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.