The Scourge Of SCART
I thought it was time to give you a quick update on some of the technical issues that have come up around BBC High Definition over the last couple of months and what has been happening since the Olympics.
We have taken some time to look at a lot of the issues bought up by you and a few of the things I wanted to investigate myself.
The big issue of 5.1 / 2.0 switching. Thanks to everyone commenting on this blog and elsewhere to give feedback while we were trying switching options. It's now working, but not as well as we would like - for example, we still have more work to do before we can move between stereo and surround programmes without having to put silence between them.
When things are changed, then no matter how well you plan there's always something that tries to catch you out. While we where upgrading some of the Dolby equipment, we came across an "interesting" problem - fortunately, it didn't go to air!
Some of you may know that we use Dolby E to move surround sound and metadata through the playout area (and if you read my post about the Eurovision Song Contest, you will know how important the metadata are!).
Dolby E is a frame-based data stream - in other words, it comes in packets timed to the video signal. If any packet is corrupt or mistimed, the whole frame is invalid. Some devices can deal with this, but others don't recognise the corrupted package for what it is and think it's a chunk of PCM audio. A Dolby E packet contains a lot of data and if any device treats it as digital audio, it comes out as a very loud "splat". Fortunately for your ears, it's only around 40ms long - this is, however, somewhat unfortunate for your speakers!
The work to get surround and stereo to work together is still going on and I will update whenever we have more to report.
Danielle talked about some of the quality issues you reported on Friday Night With Jonathan Ross in her What Works Best? post. We have looked at the whole studio, post-production and transmission chain to see what was causing the problems.
There were a couple of processes that made some of the cameras quite noisy: these have now been addressed and last Friday's show (October 3rd) looked a lot better, but we are still trying to find ways to improve the quality across all programmes.
Picture quality issues bring me to another story. I'm sure you are getting used these stories from my previous posting about the thoughts of my daughter - who, by the way, is now officially a stroppy teenager!
Actually, this is about a trip to pick her up from one of her school friends' and getting invited in for a coffee while I waited. "You work for the BBC" was the opening from the other dad - "do you have anything to do with this high definition stuff?". My answer was a bit muted, thinking, "what's next?"! He then said he didn't see what all the hype was about: the pictures were a bit better but nothing to get excited about.
I asked the usual questions about type of TV and how he received HD. As expected, it was a new 50" plasma - quite a nice one actually, and a Sky HD box with the full subscription package. "Come and have a look" - so, shoes off, coffee mug in hand, we go through.
He turned the telly on and, after wincing from the volume of one of the music channels left on by his daughter, we went to the BBC HD channel, which looks - to put it politely - "crap".
At this point I had to put down the coffee mug and admit to my job title. The diagnosis took about five seconds - so, trying to look very professional, I reached round the back of the TV and pulled out the SCART lead. After the usual bumps and flashes, the pictures re-established themselves looking like the high definition I would expect.
There was a short "Ah!" and we went back to coffee and chat about the length of time two teenage girls can spend on a phone after they've only just been at school with each other!
This was not the first instant repair I've done and I doubt it will be the last. One of the things I'm always doing is taking TVs out of "Vivid" or "Dynamic" or some other mode that makes the screen hot enough to do toast on. Others changes include setting the contrast and brightness levels to something resembling normal and most important, turning the sharpness down to zero and finally setting all the picture enhancing modes to "off". That usually results in reasonable pictures on any telly and tends to make HD look like HD!
I'm not sure what to do about the SCART lead. It seems to be the biggest single quality filter in the chain, especially as the default setting for the SCART output on many set-top boxes is PAL. My recommendation is not to have them at all, but there are still a lot of devices out there that seem to need them.
Over the next few weeks, we are looking at some new cameras and field recorders: we will keep looking at picture quality issues as they come up and talking to Dolby about a better way to mix 5.1 and 2.0 programmes - please keep letting me know how it sounds at home. I have a Sony AV system, but I need feedback from as many systems as possible.
Also, if you know anyone with a SCART lead connected to their HD set-top box, either pull it out or make sure that the SCART switching menu option is set to "OFF"!
Andy Quested is Principal Technologist, BBC Future Media & Technology.