It seems that the BBC is due to launch “HD” audio streaming for its online radio broadcasting, starting with their Radio 3 service in December 2010. They’ll also be running a trial of the technology for this year’s Radio 2 Electric Proms on 28th to 30th October 2010.

Currently we’re used to listening to many BBC national and local stations on iPlayer, most (perhaps all) of which use 128Kbps AAC encoding in stereo. These streams have not been running in their current form for all that long, and brought significant improvements over the previous up-to-56Kbps RealPlayer streams both in terms of quality and accessibility, making hi-fi playback of online radio streams pleasurable for the first time, and certainly a big improvement over the audio quality DAB currently offers.

Initially the new “HD” stream will only be avalailable for Radio 3, and will use 320Kbps AAC-LC stereo encoding. Experts with more knowledge than I can explain what the difference means from a technical perspective, and therefore why it is seen as such an improvement. I’ve not yet listened to any of the trials that were arranged for this years Proms, but in my work I find myself playing with many different audio and video compression systems for online distribution and I have to say that there is a significant difference between 128Kbps and 320Kbps AAC audio. The former is “good enough” for many, but the latter is so close to either “lossless” or “PCM” in various forms that many won’t be able to tell the difference between compressed and uncompressed sources.

This is a huge step in the right direction – digital audio broadcasting in the UK has long suffered demonstrable quality issues that are easily audible even on small DAB receivers and laptops, so anything that kills these audio data compression artefacts is a very good thing. Despite the lower-quality MPEG encoding currently used by DAB, I’d love to see them lose some of the fringe stations and put the extra bandwidth to better use on the national stations.

Certainly I’ll be very interested to hear the new HD streaming during the Electric Proms – and will report back here with my findings.

Links here:

BBC Radio Blog entry

BBC Radio 3 Blog entry

BBC Radio 2 Electric Proms (no mention on here yet of HD trials)