Lip Sync Test: Check Audio and Video Sync on Your TV

How to run an audio video sync test on a TV

A lip sync test needs to play on the screen and through the speakers you actually watch with, so the delay of the whole chain is included. There are three common ways to get this page onto a TV. Pick the one that is closest to how you normally watch.

In the TV’s own web browser

Many smart TVs have a browser. Open this lip sync test there and use the remote’s arrow keys to move the slider. This measures the TV’s picture processing together with its speakers or whatever sound system is connected to it. Browsers on TVs vary a lot; if the beep does not play, use one of the other ways.

From a computer over HDMI

Connect a laptop to the TV with an HDMI cable and set the TV as the sound output. This is usually the most dependable option, because the computer’s audio clock drives both the flash and the beep, and the TV, soundbar or receiver adds its delay as it would for any other source.

By casting or screen mirroring

Casting a browser tab or mirroring a phone screen works, but the result includes the delay of the casting link itself, which a normal streaming app may not have. Use casting to check what you will experience while casting, not to judge the TV on its own.

On every path, set the TV to the picture mode you watch in. Game mode, film mode and the various motion settings can each change the picture delay, so a measurement only applies to the mode you used.

Measure it precisely with a slow-motion video

Judging sync by eye is quick but has an error of tens of milliseconds. A slow-motion video of the screen removes most of that judgment. Many phones can film at 120 or 240 frames per second, and a frame count turns the gap between flash and beep into milliseconds.

1. Press “Full-screen pattern for filming”. The pattern flashes white once per second with a beep, shows a frame counter and a sweep bar so you can see the screen refresh.
2. Film the screen with the second phone in slow-motion mode for about ten seconds, close enough to hear the speaker clearly.
3. Open the video in an editing app that shows the sound waveform and step through it frame by frame.
4. Find the first frame where the screen turns white, then the frame where the waveform shows the beep starting. Count the frames between them.
5. Enter the count and the frame rate below. Repeat for three flashes and use the median.

If the beep starts before the flash in the video, the sound is early; record the result as negative. One frame at 240 fps is about 4.2 ms and at 120 fps about 8.3 ms, so this method is limited mainly by how cleanly you can see the start of the beep. Phones can also record sound and picture with a small offset of their own, so treat the figure as a careful estimate rather than an exact value.

Comparing ways to measure lip sync

For deciding whether to change a setting, the slider is usually enough. For setting an exact delay value on a receiver, the slow-motion method is worth the extra minutes.

How to fix lip sync on a TV, soundbar or AV receiver

Use the sign of your result to choose the fix. Menu names vary by brand, so look for words such as AV sync, audio delay, lip sync or audio offset.

• Sound early (negative result). Add audio delay in the device that produces the sound – the TV for its own speakers, otherwise the soundbar or receiver – by roughly the amount you measured, then test again.
• Sound late (positive result). Most audio delay settings can only hold the sound back further, so first remove delay from the sound path: turn off extra sound processing or virtual surround on the soundbar, and switch the TV to game mode if the picture is also part of the problem. Some devices accept a negative value or a “sound ahead” option; if yours does, enter the measured amount.
• Through HDMI ARC or eARC. HDMI has an automatic lip sync feature that lets the TV tell the sound system how much it delays the picture, though not every device uses it. Check that ARC or eARC and any automatic lip sync option are switched on in both the TV and the soundbar or receiver.
• Passthrough or bitstream. Setting the TV’s digital audio output to passthrough sends the sound to the soundbar or receiver without the TV decoding it first, which can change the timing. Try both passthrough and the TV’s own processing and measure each.
• Correct in one place. If the TV, the soundbar and the receiver all have delay settings, use one and set the others to zero, so the corrections do not add up.

Watching with wireless headphones? The Bluetooth latency test shows how much they add, and the audio delay test gives a quick overall reading on any device.

Your privacy

The tests on this page never touch your microphone. They play beeps and show flashes, and every calculation happens in your browser. Nothing is uploaded and there is nothing to sign up for. We only count anonymous events such as “a test finished with a result between 100 and 200 ms”, never the exact number.

Details are in the privacy policy.