EMEET Nova 4K A/V Sync & Latency Test

EMEET Nova 4K A/V Sync Test: Measure Audio Offset for OBS and Meetings

Confirm the active resolution before you trust any Nova 4K sync number. EMEET Nova 4K is a 4K USB-A webcam with PDAF autofocus, dual noise-cancelling microphones, and a 73° field of view. It can default to 1080p on some systems, so confirm the active resolution before you treat the offset as production-ready.¹ Measure the camera-to-microphone pair you actually use, because the built-in mic and an external USB mic follow different audio paths.

The five-clap test gives you a browser-level offset for the active camera mode, audio endpoint, and USB topology. Use that measured value instead of a generic Nova 4K offset, because resolution, app processing, and the selected microphone can change the timing path.

Specifications¹

Connection and browser setup

Connect the Nova 4K to a USB-A port and keep the same USB topology for all five readings. The Nova 4K is documented as a 4K/30fps PDAF webcam with a 73° field of view and USB-A connectivity.² Grant camera and microphone permissions in Chrome when prompted; the browser receives local media tracks only after you approve the request.³

Select the camera video input and choose either the Nova 4K's built-in mic or your external microphone in the audio input field, depending on which pairing you use for streaming. If the same camera is moved to a different USB controller, hub, or port, run the five-clap test again because USB bandwidth is shared across the host controller and device tree.⁴ The Nova 4K's USB-A connector means it can plug into any standard port, but on machines where all USB-A ports share a single internal host controller, moving the cable between ports may not actually change the bandwidth situation.

The Nova 4K works as a UVC device with the system-supplied driver, so the browser can access the camera without a vendor-specific driver.⁵ If you use EMEETLINK or another processing app, measure with the same video and audio settings that your streaming setup will use. Running the test with the full software chain active, including any vendor processing app, keeps the measured offset honest about the total delay your actual pipeline introduces from capture to browser delivery.

Built-in mic versus external mic pairing

The microphone selection changes the audio side of the measurement. If you stream with a USB microphone, select that microphone during the test and use that value in OBS. If you stream with the Nova 4K's built-in microphone, select the Nova 4K audio entry instead. Do not measure the built-in mic and then apply the result to an external mic path; those are two different audio endpoints.

If you switch microphones between claps, the reading toggles between the built-in mic and the external mic path. Each path has a different delay, so the average no longer represents either endpoint cleanly. Stick to the same input for all five claps and use that specific offset entry in OBS.

Verifying the Nova 4K OBS correction

After entering the OBS Audio Offset value, record a short clip and clap once near the center of the frame. The clap sound should land on the visible hand impact. If the sound leads the image, increase the Sync Offset by 5 to 10 ms; if the sound trails the image, reduce it and test again. Repeating this verify-and-adjust cycle two or three times typically brings the residual error below one frame at 30fps, which is the practical target for production streaming.

Common A/V sync issues with this model

The Nova 4K's image and audio paths are sensitive to the active capture mode. A 4K stream, a 1080p stream, the built-in microphone, and an external USB mic can each produce a different offset, so keep those settings fixed while you collect the five readings. Changing any of these variables between claps introduces a new variable into the measurement, which makes the five-reading average less meaningful as a correction value for your specific streaming configuration.

If the readings jump around, check the active resolution, USB connection, and audio endpoint before changing OBS. The five-reading average is useful only when each reading comes from the same camera mode and the same microphone path. Re-run the test after switching resolution, moving the USB cable, or changing the selected audio device. The Nova 4K's PDAF autofocus system can also introduce small timing variations if the focus position shifts between claps, so allow the autofocus to settle before starting the test and avoid moving forward or backward during the five-clap sequence.

Interpreting a wide five-reading spread

A wide spread usually means the measurement conditions changed between claps. Look for autofocus movement, resolution changes, background CPU load, or an audio endpoint switch before you treat the average as final. If the spread persists, record two five-reading sessions and compare their averages before copying one value into OBS. A consistent average across two separate sessions gives you much higher confidence that the offset reflects your true hardware timing rather than a single anomalous reading influenced by a momentary CPU spike or USB contention event.

What the test covers

Five clap pairs average the video-to-audio offset for the active Nova 4K capture mode and the selected microphone. The average is useful when the camera resolution, USB connection, and audio endpoint stay the same across all five readings. Because the Nova 4K can default to 1080p on some systems even though it is a 4K camera, always verify the active resolution in the browser preview before trusting the measurement; a 1080p browser stream and a 4K OBS capture represent two different processing paths through the camera.

Building on this, the OBS Audio Offset value displayed reflects either the external mic or the built-in mic pair you selected. The two pairings can produce different offsets, so use the measurement that matches your streaming setup.⁶ The Nova 4K's built-in dual noise-cancelling microphones follow a different internal audio path than an external USB microphone, and the built-in mic signal passes through the camera's own audio processing before reaching the browser, which can add a few milliseconds compared to a direct USB microphone connection.

Keep two OBS Sync Offset entries in your notes if you switch between the Nova 4K's built-in microphone and an external USB microphone. Label each saved offset with the pairing it came from, then verify the correction with a short recording before going live. If you use the built-in mic for quick calls and an external USB mic for streaming, having both values saved means you can switch between setups without re-measuring each time.

EMEET's own user manual confirms the Nova 4K's video resolution can default to 1080p in some applications, with 4K requiring a manual switch in your camera software, and separately documents EMEETLINK's brightness, contrast, and saturation controls as active per-frame adjustments.⁷ Ruling out the Nova 4K's silent 1080p fallback matters as much as closing EMEETLINK for a clean baseline, since either one alone can throw off the number you paste into OBS.