Audio sync and lip sync test
A flash and a click, fired at exactly the same instant, over and over. If you hear the click before or after you see the flash, your sound and picture are out of step. This helps you work out which way, and roughly by how much.
The test
This test needs JavaScript to run. The explanation and the fixes below still apply, so the page is useful either way.
What you are hearing
Nothing to fix. Below roughly 20 milliseconds nobody can reliably tell them apart.
The usual case. Picture processing delays the image, and the audio path is faster. Reduce the audio delay, or add picture delay if your TV offers it.
Less common. Usually a soundbar or receiver processing faster than the TV. Add audio delay in the TV or the sound system.
Points at Bluetooth speakers or a wireless system, where latency is not constant. A wired connection is the only reliable fix.
What this test can and cannot tell you
This is the test where the honest limits matter most, so read this part.
This works. Telling whether sound leads or lags the picture is something human perception is genuinely good at, and that is the answer you need to pick the right setting.
An estimate at best. You are judging against your own reaction time, and the browser adds its own scheduling jitter between the flash and the click. Treat any number you arrive at as a ballpark to start adjusting from.
Not possible from a web page. A real measurement needs a microphone and a light sensor recording together. Our companion apps will do exactly this with the phone camera and microphone, which is the honest reason they exist.
Expect a false reading. Bluetooth adds 100 to 300 milliseconds of its own latency, and it varies. If you are on Bluetooth you already know the answer, and no TV setting will fully fix it.
Not necessarily. Many televisions apply different processing to the browser than to Netflix or the tuner. A perfect result here does not guarantee perfect lip sync everywhere.
How to fix it
Find the audio delay setting
On most televisions it is under Sound, then something like Audio Delay, AV Sync, Lip Sync or Audio Offset. Adjust in steps of about 20 milliseconds and re-run the test after each change.
Fix it at one end only
If you have a soundbar or receiver, it very likely has its own delay setting too. Set the delay in one device and leave the other at zero, or you will spend the evening chasing yourself.
Switch off motion smoothing
Motion interpolation is one of the biggest causes of picture delay, because the TV has to hold frames back to interpolate between them. Turning it off often fixes lip sync outright.
Try game mode
Game mode bypasses most picture processing, which cuts the picture delay dramatically. If lip sync is perfect in game mode and bad otherwise, the processing was the cause.
Questions people ask
Why is my TV sound out of sync with the picture?
Almost always because the picture takes longer to process than the sound. Motion smoothing, noise reduction and upscaling all hold frames back by tens of milliseconds, while audio passes through comparatively untouched. The sound then arrives first, or the picture arrives late, depending on how you look at it.
How much lip sync delay is noticeable?
Most people start to notice when sound leads the picture by around 45 milliseconds, or lags it by around 125 milliseconds. We are more tolerant of sound arriving late than early, because that is what happens naturally with distance in the real world.
How do I fix lip sync on my TV?
Look for an Audio Delay, AV Sync or Lip Sync setting under the sound menu and adjust in small steps. Before that, switch off motion smoothing, which is the single most common cause. If you use a soundbar, set the delay in one device only, not both.
Can this test measure the exact delay in milliseconds?
No, and we would rather say so. You are judging against your own reaction time, and the browser adds scheduling jitter of its own. It tells you reliably which way the error goes, which is what you need to know to fix it, but a precise figure needs a microphone and light sensor recording together.
My Bluetooth speaker is badly out of sync.
That is expected. Bluetooth adds 100 to 300 milliseconds of latency and it is not constant, so it can drift. Some TVs offer enough audio delay adjustment to compensate roughly, but the only reliable fix is a wired connection or a low latency codec on both ends.
Related tests
Or browse all TV tests.
More apps from 2kit consulting
More apps from 2kit consulting · Made in Germany
