I have been using Vmix for about a year now. Recently I have had to delay 3 of my inputs to line up with a GoPro to NDI input that has a one second delay that I can't fix.

The problem is that I find variations in timing once I insert any delay on my inputs. Meaning, the bar in my test clip should hit the center marker and beep. In Vmix, when I add delay to my inputs to line the cameras up with my video, the beep happens at random different places. Not the same place every single time. Off by X amount means it the mark should always show and beep with the same delay. At times this looks like the video slows, and then speeds up to ”catch up”.

My production:
Virtual DJ video feed into Spout - Spout to NDI - NDI into Vmix <- added 1 sec delay to this Vmix input
Audio out on the mixer and plugged into a sound card line in <- added 1 sec delay to this Vmix input
USB Webcam into vmix <- added 1 sec delay to this Vmix input
GoPro 8 RTMP into ActionCam to NDI - Into Vmix <- Zero Vmix delay, because 1 sec delay that I can't avoid

You can forget the timing of all the inputs for a moment. I play the timing clip just in Virtual DJ against the Audio line from the mixer and they are always in sync. I check the Vmix headphones and I can also confirm that.

Then I make visual cue gestures in each camera, to the beeps heard to figure out the camera timing. Only when I add dealy in Vmix do I see inconsistent timing cues. Beeps and marks happening at different timing. If I watch just the playback of the timing clip in VDJ, I can now see it slow and speed up like it is buffering. Again, that does not happen when all the Vmix inputs have 0 delay.

Does anyone else have experience with delaying inputs and still getting consistent playback? We are only talking about 1 second delay on 3 inputs. The CPU is between 15-20% max. Win 10, 32 gb ram, i9, gtx2070 (latest Studio drivers), 3 internal SSD's. 1 year old PC built for doing live video.

The GoPro can broadcast directly to RTMP. ”Action Cam 2 PC” is the app on my PC that receives RTMP adapts to NDI.

But this problem happens without any of that even connected. The GoPro is just the only thing that can’t be real time. I have to delay everything else out to line up with that camera.

My tests were even simpler to isolate the issue. The only thing that fixes the Vmix inconsistent playback speed is removing the delays.