BBC Research and Development have published an interesting white paper on their website detailing the challenges in keeping Dolby E (a compressed standard for distributing surround sound around broadcast areas) in sync and free of artefacts, preserving Metadata etc.

http://www.bbc.co.uk/rd/pubs/whp/whp175.shtml

The BBC run a single HD network, broadcast directly from London, with no local stations in the way - but the issues about 2.0/5.1 switching etc., avoiding splats etc. are interesting.

(Apologies for previously posting in the wrong forum)

Thanks for posting this. Fascinating stuff. I only wish I could understand all of it. But it's good to see so much attention is being given to sync issues, which seem to have reached almost epidemic proportions.

I wish there were some way to broadcast the BBC's sync test (or its equivalent) here in the US, but almost everyone is on the air/cable 24/7. I also appreciate the clear explanation of why having video precede audio is less objectionable than the reverse, although even a one frame error is noticeable.