Fixing audio that is out of sync with the picture

Sound and picture arriving at different times is one of the most distracting faults in home viewing, and one of the most fixable. It is almost never a cable or a broken device. It is processing: two signals that left together, took different routes, and had different amounts of work done to them.

Establish which one is late

This single observation determines everything that follows, and it is worth being certain about before changing any setting.

Dialogue with a clear consonant is the easiest test. Applause and percussion also work well because the attack is sharp.

Where the delay comes from

Picture processing

A modern television does a great deal to an image before displaying it: noise reduction, upscaling, HDR tone mapping and motion interpolation. Each stage takes time, and interpolation is the most expensive because it must hold several frames to work between them.

This is why switching a television into its game or low-latency mode frequently resolves a sync problem outright — that mode exists to strip out exactly this processing, and audio delay is fixed as a side effect.

Audio processing

A soundbar or receiver decodes the incoming format and may apply room correction, bass management and virtual surround. Object-based formats require substantially more computation than channel-based ones, because the position of each sound object must be resolved before anything can be rendered.

A useful diagnostic follows from this: if sync is fine on ordinary stereo content and wrong on object-based audio, the soundbar's decoding is the source, not the television.

The connection

How audio leaves the set also matters. Routing through the television adds its processing to the audio path; connecting a source directly to an amplifier avoids it entirely.

Fixing it, in order

1. Turn off motion smoothing. The largest single source of video delay, and turning it off improves film reproduction anyway.
2. Try the television's game or low-latency picture mode. If this fixes it, picture processing was the cause and you can decide which processing you actually want.
3. Use the delay control. Almost every television, soundbar and receiver has one, usually called audio delay, lip sync or A/V sync. Adjust in small steps against dialogue. If audio is late, this control usually cannot help — it delays audio further; delay the video instead if the television offers it.
4. Simplify the chain. Connect the source straight to the television, or straight to the soundbar. If sync corrects, the removed device was adding the delay.
5. Check whether it is only one app. If so, it is the app's own audio pipeline, and no amount of hardware adjustment will fix it properly.

When it is not your equipment

Some sync errors are in the content or the service. Two signs point that way: the problem appears on one title only and follows it across devices, or it drifts progressively during a live stream rather than staying at a constant offset.

Progressive drift on live content in particular is a broadcast or encoding fault at source. No local setting corrects it, and it is worth reporting to the service rather than adjusting around.

More practical coverage is in the Guides hub. Terms are defined in the glossary.