Lip sync is the timing relationship between a picture and its associated sound. Speech provides a familiar cue because viewers can compare mouth movement with the voice, but the same relationship matters for impacts, instruments and other events. A fixed mismatch means one component consistently leads or lags the other by roughly the same amount. Delay can arise in decoding, buffering, picture processing or audio output. The symptom does not identify which stage is responsible, and an audio-delay control cannot solve every possible direction of mismatch.
Lip sync and Subtitle timing
Subtitle timing relates text to media; lip sync relates audio to pictures.
Follow the timing through the route
Television picture enhancement can delay video, while receivers and wireless headphones can delay sound. A system may compensate automatically, but support and results vary. Changing the output route or picture mode can therefore change synchronization without altering the source. Check the exact combination used during the problem rather than relying on a delay value that worked for another input.
Direction determines the adjustment
If sound arrives before the corresponding picture, delaying audio may help. If sound is already late, adding more audio delay makes the mismatch worse. Some systems can delay video or offer other compensation, while others cannot correct that case fully. Positive and negative labels differ between players, so verify the effect of a small adjustment instead of assuming its direction.
Separate fixed error from drift
Observe a clear speech or impact moment near the start and again later. A similar error suggests an offset; an error that grows points toward drift or timing discontinuities. Compare television speakers with the external audio path. If only one programme is affected across routes, source timestamps or production synchronization become stronger possibilities than a universal device setting.
An illustrative example
A presenter’s lips move slightly before the voice on Bluetooth headphones, but television speakers remain aligned. Adding an audio-delay setting would worsen the headphone case. The comparison points toward delay in the wireless output route and helps avoid changing a global offset that would damage the already-correct speaker path.
Practical actions
- Identify whether sound leads or follows the picture.
- Compare internal speakers with the problematic output route.
- Check the same timing cue early and late in playback.