[This post is re-produced from my post on the all new BBC R&D Blog]
I’m Rowan de Pomerai, a technologist at BBC Research & Development. I’ve recently returned to London having spent around 7 months in our northern lab in Manchester. As Anthony mentioned in his post, the last year has seen BBC R&D’s presence in Manchester grow from a handful of engineers to staff numbers in the double digits, with plans to keep that number rising as more staff move north in advance of the move to MediaCity:UK. Where the first few early movers got by with a small office space and a basic broadband-type connection to the R&D network in the south, that situation was rapidly becoming untenable. Physically we were bursting at the seams, and the lack of facilities was restricting the work we could do to certain types of software development and little else. We needed more space and more facilities if we were to grow a lab which could match the breadth of output provided by the London base.
Well, today is my last official day working on BBC HD audio. Somehow I don’t think this project will leave me alone just yet, but after a week’s leave, my main focus will be elsewhere. So I thought I’d take the opportunity to talk about something which has consumed a fair bit of my time, but which I haven’t blogged much about: metadata. For the uninitiated, metadata is “data about data”. A photo’s metadata for example might tell you what camera it was taken with, where it was taken, what exposure was used and so on. In the case of BBC HD’s audio, metadata is carried by the Dolby E and Dolby Digital streams we use, and has two main functions: it describes the audio being carried, and it controls the decoders in your homes. One parameter, often called dialnorm (for Dialogue Normalisation), tells your decoder how loud the programme is, so that it can attempt to smoothe out differences between programmes and channels to give you a more consistent loudness. Another set of parameters control what happens when your decoder downmixes the audio, meaning when it produces a stereo mix for your stereo speakers from the surround sound we may be sending. It’s important stuff, so we have to make sure that metadata survives our distribution chain, and sometimes we even have to add metadata to a programme automatically, which can be tricky. Here’s some of the work we’ve done…
