New DAB Standard
Discussion
Looks like ALL current DAB radio units will be made obselete. The WORLD DAB standards look like enbracing AAC and MPEG-4 dropping MPEG-2. ALL current UK DAB units ONLY have MPEG-2. A legacy of that Chip designed by the owners of the UK's DAB spectrum in their desperate attempt to get a consumer DAB reciever on the shelves. It's not all bad news through. The original DVB recievers will be obselete soon too. The compression used will be changed and the original OnDigital units cannot be altered/updated. However from the original 1 million units there are less than 250,000 still in use so by the time the change is made there won't be many left in use! The same will apply to the existing DAB units when the new compression algorythms replace MPEG-2.
HI-FI World March issue. Steven Green's column on page 79. The standard is the "Eureka 147 DAB". It includes a Statement from OFCOM. The New Standard will allow all current stations to be carried as well as all the remaining stations but still have a signal quality very close to CD whereas the current standard is below that of MP3.
CD has a bit rate of 256Kbps the best DAB can manage is 192Kpbs which is the rate most MP3's are ripped at. Most DAB stations are now down at 128kBPS which is rated as "annoying" when blind tested. See this site for more info on the current situation.
DAB
>> Edited by telecat on Tuesday 7th February 01:42
DAB
>> Edited by telecat on Tuesday 7th February 01:42
sadako said:
Considering the signal quality of MP3 is slightly below that of CD (very slight compression loss) that statement is not much of a comparison. What does annoy me is that i'd have to find a way to upagrade my car stereo
Its actually well below uncompressed CD, in fact on a decent system its unlistenable.
Yep. "Decent system" is the key word. The distortion introduced by MP3 is very similar in some ways to that introduced by the usual crappy speakers, so people with crappy systems (the vast majority) don't notice it and its use spreads like a cancer to the detriment of people who actually care about what their music sounds like enough to get a decent system. This pisses me off.
Most of DAB's problems is that it uses MP2 - audio level two of MPEG-2, not the superior, but more 'difficult' mp3. Welcome to 1990 or so...
Couple that with limited paltry bandwidth and you get godawfull sound quality that in a lot of cases sucks compared to FM.
Oh and DAB is the worst way to listen to digital radio, sky/freeview/cable etc are all better (higher bitrate/better codecs etc).
Qell I wont get over excited at this announcment, the signal wont reach NZ anyhow..
Couple that with limited paltry bandwidth and you get godawfull sound quality that in a lot of cases sucks compared to FM.
Oh and DAB is the worst way to listen to digital radio, sky/freeview/cable etc are all better (higher bitrate/better codecs etc).
Qell I wont get over excited at this announcment, the signal wont reach NZ anyhow..
CD has a rate well above 256kbit. An uncompressed CD data stream is 2*16*44100 = 1.411Mbit. Lossless compression with APE or similar gives a ratio of 0.4 to 0.6, so that's approximately 700kbit information rate.
I am still far from convinced about DAB. The modulation method has made decoding expensive in terms of cpu (or fpga) power and manufacturers are still struggling to get it cheap enough. Performance on a small antenna is absolutely hideous. It was inevitable that they would push the bit rate down as low as they thought they could get away with and any successor to DAB may well do exactly the same. Does anyone have experience with mobile satellite radio in the US? That may be one way forward.
I am still far from convinced about DAB. The modulation method has made decoding expensive in terms of cpu (or fpga) power and manufacturers are still struggling to get it cheap enough. Performance on a small antenna is absolutely hideous. It was inevitable that they would push the bit rate down as low as they thought they could get away with and any successor to DAB may well do exactly the same. Does anyone have experience with mobile satellite radio in the US? That may be one way forward.
Zad said:
It was inevitable that they would push the bit rate down as low as they thought they could get away with and any successor to DAB may well do exactly the same. Does anyone have experience with mobile satellite radio in the US? That may be one way forward.
Satellite radio will probably not happen in Europe simply because the cost of launching the satellites is huge and we don't speak the same language. I have used the system a lot and it is good, unfortunatly for some it is good for the same reason DAB is popular in the UK, listener choice rather than absolute audio quality.
Whoever claimed DAB could only support 192kbps is not quite right, the Canadian implimentation of DAB uses 256kbps minimum for music channels, this sounds really rather good. The limiting factor on bit rates is the BBC and commercial operators squeezing too many channels into each multiplex.
BTW Steve Green is quite well known in DAB circles as an anti DAB protagonist and makes many good points, however they are usually spun so much even Alistair Campbell would look on in awe. For instance the UK broadcasters are not obliged to switch to any new worlddab standard just because it exists so don't worry about your radios becoming obsolete just yet.
Cheers
Ben
edited to correct typo
>> Edited by benyeats on Tuesday 7th February 11:39
I listen to dab radio all day long on a pair of fairly decent headphones and the quality is fine. 6 music gets encoded at 128Kbps but it sounds like it's much better than that (compared to encoding at 128Kbps at home). I encode at 320Kbps normally and it doesn't sound quite as good as that but it's perfectly listenable. I believe that the kind of people who would spend thousands on a system and really just sit down and listen to music would have a point but for the rest of us who are just listening to music while we do other things are just blowing hot air when they moan about the quality. Sure it could be better but it's perfectly fine as it is.
The main benefit to me is that it works around computer monitors which fm radios don't.
Mark
The main benefit to me is that it works around computer monitors which fm radios don't.
Mark
One of the biggest issues with DAB is the quality of the audio generated at the radio station.
A CD could go through at least 6 encode/decode systems BEFORE it comes out your radio.
For example.
(stage 1)Music track made at a recording studio dubbed onto CD.
(stage 2)This is sent to a distrubution company, Recorded into their system and sent to radio stations.
(stage 3)radio stations Dub the audio onto the playout system (playout systems usually MP2 file format). Must point out that a lot of radio groups are installing new playout systems that play linier files)
(stage 4) When audio gets played from the playout system through the studios
Stage 5 the audio will then hit a digital audio processor (fancy graphic EQ and compressor) then onto the encoders that transfere the audio to the transmitter, (stage 6)you then decode the audio again so you can hear it.
thats why DAB sounds crap.
Until we can eliminate all the encode /decode processes DAB will always sound poor
PS
I am a broadcast engineer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A CD could go through at least 6 encode/decode systems BEFORE it comes out your radio.
For example.
(stage 1)Music track made at a recording studio dubbed onto CD.
(stage 2)This is sent to a distrubution company, Recorded into their system and sent to radio stations.
(stage 3)radio stations Dub the audio onto the playout system (playout systems usually MP2 file format). Must point out that a lot of radio groups are installing new playout systems that play linier files)
(stage 4) When audio gets played from the playout system through the studios
Stage 5 the audio will then hit a digital audio processor (fancy graphic EQ and compressor) then onto the encoders that transfere the audio to the transmitter, (stage 6)you then decode the audio again so you can hear it.
thats why DAB sounds crap.
Until we can eliminate all the encode /decode processes DAB will always sound poor
PS
I am a broadcast engineer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
david87M3 said:
One of the biggest issues with DAB is the quality of the audio generated at the radio station.
A CD could go through at least 6 encode/decode systems BEFORE it comes out your radio.
For example.
(stage 1)Music track made at a recording studio dubbed onto CD.
(stage 2)This is sent to a distrubution company, Recorded into their system and sent to radio stations.
(stage 3)radio stations Dub the audio onto the playout system (playout systems usually MP2 file format). Must point out that a lot of radio groups are installing new playout systems that play linier files)
(stage 4) When audio gets played from the playout system through the studios
Stage 5 the audio will then hit a digital audio processor (fancy graphic EQ and compressor) then onto the encoders that transfere the audio to the transmitter, (stage 6)you then decode the audio again so you can hear it.
thats why DAB sounds crap.
Until we can eliminate all the encode /decode processes DAB will always sound poor
PS
I am a broadcast engineer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Its a good point, Optimod and all, but the fact remains that DAB bandwidth is severely limited, and still rubbish. FM transmissions (Radio 4 in particular) still sound excellent, using the same digital links you mentioned.
RobM77 said:
DAB Is nowhere hear as bad as FM though! FM just sounds completely rubbish! All 'thin' with no frequency range. Well, at least it does in my car (I don't have a radio at home to compare with).
You'll find that isn't the technology, but the prevalence of compression of the dynamic range to make the signal appear 'louder' to somebody casually scanning the airwaves, and to make it more audible in a busy environment.
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