The short answer
Audio and video take different paths through your equipment, and video almost always takes longer because it has to be processed. When sound arrives before the picture, the fix is to delay the audio — most TVs, soundbars and receivers have an audio delay or lip sync setting for exactly this. Start by turning off the TV’s motion smoothing and switching the picture mode to Game or Filmmaker, because heavy video processing is the most common source of the delay in the first place.
Lip sync problems are uniquely distracting. A small error you cannot consciously identify still makes everything feel subtly wrong, and once you notice it you cannot stop noticing it. The good news is that this is one of the most fixable problems in home video, because almost every device in the chain provides an adjustment for it.
The trick is correcting it in the right place. Adjusting the offset in three devices at once is how people end up with a setup that is perfect on one input and badly wrong on every other.
Where the delay comes from
Audio is cheap to process. Video is not. A modern TV runs incoming video through noise reduction, upscaling, motion interpolation, local dimming calculations and colour processing, and each stage adds time. Meanwhile the audio has been decoded and is ready to go. The result is sound that arrives ahead of the picture.
That is why picture mode matters so much. Motion smoothing is the worst offender because interpolation requires the processor to hold several frames in memory to generate the intermediate ones. Game mode exists specifically to bypass most of this chain, which is why switching to it often fixes lip sync as a side effect.
The second source is the audio path itself. If sound is going out to a soundbar or receiver, that device adds its own processing, particularly when decoding surround formats or applying room correction and virtual surround. Now you have delays on both sides that may or may not cancel out.
Wireless makes it worse. Bluetooth speakers and headphones add substantial latency, often a couple of hundred milliseconds. Some TVs compensate automatically for their own Bluetooth output and some do not.
Finally, the source matters. Streaming apps handle sync internally and generally do it well, but a broadcast signal, a poorly muxed file played from USB, or a stream under network stress can arrive with the error already baked in — and no amount of adjustment at your end will fix a source that is drifting.
Work out whether audio is early or late before you adjust anything. Watch someone speaking straight to camera. If you hear the word before the lips move, audio is early and needs delaying — this is by far the most common direction. If lips move first, audio is late, which usually means a wireless speaker or a processing-heavy audio device.
Cut the video processing first
Before touching any delay setting, reduce the cause.
Turn off motion smoothing — it is called Motion Interpolation, TruMotion, Motionflow, Auto Motion Plus or similar depending on the brand. Then switch the picture mode to Game, Filmmaker or Movie, all of which bypass large parts of the processing chain.
Also turn off noise reduction and any dynamic contrast or clarity enhancement. Check whether the TV has an Auto Low Latency Mode setting and enable it.
Recheck the sync now. On many setups this alone brings it within tolerance, and you avoid introducing a correction that will be wrong when you later change modes.
Decide which single device will do the correction
Pick one place to apply the offset and leave every other device at zero. Corrections stack, and stacked corrections are the reason people end up chasing the problem around their equipment forever.
If everything passes through an AV receiver, correct there. If you have a TV and a soundbar over ARC or eARC, correct on whichever of the two offers a finer adjustment — usually the soundbar. If the TV is the only device, correct on the TV.
Before you start, set the audio delay to zero on every other device in the chain so you know your starting point.
Set the delay methodically
Find the setting: on a TV it is usually Sound > Expert Settings > Audio Delay or Lip Sync. On soundbars and receivers it is Audio Delay, AV Sync or Lip Sync.
Use content with clear, repeated speech straight to camera — a news broadcast is ideal. Increase the delay in steps of about twenty milliseconds, watching for several seconds at each step.
You are looking for the point where it flips from audio-early to audio-late, then backing off slightly. Working past the correct value and coming back is more reliable than creeping up on it, because small errors are hard to judge in isolation.
Once set, check a different app and a different input. A correction that only works on one source usually means the problem is in that source, not in your equipment.
Simplify the audio path
If sound goes to a soundbar or receiver, try bypassing it temporarily and using the TV speakers. If sync is correct on TV speakers and wrong through the soundbar, the soundbar’s processing is the cause.
On the soundbar, turn off virtual surround, room correction, night mode, dialogue enhancement and any sound field processing. Test with a plain stereo or direct mode. These features add real latency and some add a surprising amount.
Check how the audio is connected. eARC and ARC over HDMI handle sync negotiation better than optical, which carries no timing information back to the TV at all. If you are using optical for convenience and have ARC available, switch.
Deal with wireless audio separately
Bluetooth introduces latency that is often too large for a TV’s delay setting to compensate, and it varies between devices.
If you are using Bluetooth headphones with the TV, check whether the TV has a dedicated Bluetooth audio delay setting — many do, separate from the main audio delay. If the delay is still too large, a low-latency transmitter connected to the optical or headphone output will do far better than the TV’s built-in Bluetooth.
Wireless rear speakers on a soundbar system are usually synchronised by the manufacturer and should not need adjustment. If they are out of sync with the main bar, that is a fault or a firmware issue rather than something to correct manually.
Reset the HDMI chain
If sync is wrong on one input only, or appeared suddenly, the HDMI handshake may have negotiated badly.
Turn everything off, unplug the HDMI cables, power everything down at the wall for a minute, then reconnect and power on in order: source devices first, then the soundbar or receiver, then the TV.
Also try a different HDMI port. On many TVs only one or two ports support eARC and full bandwidth, and a device on the wrong port behaves differently.
If you have an older HDMI cable in the chain carrying a high-bandwidth signal, swap it. Marginal cables cause a range of odd behaviour including sync problems.
Check whether the source is at fault
Test the same content through a different app or device. If the delay appears in one app only, it is that app — update it, clear its cache, or reinstall it.
If the sync drifts progressively worse over the course of a programme rather than staying constant, that is a source or file problem, not an equipment one. A fixed offset cannot correct a drift.
For broadcast television, a small persistent error is sometimes present in the transmission itself and will vary by channel. If one channel is out and others are fine, nothing at your end is wrong.
Reading the pattern
Audio early on everything, consistently. Video processing delay. Reduce processing, then apply a single audio delay.
Audio late. Usually a wireless speaker or a processing-heavy audio device. Fix the audio path rather than adding delay.
Wrong on one app only. That app. Update or reinstall it.
Wrong on one input only. HDMI handshake or that source device. Power-cycle the chain and try another port.
Drifts worse as a programme goes on. Source or file problem. A fixed offset will not help.
Correct on TV speakers, wrong through the soundbar. Soundbar processing. Turn off its sound modes and test in direct stereo.
Appeared after a software update. Known to happen. Check for a newer update, and reset the audio delay to zero before re-measuring.
Do not set a large audio delay to compensate for Bluetooth headphones and then forget about it. When you go back to the TV speakers or the soundbar, everything will be badly out of sync and the cause will be far from obvious. Note any offset you set and where you set it.
How much error actually matters
Human tolerance for lip sync error is asymmetric, which is worth knowing when you are deciding how much to chase. We are noticeably more forgiving of sound arriving after the picture than before it — which makes sense, since in the physical world sound always lags light.
Broadcast standards reflect this, allowing a larger margin for audio lagging than leading. In practice, if sound is slightly late you may not perceive a problem at all; if it is slightly early, you probably will.
That has a practical consequence: when you are dialling in a delay and cannot find a setting that feels exactly right, err towards slightly too much delay rather than slightly too little. The overshoot is much less noticeable than the undershoot.
Why did lip sync suddenly get worse after a TV update?
Updates change the video processing pipeline, which changes the delay. Set your audio delay back to zero and re-measure rather than adjusting the old value, since the correct offset may now be quite different.
Should I use ARC or optical for a soundbar?
ARC, or eARC if both devices support it. Optical carries no return timing information and cannot pass the newer surround formats. ARC handles sync negotiation far better.
Can an HDMI cable cause audio sync problems?
A marginal cable carrying a high-bandwidth signal can cause a range of odd behaviour, sync included. It is not the most likely cause, but it is cheap to rule out by swapping in a known-good cable.
Why is sync fine on streaming apps but wrong on live TV?
Streaming apps control both streams and synchronise them internally. Broadcast signals arrive with whatever error the broadcaster introduced, and it varies by channel. That error is not yours to fix.
Does game mode really reduce audio delay?
It reduces video delay by bypassing most of the processing chain, which usually brings audio and video closer together. It is the quickest single change worth trying.
The bottom line
Reduce the cause before correcting the symptom. Turn off motion smoothing and switch to Game or Filmmaker mode, because heavy video processing is what creates the delay in the first place, and a correction set against maximum processing will be wrong the moment you change modes.
Then pick exactly one device to apply the offset in, zero the setting everywhere else, and dial it in with clear on-camera speech, overshooting and coming back. Check the result on more than one input and more than one app — if the correction only holds for one of them, the problem was never in your equipment.
