Fixing OBS Audio Sync with a Browser-Based Offset Measurement

OBS Audio Sync Fix: Measure and Correct Webcam Lip-Sync Offset

The fastest OBS audio sync fix is to measure the actual timing gap instead of guessing. OBS audio sync problems have one root cause: the video and audio paths take different amounts of time. Video from a USB webcam travels through the camera's ISP, a USB host controller, and a browser or OBS video decoder before landing in the timeline. Audio from a USB microphone follows a shorter path through the audio class driver and OBS audio stack. The difference between these two path lengths is the offset you measure and correct.¹

Before adjusting any settings in OBS, measure the actual offset with the 5-clap test on this page. Getting a measured number eliminates the guesswork of trial-and-error OBS adjustments. The browser test uses the camera and microphone inputs you choose through getUserMedia, which prompts for permission before the page can receive media tracks.² Typical USB webcam setups often show audio arriving before video, but the exact value changes by machine, driver, and USB topology.³ Once you have the measured value, entering it in OBS's Sync Offset field takes under 30 seconds.

How to measure the offset before touching OBS

Run the 5-clap test on this page with your actual streaming microphone and webcam selected as the inputs. Each clap generates one timestamp pair. After five pairs the tool displays an average offset with a direction label and a pre-calculated OBS Audio Offset value. Write down or copy that value before opening OBS; the measurement disappears when you navigate away from the page.

For the most accurate reading, run the test with OBS closed. When OBS is open and capturing the same camera, it competes with the browser for the video feed, which can add jitter to individual frame timestamps and inflate the spread across your five clap readings. Measure in the browser alone, then open OBS and apply the value.

The most accurate measurement comes from running the five-clap test with OBS closed. When OBS has your webcam open as a video source, it shares the camera hardware with the browser, adding scheduling overhead to the video frame delivery. The browser must negotiate frame access with OBS on every capture cycle, which increases per-frame variance and widens the spread across your five clap readings. Close OBS, run the browser test, record the value, then open OBS and enter the correction.

Matching OBS source and microphone pairing

Make sure the OBS value you measured corresponds to the same webcam and microphone source you use in the scene. If your scene has multiple microphones, the Sync Offset column applies to one source at a time. Enter the value on the microphone row that feeds your stream, not on desktop audio, game capture audio, or a secondary mic. Taking an extra moment to verify the source name in the browser dropdown matches the OBS source name prevents the common mistake of correcting the wrong audio path and wondering why the sync still looks off.

If your OBS setup has both a webcam audio source and a desktop audio source, the Sync Offset column is per-row, not per-scene. Choosing the desktop audio row by mistake shifts only the system sound, leaving the mic path that users actually hear unchanged. Matching the browser dropdown label to the OBS source name is the quickest way to avoid that mistake.

Entering the offset in OBS Studio

In OBS Studio, open the Edit menu and select Advanced Audio Properties. The table lists every audio source in your current scene collection. Find your microphone source in the list and click the Sync Offset (ms) column cell for that row. Enter the OBS Audio Offset value this tool displayed, then press Tab or click another cell to confirm the value is accepted before closing the dialog.⁴

OBS implements that field as a millisecond sync offset for each audio source, with the source file showing a numeric input range from -20000 ms to 20000 ms and converting the entered value to nanoseconds before applying it.⁵ A positive value delays that audio source, which is the usual correction when audio arrives before video. A negative value lets OBS use buffered audio to move the source earlier relative to the rest of the mix, which is useful when video arrives before audio.⁴

After entering the value, close Advanced Audio Properties and record a 10-second test clip. Play back the clip and watch whether your clap sound aligns with visible hand impact in the footage. If the alignment looks correct in the test clip but your live stream still shows desync, check whether OBS is applying the offset to the recording output but not the streaming output, since OBS maintains separate output paths that can have different sync states.

Confirming the saved OBS offset

After entering the OBS Audio Offset value, verify it saved correctly by closing Advanced Audio Properties and reopening it. OBS saves the scene collection when that dialog closes, but confirming the value on reopen protects you from a silent entry mistake.⁶ If the field shows the correct value on reopening, the correction is active. Record a 10-second test clip, play it back, and clap once visibly and audibly in the clip to check alignment.

When to re-measure instead of reusing an old value

Your OBS sync offset is not permanent. Re-measure whenever you add or remove a USB device that shares the webcam's host controller, because USB bus load changes video frame timing.³ Driver updates from Logitech, Elgato, or your USB chipset vendor can also shift the pipeline latency, so verify the old value after any driver or firmware update.

Consequently, the safest workflow is to measure at the start of each streaming session rather than relying on a value from a previous session. The 5-clap test takes under two minutes and gives you confidence that your stream will be in sync from the first minute of content, not just the first session after you set up the offset.

When to re-measure after USB or driver changes

Several events require re-measuring rather than reusing the saved OBS offset. Adding or removing any USB device that shares the webcam's host controller changes the bus load and shifts the video frame timing. Updating the webcam firmware through Logitech G HUB, Elgato Camera Hub, or Razer Synapse can shift the pipeline latency, so get a fresh measurement before you trust the saved value. Switching to a different USB port on the same machine also changes the offset if the new port is served by a different host controller. The five-clap test takes under two minutes; run it again whenever any of these changes occur to keep your OBS correction accurate.

When to use this

Confirm whether OBS needs a positive or negative Sync Offset when recordings show audible lip-sync gap, when a viewer reports your audio is slightly ahead of or behind your mouth movement, or when you have changed your streaming hardware setup and want to verify the sync before going live.

Examples