radio signatures

There's been a small amount of fuss in the UK about the opening theme for BBC Radio 4, played every day at 0530GMT - it's going to be cancelled and replaced by some news. So it seems appropriate to post about some work I've been doing at BBC Radio & Music on the subject of audio signatures for radio.

I've been playing around with the iTunes Signature Maker (written about previously here) which takes your favourite iTunes songs and then mixes them into an n-second compilation of your collection. I've modified the code to run over some of BBC Radio. I have, in fact, made it much less clever than it was originally - now it just grabs a random chunk from each MP3 file in a directory, currently it uses 5 seconds per hour of the original. I have a directory for each radio station on a particular day with an MP3 file for each programme and I run the application over this. Each random chunk is then cross-faded into the next one in the same order as the programmes were broadcast. This gives a 1-minute signature file per day per radio station, hopefully representing what went on that day...

• Radio 1 (mainstream music) on 04/01/06
• 1Xtra (black music) on 12/01/06
• Radio 2 (popular music) on 12/01/06
• Radio 3 (classical music) on 12/01/06
• Radio 4 (speech) on 04/01/06
• FiveLive (news and sport) on 12/01/06

Some things that you can hear from these...how Radio 1, Radio 2 and 1Xtra play more specialist music (e.g. asian, UK garage, hard rock, country, blues etc.) late at night, i.e. the beginning and end of the samples. On Radio 4 you can hear a snatch of the shipping forecast and something about charles kennedy. And because Radio 4 programmes tend to be 30 minutes to an hour long there are more, shorter snippets which I think gives an impression of the diversity of the content. And on Radio 2 you can hear its mixture of chat and music.

They don't sound brilliant, certainly not as good as a hand-crafted ident, and there are some very jarring changes from music to speech and vice-versa. I also found the mixing between different classical pieces in different keys quite nasty. The main advantage of this seems to me to be the fact that it is an automated process so we can generate these signatures easily for all the BBC's radio networks or programmes. Obviously expert radio producers can generate much better representation and mix of a radio station's sound but this is a highly skilled and lengthy process.

So, what is it for? I don't quite know yet. Maybe for generating automatic idents or jingles to represent a radio station - ones that are always up to date. Or for taking snapshots of a station in time - capturing the zeitgeist in news or music; maybe you could browse back in time and listen to a snapshot of radio from 10 years ago. Or to assist in browsing and navigating audio - a quick, representative burst of a station that plays when you rollover the logo on the website or a version of the BBC Radio Player where you can get a preview clip of a station, genre or programme to help you decide whether to listen. And there are potential applications in accessibility for music and radio - not just for people who may have physical or visual limitations but for all of us who face the "social model" of disability - how do you use a visual interface while driving or when your iPod is in your pocket and it's a cold day and you're wearing gloves?

I'd like to make it a bit cleverer so it grabs representative chunks rather than random chunks but, to be honest, I'm not sure you'll be able to tell the difference. Though it would be worth avoiding the top of the hour when lots of the stations play news bulletins. I'm also thinking about visual representations of audio, like this and this, and how these signatures could also be visualised.