Vmix Forum |work| -

Title: Audio out of sync (delayed) on NDI inputs only – vMix 27

Username: StreamTech_24

Posted: Today at 04:23 PM

Category: Audio / NDI

Hi everyone,

I’ve run into a strange issue that just started today. I’m running vMix 27 Pro on a Ryzen 9/64GB RAM/RTX 4070 machine. My main camera is connected via SDI (fine), but my secondary Zoom call (coming in via NDI Tools Screen Capture) has a noticeable audio delay – about 300-400ms behind the video.

What I’ve tried:

• Updated NDI Tools to v6
• Set audio delay on the NDI input to "0ms" (tried negative values – doesn't work, won't go below 0)
• Checked buffer settings in vMix (NDI buffer is at "Auto" – tried "Low" and "High" – no change)
• Monitored via vMix’s audio meter – audio waveform is visibly late compared to the clap test

What works:

• If I use the same Zoom source via NDI Studio Monitor directly – audio is perfect.
• Local files and SDI sources are perfect.

Question:
Is there a hidden setting in vMix to force NDI audio to "real-time" or bypass the internal buffering? Or could this be a Windows audio driver conflict with vMix’s low-latency mode?

Any insight would be hugely appreciated. Thanks!

Reply from Moderator (vMix Team) – Example:

Username: admin_martin

Posted: Today at 04:45 PM

@StreamTech_24 – Thanks for the detailed report.

First, check your vMix Audio Settings (gear icon next to master volume):

• Is "Audio Interface" set to your main output device (not "Microsoft Sound Mapper")?
• Try toggling "Use Internal Audio Processing" OFF/ON.

Second, for NDI specifically:

• Right-click the NDI input → Audio → Make sure "Use embedded audio" is selected (not "Separate audio input").
• Try setting NDI Buffer under "Advanced NDI Settings" (in vMix settings) to 10ms instead of Auto.

Finally – negative audio delay isn’t supported in vMix. You would need to delay the video to match the audio instead. Add a video delay filter (Filter → Video Delay) to the SDI source so both align.

Let us know if that solves it.

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