Who listens to DAB?

Trick of the Tail

Strictly speaking, FM isn't like CD quality because the upper frequency limit is 15kHz and the audio is pre-emphasised. Add to that the audio processing that FM stations use, some good, some not-so, and you get a quality NOT comparable to CD quality.

DAB does indeed use lossy codecs to bit-rate compress the audio, but if sone well and not too much - and if it's DAB+ which uses AAC coding, the quality can be very nice.

Upper frequencies are not limited to 15kHz (usually 20) and there's no pre-emphasis.

Badly-done DAB sounds bad, nicely-done DAB sounds good. Same badly done FM/nicely done FM!

I'm listening to Nova, Beat and Zenith on DAB a lot lately, all sound at least as nice as FM.

L1011

Mr Williams wrote: »

DAB by its very nature is a "lossy" audio format which means data is thrown away to compress the sound. FM is not compressed its comparable to CD quailty. Also the fact that its analogue means you got a much more natural sound, digital audio can sound very artificial.

I'm (very) aware how DAB and FM work. DAB done properly has no inherent sound problems, despite the incredible FUD about it.

In a huge amount of cases the audio being played out isn't at the capabilities of DAB to begin with - pretty much any voice clip, ISDN interview or LAN playout music (which is basically everything these days) will be below what properly configured DAB can offer anyway.

Antenna

Trick of the Tail wrote: »

Strictly speaking, FM isn't like CD quality because the upper frequency limit is 15kHz

But very few people can actually hear 15kHz and above.

I can hear the 15.625 kHz line whistle from a CRT TV set, but I have asked several others and they can't.

Surely DAB stations (or any other digital broadcast audio with lossy compression) aren't generally transmitting audio above 15kHz (even if its technically possible)? - doing so (for a given bitrate) would mean 'less representation' of the lower audio frequencies which people do actually hear and take notice of.

Can anyone list examples of the upper audio frequency limits in use on various DAB services here (and/or in the UK)?

L1011

Generally 24kHz (48kHz MP2, joint stereo).

Fuzzy Clam

MYOB wrote: »

Generally 24kHz (48kHz MP2, joint stereo).

Audio frequency

Fuzzy Clam

MYOB wrote: »

Generally 24kHz (48kHz MP2, joint stereo).

Audio frequency

vinnielo

Back in 2009, I did a few tests of London.
Gonna have to link to another forum, if that's OK.

http://forums.digitalspy.co.uk/showthread.php?t=1157076
Ranging between 12kHz and 15kHz for stereo stations and 8kHz and 11.5kHz for mono stations.

L1011

Fuzzy Clam wrote: »

Audio frequency

???

24kHz is the audio frequency upper limit, as the codec doesn't support any more.

Unless they're operating at 24kHz in which case its 12kHz; there are no other limits.

In general most music content on any radio station is going to be 44.1kHz CD captures which can only give about 20kHz due to transition bands in the codec. And in most cases, it's stored using lossy compression anyway.

Trick of the Tail

Indeed, the Nyquist frequency is a little less than half the sample rate.

But the point was made that DAB isn't as good quality as FM. My point was that it can be better - depending on the bitrate used for the stream and the coding technique; and depending on how 'good' the FM is you're comparing it to.

However, the salient issue is that when we're talking about relatively subjective quality differences, the public don't care. But what they do care about is the programming.

I utterly disagree with the assertion that DAB is a viable replacement for FM. That should not happen. But DAB is a good increment to the FM band; managed and regulated properly (i.e. light touch regulation), DAB could become an excellent medium for more specialist output stations.

Leave the big boys on FM, to do what they do best. Licence DAB properly NOW, such than a myriad of smaller organisations can produce diverse content on DAB - available there for anyone who wants to take the trouble to listen.