Fix audio and video sync in OBS

First: check whether the offset is fixed or grows

Record two minutes locally in OBS (not a stream) and clap once, sharply and in view of the camera, at the start and again at the end. Play the file back.

If the clap’s sound and picture are apart by the same amount at both ends, the offset is fixed: measure it and set it once, below. If the gap is bigger at the end, the offset grows over time, and a fixed delay will only hide it for a while: go to when the gap grows instead.

Measure the offset with the clap

Open the recording in any player or editor that steps one frame at a time. Find the frame where your hands meet, then find where the clap’s sound starts, and count the frames between them.

Turn frames into milliseconds by the recording’s frame rate: at 30 fps one frame is about 33 ms, at 60 fps about 16.7 ms. Six frames late at 30 fps is about 200 ms. Note which comes first: the sound or the picture. The audio sync calculator does the sum and names the OBS control for your direction.

Set it in OBS

Sound before picture (the usual case with a camera through a capture card): delay the sound. In the Audio Mixer, open the menu of the microphone (the three dots or a right-click) and choose Advanced Audio Properties. Type the measured value in that microphone’s Sync Offset (ms) column, which goes up to 20,000 ms. A positive number makes the sound later.

Picture before sound: delay the picture instead. Add a Video Delay (Async) filter to a webcam or capture-card source (up to 20,000 ms), or a Render Delay filter to other sources (up to 500 ms), and set the measured milliseconds there. Typing a negative Sync Offset is not a dependable fix.

Sync Offset changes the stream and the recording, not what you hear through audio monitoring, so judge the result in a new recording, never in your headphones.

Retest: one recording at your normal length

Record again for as long as you normally stream, with the game, camera and every other device running, and clap at the start and at the end. Both claps lined up means the fix holds. Save the value with the mode you measured it at: changing the camera’s resolution, frame rate or the capture card’s mode can change the delay. The pre-stream checklist keeps this test in your routine.

When the gap grows

A gap that grows during a session comes from a clock or from lost frames, not from a delay you can type in once. Check these in order:

• Sample rates: set OBS (Settings, Audio, Sample Rate) and every playback and recording device to the same rate, usually 48 kHz. On Windows it is under each device’s Properties, Advanced, Default Format.
• Dropped and lagged frames: a picture that loses frames falls behind the sound. Check OBS’s Stats window and follow dropped frames and encoder overload.
• Unstable USB: a camera or capture card that reconnects or shares a busy controller can slip. See USB bandwidth for cameras and capture.
• The same sound twice: two routes of one microphone or game sound feel like a sync error. Remove the duplicate first; double audio in OBS shows the usual case and OBS audio routing the whole map.

When only the stream is out of sync

If your local recording is in sync and the platform’s replay is not, the shift happens after OBS. Run a test stream, compare its replay with a local recording made at the same time, and check the platform’s stream health messages before changing anything in OBS.

Questions

Why does my capture card make the video late? The card has to receive and convert each frame before OBS gets it, while a USB or XLR microphone reaches OBS almost directly. The amount depends on the card and mode, which is why you measure rather than copy a number.

My Bluetooth headphones are out of sync with the picture. Is my stream? Not necessarily: Bluetooth adds its own delay to what you hear. Judge sync in a recording played through wired headphones or speakers.

Equipment for these connections

Start with the kind of gear you’re missing, and read its full profile before adding it to your setup.

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