Introduction to Wi-Fi radios

BBC iPlayer on-demand radio programmes now at higher quality than DAB

All of the BBC's on-demand radio programmes available via the iPlayer are now at higher audio quality than on DAB.

The BBC has been in the process of switching its stations' Internet streams over to using its new 'Coyopa' encoder/servers over the last couple of weeks, and the last station due to make the switch was Radio 3, so I spent some time listening to various Radio 3 programmes on the iPlayer on Sunday, and they all sounded far better than Radio 3 programmes on the iPlayer had done previously, and I've since had it confirmed by James Cridland, who's in charge of the BBC's Internet radio streams, that Radio 3 has switched over to using the Coyopa encoders. So now that all of the BBC's on-demand programmes are being encoded using the Coyopa encoder/servers, this means that all of the iPlayer on-demand streams are now at higher quality than on DAB.

Higher quality than DAB

The iPlayer on-demand radio streams started using MP3 back in July, and the bit rates of the iPlayer streams are all using the same or higher than are used on the same stations on DAB. So because MP3 is far better than the MP2 audio codec that's used on DAB, the audio quality has potentially been better than on DAB since July.

However, until now the audio for all of the BBC's Internet radio streams has been 'transcoded', which in the case of the BBC's Internet streams meant that the audio was first decoded from MP2 followed by being encoded to MP3. Transcoding degrades the audio quality, and this has been why the audio quality of the iPlayer on-demand radio streams hasn't been very good up to now despite their potential.

The new Coyopa encoder/servers, which are located in Broadcasting House in London, are being fed with uncompressed audio directly from the studios, so the audio is no longer being transcoded, and this is what has led to the quality of the on-demand streams overtaking DAB.

Another quality improvement over DAB, although this has been true since July, is that Radio 7 and the Asian Network, which are permanently broadcast in mono on DAB, do have stereo on-demand streams.

iPlayer on-demand streams vs DAB

The table below shows the bit rates, audio mode (i.e. stereo/mono) and audio codec used for the iPlayer on-demand streams and BBC DAB stations:

1 - Radio 3's bit rate is reduced to 160 kbps when R5 Sports Extra is on-air before 5pm, and Radio 4 is reduced to 80 kbps mono when Radio 5 Sports Extra is on-air after 5pm

The switch to AAC/AAC+ will hopefully improve quality further

Both the live and the on-demand radio streams are going to switch over to using AAC/AAC+ over the next few weeks (possibly in time for Xmas), so although the BBC originally said that they were going to use lower bit rates for AAC/AAC+ compared to what they're using with MP3 (because AAC/AAC+ is a more efficient codec, so the same quality can be achieved at a slightly lower bit rate than with MP3), I'm hoping that they'll maintain the same bit rate levels they're using now, in which case the quality would improve further.

Internet bandwidth costs for content producers such as the BBC fall in-line with Moore's Law, i.e. the cost halves every 18 months. So the cost of Internet bandwidth for the BBC has actually fallen by over 30% in the 10 months since they first announced in February that they were going to improve the quality of the Internet streams later this year, and the BBC would show itself to be a serious Christmas Scrooge if it did actually reduce the bit rate levels of the on-demand streams when they switch to AAC/AAC+.

World Service

Some of you may have spotted that the World Service isn't included in the above table, which is unfortunately because I've read that the World Service isn't going to improve in quality like the other BBC stations. The person that said this was the person in charge of new media for the World Service, and he said it was due to some arcane rule or other that meant that UK listeners aren't allowed to receive higher quality than overseas listeners get. However, the only country where the World Service is available on DAB is the UK, so how does he justify providing the World Service on DAB in the UK when they don't provide it on DAB in any other country? Sounds like BBC double standards again to me.

He did go on to say that he's looking into using new audio formats, which probably means that he's looking into using AAC+, because AAC+ is the ideal codec to use for the kind of very low bit rate -- e.g. 32 kbps -- Internet streams that the World Service uses.

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