When the sound isn’t in time with the video you’re watching it might take a while before you notice. But once you do, it’s impossible to ignore and you’ll want to find a solution straight away.

Here’s the bad news: there are lots of things that can cause lip-sync issues, but hopefully the tips here will isolate the problem and – hopefully – fix it for free.

Video sync problems on your TV

Streaming

If you’re streaming video from Netflix or another service and you haven’t had problems with out-of-sync audio before, then it’s likely something has gone awry with the stream. Simply stop the video and, if necessary, exit the player you’re using. You can also unplug your set-top box for 30 seconds to reset it.

Restart it and resume the video and you’ll probably find the problem is fixed.

I just got a new TV

If you’ve just bought a new TV, it could be input lag that’s the problem. This terms simply means that the TV takes a bit of time to process each frame of video to improve its quality before it’s displayed, so you hear the sound before the video.

A slight delay may not be a problem for speaking, but for sound effects such as gunshots, it can be very noticeable.

To test this, try to switch to the TV’s Game Mode. This should disable the image processing and remove any delay and put video back in sync with the audio.

Set-top box

If you notice the problem when watching video from any of your set-top boxes, it’s fairly clear that it’s the TV at fault.

However, if it’s only an issue when you use your Blu-ray or DVD player, or a Sky or Freeview box, then you’re already close to isolating the problem.

It may the box itself, but if you’ve routed the sound through a soundbar, AV receiver or another speaker system, it could be that causing the mismatch.

Most AV receivers have a setting where you can alter the lip-sync delay so it matches the video perfectly. Some sound bars also have the option.

Buying an AV receiver can also be a solution to video sync problems thanks to the adjustment on offer, but that’s not ideal if you want a free fix.

How do I use lip-sync settings to get the video in sync?

If it’s obvious that the audio is playing ahead of the video, then you may be able to just guess how much delay to introduce. Or just do it by trial and error using whatever settings are available on your TV, AV receiver or other speaker system or set-top box.

The more precise way is to play an audio-video sync video such as this useful one on YouTube.

Most smart TVs can play YouTube videos, so it shouldn’t be difficult to do this. The video plays a ‘chirp’ when the rotating bar is exactly at 0ms.

How to fix video sync problems

Just look and see where the bar is pointing when the sound plays: this tells you how much of a delay there is.

And if it’s your sound system causing the problem (maybe because you’re using a Bluetooth speaker) it will also tell you how late the sound is arriving.

What if I’m using a laptop or PC?

You can experience similar video sync problems in Windows. Diagnosing what’s causing the problem is a relatively similar process to your TV and AV gear, though.

Try playing the video in another app, or in another web browser if you’re streaming it. That should tell you if it’s the app or browser.

How to fix video sync problems

VLC is one of our favourite free video players, and it offers great control over audio / video sync. When watching a video you can press j or k to adjust the audio delay by 50ms on each press.

If you’re watching Netflix, it’s possible that it’s still using the Silverlight plugin, rather than the HTML5 player, and this is known to cause lip-sync problems.

Alternatively, check in the Control Panel under Sound and make sure no processing or effects are enabled which could cause a delay in audio.