After a (forced) Windows update two weeks ago, the audio and video on our stream gradually drift apart. Also, one of my monitors no longer turned on. I felt that my RTX3080 was at the max of it's capabilities, so I upgraded to a RTX 4070Ti Super. Good news is, the monitor is working again, bad news is that the gradual drift is still present (the audio gradually happens before the video...you hear the clap, then you see the clap)

The PC has:
- Vmix 27.0.0.72 x64
- Resizable BAR enabled
- Power Management Mode is set to Prefer Maximum Performance
- GeForce Experience is NOT installed
- vMix is registering the new card as the Graphics Adapter.


At present we have a total of 45 inputs that can basically be put in three categories:
- video feeds (one SRT, one browser source, one desktop cam going through an elgato HDMI to USBc Adapter)
- desktop windows - several browser windows and weather programs. All but one using Local Desktop Capture/WindowsGraphicCapture. The last one needs Local Desktop Capture/DWM
- graphics - some movies with alpha channels, several browser overlays, one uses a Lottie file

All inputs are set to 30fps, other than I suppose a browser source, which I'm unsure what that fps is (we display another persons stream on ours with permission, though it's not ideal to use it this way)


This has worked really well for a long time. It seems like the 4/1/24 update of Microsoft Visual C++ might be responsible?


Anyway, any ideas? Thanks very much!!



**Case Fans :** Default Case Fan

**Processor :** AMD Ryzen 9 7900X Processor (12X 4.7GHz/64MB L3 Cache)

**Processor Cooling :** iBUYPOWER 240mm Addressable RGB Liquid Cooler - Black - [Free Upgrade to iBUYPOWER DEEPCOOL GAMERSTORM RGB 240mm CASTLE 240EX Liquid Cooler]

**Memory :** 32 GB [16 GB X2] DDR5-6000MHz Memory Module - Corsair Dominator (RGB LED)

**Video Card :** NVIDIA GeForce RTX 4070Ti Super - 16BG GDDR6X

**Motherboard :** MSI PRO X670-P WIFI - Wifi 6E, ARGB Header (2), USB 3.2 Ports (1 Type-C, 6 Type-A), M.2 Slot (3)

**Power Supply :** 850 Watt - 80 PLUS Gold Certified PCIe GEN 5

**Primary Storage :** 4TB WD Black SN850X M.2 PCIe Gen 4 NVMe SSD -- Gen 4 Read: 7300 MB/s, Write: 6600 MB/s, Gen 3 Read: 3500 MB/s, Write: 3500 MB/s

**Secondary Storage :** 1TB WD Blue SATA SSD -- Read: 545MB/s, Write: 525MB/s

**Media Card Reader / Writer :** Kingston USB 3.0 High Speed Media Reader

**Sound Card :** 3D Premium Surround Sound Onboard

**Network Card :** Onboard LAN Network (Gb or 10/100)

**Operating System :** Windows 11 Home w/ Windows Recovery USB - (64-bit)

We have been facing a similar problem, with Titanium Reference System Build running Window 10, and running two NDI HD Cams in a feed to YouTube. I can post detailed system specs later if needed. The system was built in 2020.

About a year ago, our system began to randomly drift during the stream where the video is suddenly way behind the audio. Some weeks it is perfect for the full 90 minutes. Other weeks it drifts and then resyncs with a camera transition. Sometimes nothing works short of stopping VMIX and relaunching it.

One key issue that can occur, is that VMIX commands to pan or zoom the camera can become very delayed during the sync drift time. This is why I think something is interfering with VMIX's prioritization of the CPU and GPU. But I have not found the culprit.

The system seems entirely stable other than these random drifts. There is no jerkiness in frame rates or other issues.

• Our system rarely shows more than 20% GPU load.
  
• We pay for a 30 MBPS upload speed which is consistently available when tested and the record and stream buttons stay green throughout.
  
• I have tested the Ethernet cables, swapped them, with no improvement.
  
• Reviewed system settings, killed TSR's to no avail

I suspect something is going on with some background function of either Google or Microsoft. I have done my best to kill OneDrive and stopped using/syncing Google Drive which caused no problem before.

I have been thinking about hardware fixes, but my sense is that there is some errant program installed. Perhaps a fresh windows install is a better first attempt? Should I stick with Windows 10 or shift to Windows 11?

What would you check first that I haven't mentioned (or recheck if I did). Thank you!

Hi BoxMan_Actual,

I am curious! What was the program?

Understood about best practice, and we will try that but also if there is a known program conflict, perhaps we could avoid that one altogether?

Thank you!

Yes, we still have an issue too. In our case 1 camera developed a lag and the ptz control would have a several second delay at the same time. Transitioning between cameras had no effect.

The problem seemed to correct itself after about 5 minutes. However, the other camera never had a delay at all!