DeckLink 8 SDI input card

It’s not the session settings or resolutions, as I’ve also run 1080i50 PAL and seen the same issue

All signs point to this being some sort of SSD drive limitation, or possibly blank spaces where vMix splits replay files—unless anyone has any other theories?

What I’m thinking of trying is installing two more M.2 SSDs and recording my three main camera feeds to individual drives, as the recent version of vMix supports this feature and I’m yet to try it.

Any help or feedback would be very much appreciated!

This is something important I need to fix, as this replay setup is used in our competition by our judges to make calls that affect winnings. After two years of this happening, it has finally occurred during a judges’ review.

The motherboard isn't optimal for your configuration.

The 20 PCIe CPU lanes of the i7-14700KF are only allocated to :

PCIe 1 slot = GPU = x16
M.2 slot = SSD (Windows) = x4

You need to change the motherboard to one that allows you to distribute the PCIe CPU lanes across more slots:

PCIe 1 slot = GPU = x8
PCIe 2 slot = AJA Kona 4 = x8
M.2 slot = SSD (Windows) = x4

For example, sticking with MSI:

Z690 Unify
MPG Z690 Force WiFi
MPG Z690 Carbon WiFi
Z690 Unify-X


Since you're only using 4 inputs at 1080p50, you can still optimize your configuration:

Replace the motherboard with an Asus ProArt Z690 Creator
Install a Dual M.2 PCIe SSD Adapter Card in PCIe slot 2
and enable x4+x4 bifurcation on this PCIe slot

On the Dual M.2 PCIe SSD Adapter Card
connect the M.2 SSD for Rec Replay
+ a DeckLink Duo 2 or Magewell Pro Quad SDI card via an M.2 to PCIe x4 riser

The 2TB M.2 SSD also needs to be tested to see if its read/write performance is adequate or if it needs to be replaced.
A good M.2 SSD (PCIe 3.0 x4 or higher) should have no issues with HQ quality recording.

Clean Windows installation
All drivers updates
configure vMix settings
Format the Rec Replay SSD

With this configuration, everything is connected to the CPU PCIe lanes
and there will be no more problems


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