SCENARIO

We are looking mix externally on a Ql5 and ingest that audio back into vMix. The vMix machine has a Focusrite RedNet PCIe Dante card which we are patching to the QL5 with. We would like to play video from within vMix, send the audio from those videos out A bus to the QL5 and then get a full PGM return (with mics, etc...) back into vMix. The QL5 will be the only source in the Master bus.
ISSUES

Using a sync-test video, the video on vMix and the audio coming off the console directly (via speaker connected to console) is exactly in sync (+/- 5ms, but basically perfect). However, when we send the mixer PGM audio back into vMix and then listen to vMix output, it is off by 180ms.
The audio from the console is being ingested into vMix via the RedNet card and using vMix's "audio only" input.
When looking at RedNet control, we can see the beeps in the audio monitoring lights are exactly in sync between the vMix A bus output and the QL5 PGM return to the vMix machine.
It definitely appears to be a vMix issue. To clarify, the video is ahead of the audio, which is the opposite of what we typically see.

QUESTION

What would be causing the delay on the audio-only input to vMix and how can we avoid it?

Sort of.. Spoke with Martin who said it is unavoidable as the buffer size is required. I think it is a rather large buffer. Comes out to about 250ms delay. While I don't consider this to be an actual solution, we run primary and backup vMix systems into a third system that does the actual encoding and also offers gatekeeping and failover switching to the streaming destinations. We add video delay on that system to match up with the audio.

Here is what Martin said:



Not the answer I was expecting.