How to Sync Audio and Video in vMix

Before you start

Audio and video sync in vMix is handled locally in the vMix application on your computer. You do not need an online service or account. The main values to check are the per-input Delay value under Audio Settings and the sync offset for each capture source. Keep a short test clip handy so you can compare lips, claps, or visible sound events against the waveform.

Before changing anything, identify which direction the timing is wrong. If sound arrives before the picture, increase the audio delay for that input. If sound arrives after the picture, reduce the audio delay or look for delay introduced by the capture source, processing, monitor, or encoding path. Work on one input at a time so the correction can be reversed easily.

Step-by-step instructions

Use a short test signal that creates a clear visible and audible event, such as a clap or a sync slate with a beep. Position the test source in the frame so the movement is easy to watch.

Open vMix and locate the input in the main input list. Select the input, then open its settings. The exact location depends on the input type. For many camera and media inputs, start with the gear icon or right-click menu for the selected input.

Go to the Audio Settings area for that input. Find the Delay control. vMix measures this value in milliseconds, so a small change is often enough. Adjust the value while playing the test clip or while watching the live source.

If the issue affects an input device such as a camera or capture card, check whether the audio is arriving through the same device or through a separate audio input. An external audio device with its own processing can introduce a different offset than the camera picture. Route both through vMix when possible so the input delay setting controls the relationship.

For media files that are already out of sync, a per-input delay may not be enough if the offset drifts or changes during playback. In that case, test a short section and use the same delay value only when the drift is consistent.

When the input is a webcam, capture source, or screen capture, compare the input with the computer's default monitoring path. Monitoring through external speakers or a display with its own processing can make the result look delayed even when the vMix timeline is correct.

Make the final adjustment while monitoring the output that viewers will actually receive. For a stream, monitor the stream output path when practical. For a recording, record a short test and play that file back instead of judging only the live program monitor.

Check the output

Record a short test with the current settings and play it back in a normal media player. Watch the clap or beep several times. If the audio is consistently early, increase the input audio delay. If it is consistently late, reduce the delay.

Check both live monitoring and the recording. A sync correction that looks correct in the vMix preview can still appear wrong in the recording if the encoding path, file container, or player adds latency. Use the recorded file as the final check when the recording is the deliverable.

For streaming, watch the stream on a separate device when possible. Some player apps and browsers buffer audio and video differently. A small offset that appears in the player may not be present in the recording, so avoid changing vMix based only on a player before confirming the issue in another output.

Common problems and next steps

A mismatch between the audio input level and the expected output is not the same as a sync problem. If the audio is present but hard to hear, check the input level, background noise, and gain before adding delay. Adding delay to fix low or noisy audio will not solve the actual issue.

Differences in sample rate between audio devices can produce timing problems or audible artifacts. Where possible, use the same sample rate for the input device and the vMix audio configuration. If the audio is attached to a capture source, check the device's own audio settings as well as the vMix input settings.

Frame rate and encoding settings can also affect perceived sync. A capture source running at a very low frame rate may look delayed because the picture updates slowly, even when audio and video are correctly placed. Check the capture source settings and the recording format before making a large audio offset change.

For streams, a high bitrate or limited upload can cause buffering that looks like sync drift in the player. Record locally at the same time as the stream test. If the local recording is in sync, the problem is more likely in the streaming path, player, or network, not in the vMix input timing.

When the source drifts during a long session, pause the live correction and test a short segment. A fixed delay value works for a consistent offset. Gross drift may require replacing the media file, reseating the capture device, or matching device clocks before further vMix adjustments.