jonathan.rawle.org

DAB Digital radio in the UK has long suffered from sound quality issues on many stations due to broadcasters’ preference for squeezing a large number of stations into their multiplexes. The low bitrates utilised mean most stations are even broadcast in mono: a huge backwards step from FM.

It is often suggested that anyone wanting higher quality radio broadcasts should listen to the radio channels provided on Freeview, the UK’s digital TV platform. For BBC radio stations, this still holds true. These are generally broadcast at 128 kb/s on DAB, but 160 kb/s on Freeview. Some stations such as Radio 4 Extra and the Asian Network are even bumped up from mono to stereo on Freeview. The only exception is Radio 3, which on DAB is 192 kb/s and full stereo, rather than joint stereo, at times when there isn’t an extra channel for the Daily Service, or live parliamentary or sports coverage.

However, Freeview has long been lacking many commercial radio stations, most notably the UK’s most popular national commercial station, and the only one broadcast on FM: Classic FM. Therefore, I was pleasantly surprised this week to hear an advert for Classic FM on Freeview. My surprise turned to dismay when I looked at the technical details. On Freeview, Classic FM is only broadcast in 64 kb/s mono. Now, on DAB, Classic FM is one of the most generously-treated stations, in 128 kb/s joint stereo. It’s always worth remembering that DAB and Freeview both use the MP2 audio codec, which is approximately two-thirds as efficient as MP3. The Classic FM DAB bitrate has been slowly eroded over the years, but 128 kb/s is just about acceptable. I would have hoped Classic FM on Freeview would have been at least 160 kb/s like the BBC stations.

I have to wonder what Classic FM’s owners, Global Radio, hope to achieve by putting such a poor version of the channel on Freeview. Presumably, they are hoping to pick up new listeners who would not tune in on an FM or DAB radio. Let’s hope the tinny, monophonic sound doesn’t put them off. My fear is that Global will later declare their move to Freeview a success, and use it to support claims that a low bitrate mono is perfectly acceptable for the station on DAB too, allowing them to squeeze an additional advert-packed station into the multiplex, and leaving Classic FM listeners with the same tinny, mono sound full of digital artefacts that fans of Smooth Extra and Planet Rock have to put up with.

There are, thankfully, still ways to listen to high quality digital broadcasts at home, although neither is really practical for listening on the move. One is via the digital satellite platform, which is free once you have a dish. On digital satellite, Classic FM is broadcast at 192 kb/s. The other way is to listen via the internet. Classic FM is available as 128 kb/s MP3 online, and stations such as Planet Rock are actually in stereo. In fact, most stations are available in higher quality online than via any type of over the air broadcast, the most extreme example being BBC Radio 3, which streams at 320 kb/s in AAC format.

The advice for anyone serious about music is to invest in a receiver that allows you to listen to internet radio – or at least in a cable to run from your PC to your hifi. This will also give you access to thousands of radio stations from around the world, including online-only stations free of interruptions or adverts. You may just find you prefer a station that doesn’t tell you every half an hour that you could be listening to a far inferior quality broadcast via your TV.

Useful links

• DIGITALBITRATE – details of the bitrates of digital TV broadcasts across Europe
• DAB Ensembles Worldwide – details of DAB digital radio multiplexes around the world