sorry to ask a slightly OT...
is there a good guide to bitrates/sound quality to UK radio.
Satellite >= DVT > DAB, but where is FM?
Also is there a list of bitrates anywhere for the TV sources?
is there a good guide to bitrates/sound quality to UK radio.
Satellite >= DVT > DAB, but where is FM?
You'll find something -- including UK-specifics -- at http://heim.ifi.uio.no/~sverre/papers/07_A...B-Corrected.pdf (http://heim.ifi.uio.no/~sverre/papers/07_AES-DAB-Corrected.pdf) , presented at AES 31st International Conference, London, UK, 2007 June 25–27.
FM radio is an analog broadcast, so it doesn't have a bit rate and there's no single number to compare it with the digital broadcasts. With FM the main thing affecting quality is simply how good of a signal you pick up - is the signal strong enough, is there any interference, etc. Hissing and dropouts are symptoms of poor reception.
With digital broadcasts, you can't pick up a "fuzzy" signal, you either get the bits successfully or you don't. So, once you've picked up a digital broadcast, the quality's going to be determined by the digital parameters like which codec and bit rate is being used. Unfortunately I've got no idea what they use for the digital broadcasts.
With FM the main thing affecting quality is simply how good of a signal you pick up - is the signal strong enough, is there any interference, etc. Hissing and dropouts are symptoms of poor reception.
There are factors in the receiver that determine sound quality as well such as the stability of the local oscillator, performance of the quadrature detector, filters, amplifiers, etc.; but you're right it isn't as cut and dry as digital broadcast.
With digital broadcasts, you can't pick up a "fuzzy" signal, you either get the bits successfully or you don't. So, once you've picked up a digital broadcast, the quality's going to be determined by the digital parameters like which codec and bit rate is being used. Unfortunately I've got no idea what they use for the digital broadcasts.
There is a thing called "soft degradation" where digital transmission is designed such that the quality received will be gradually degraded (analog to how FM radio degrades) when the signal quality is degraded.
But you are right in that the simple implementation of text-book digital designs, you will typically either have sound, or none. After the initial losses incured by the lossy encoder, that is.
-k
@Porcus
thank you for that informative paper
http://www.audiomisc.co.uk/BBC/iPlayerRulesOK/Page1.html (http://www.audiomisc.co.uk/BBC/iPlayerRulesOK/Page1.html)
http://www.audiomisc.co.uk/BBC/Proms2011/i...RulesAgain.html (http://www.audiomisc.co.uk/BBC/Proms2011/iPlayerRulesAgain.html)
Other than Radio 3, I find the dynamic range compression to be the quality killer on most broadcasts.
128kbps AAC on iPlayer for all BBC national stations is fine.
192kbps MPEG-1 layer II for the main BBC national stations on DSat and DTT is OK (for a long time in the mid-2000s, DSat was a far better feed than DTT even though the bitrates were the same - I no longer have DTT to compare)
DAB is for portable mono radios.
For BBC nationals, FM depends entirely on reception, has equal or more DRC on all networks, is always NICAM fed, but avoids AAC/mp2. Some people claim it sounds better, but I think that's down to the extra DRC and noise.
Cheers,
David.
who IS that guy.
None of this short, bulletised style of writing, they are long articles about the subject.
However it would be good to know why R3 and BBC1 have different views on how the music at the proms should sound.
That guy is Jim Lesurf. As well as his home page...
http://www.audiomisc.co.uk/index.html (http://www.audiomisc.co.uk/index.html)
...you can find plenty of his posts on Usenet in uk.tech.broadcast (just search for his name).
Cheers,
David.