Watch the DVD of Grosse Pointe Blank. Notice how the audio track drifts lazily out of sync with the video. It happens with a lot of streamed films and TV episodes too. Frustrated? Yeah, me too.
The Television Audio Synchroniser would examine visual cues such as mouth movements (using facial recognition), gunshots and so on and match them to the audio, moving the audio ahead or behind to synch it back up with the image.
As the device (either integrated or set-top box) would have to change the audio lead/lag for every scene it would have to read-ahead for half a minute or so and adjust ahead of time while ensuring a smooth audio transition from one scene to the next.-- st3f, Dec 03 2016random, halfbakery