Introduction to Wi-Fi radios

Some BBC stations' listen again streams now at higher quality

This is a news article from 2008, and since this article was published the BBC has launched new high quality AAC streams for both the on-demand (listen again) streams and for the BBC's live Internet radio streams. The AAC streams are highest quality source of digital radio that the BBC makes available. An article about the new AAC Internet streams can be found here.

The listen again streams for Radio 1, Radio 2, 6 Music, 1Xtra and the Asian Network on the BBC iPlayer are now at higher quality as they're being delivered by the BBC's new 'Coyopa' servers.

Transcoding degrades the audio quality

For the last six years the BBC has been transcoding the audio for all of its Internet radio streams. Transcoding means decoding from one compressed audio format followed by encoding to a different audio format, and this degrades the audio quality.

In the BBC's case, it has been receiving the BBC radio stations off-air via satellite at Maidenhead (the same radio streams people on Sky can listen to), where the streaming servers are based. The audio is decoded from the MP2 format that the satellite radio streams are using, and the audio is then re-compressed to the formats that the BBC streams have been using.

So although the BBC's listen again radio streams on the BBC iPlayer have been using 128 kbps MP3 since July, they've sounded pretty dodgy, and worse than you'd expect 128 kbps MP3 to sound, which has been due to the audio being transcoded.

BBC's new Coyopa servers eliminate transcoding

The listen again streams for the stations mentioned above are now being delivered by the BBC's new Coyopa servers. These servers are based at Broadcasting House, and they're being fed with uncompressed audio streams directly from the BBC radio stations' studios, so the audio for these listen again streams is no longer being transcoded, and the quality is significantly better than it was.

The Coyopa servers will apparently start delivering the listen again streams for the other stations shortly as well.

Streams to switch to AAC/AAC+ over next few weeks

The BBC has also said that the Coyopa servers are now correctly generating AAC/AAC+ files for the listen again streams, and these should be launched within the next few weeks. The AAC/AAC+ streams will be rolled out on a station-by-station basis, and the AAC/AAC+ versions of the live streams will be launched at the same time as the listen again streams are launched.

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