"tony sayer" wrote in message
...
In article , David Looser
scribeth thus
"tony sayer" wrote in message
...

Well the number of the bits and the way you use them do affect the
quality of both Sound and Vision;!..
--

Indeed, but it's not necessarily the case that it's "more bits the
better".
Some recent digital cameras with high "megapixel counts" produce poorer
pictures than older ones with fewer megapixels.

Why do you think that is?..

Lens quality, imager quality, DSP algorithm quality......But whilst the
megapixel count is mentioned in characters a foot high in the ads, the lens
is hardly mentioned, and the other two not at all. Not surprisingly the
public tend to get the idea that megapixels is all that matters.


In digital audio systems a lot is dependent on the codec in use and MP 2
which is what DAB uses wasn't designed for use at 112K or so whereas
AAC was!..
--

Indeed. Back in the early '90s I was employed in professional comparative
listening tests of low bit rate (8 - 9.6kb/s) voice codecs. The differences
between them were marked, but that didn't necessarily make it easy to pick a
"best". One might produce the most natural speech when there were no errors
in the bit stream, whilst another might cope far better under high
error-rate conditions. It could also depend on voices, tests were carried
out with a variety of languages (using appropriate listening test panels) to
avoid "language bias". So yes, I do know a bit about listening tests and
codec dependency!

David.

"tony sayer" wrote in message
...

Its only in recent times that they have had an opportunity to downgrade
it owing to the bitrates they can set it at.. You'd never hear someone
from the pre digital times saying that they could -downgrade- the
transmission system in use.


Rubbish!. AM radio was downgraded by reducing it's bandwidth from 9kHz to
4.5kHz betwen the 1930s and the 1960s.


Oddly enough DAB was developed with the intention of making it all
better .. Reception and audio quality!..

Was it? evidence?

The problem is that what is good enough for the bulk of the audience may
not
satisfy the enthusiasts, how much cost do you impose on the system to
satisfy a small minority?

I wouldn't say it has to satisfy the enthusiasts as such but one would
have hoped for something as good as the existing system - or better
would have been used..

I am not persuaded that, taking all real-world factors into account, DAB is
not at least as good as FM.


In the particular case of DAB I think a small improvement is justified, as
it can be done at little extra cost. But even as things are now the notion
that DAB is clearly worse than FM is challenged by some serious
commentators.

Well cost = MUX bitspace so it isn't that simple and seeing that the UK
is going to be lumbered with the ancient system we have whereas other
countries are adopting better ones!..

It's important to adopt common standards with other countries. And now would
be a good time to do so.


David.

In article , Rob
scribeth thus
David Looser wrote:
"Rob" wrote in message
om...
Of course. In fairness the centre of the DAB 'whinge' was always that it
could have been so much better, and not that it was/is intrinsically bad.
'Better', as you seem to suggest below, can't always be detected even if
it has theoretical advantages.


Of course it could have been better, broadcasting quality is a compromise
between performance and cost, always has been. The broadcaster's aim is to
provide a quality that is "good enough" without being too expensive, both
for themselves and the buyers of receiving equipment.

The problem is that what is good enough for the bulk of the audience may not
satisfy the enthusiasts, how much cost do you impose on the system to
satisfy a small minority?


I don't know the costs of transmitting at higher quality. Presumably you
know they are prohibitive ...

Its the multiplex system where each MUX has so many bits .

Course the more bits the less services you can carry.

And bitz cost;!..

In the particular case of DAB I think a small improvement is justified, as
it can be done at little extra cost. But even as things are now the notion
that DAB is clearly worse than FM is challenged by some serious
commentators.


... and even if implemented, not worthwhile?

Debatable till the cows come home;!..



--
Tony Sayer

In article , David Looser
scribeth thus
"tony sayer" wrote in message
...

Its only in recent times that they have had an opportunity to downgrade
it owing to the bitrates they can set it at.. You'd never hear someone
from the pre digital times saying that they could -downgrade- the
transmission system in use.


Rubbish!. AM radio was downgraded by reducing it's bandwidth from 9kHz to
4.5kHz betwen the 1930s and the 1960s.


Humm .. I thought we were talking about radio that could be considered
as hi-fi ?..


Oddly enough DAB was developed with the intention of making it all
better .. Reception and audio quality!..

Was it? evidence?

Theirs plenty out there the ODFM modulation system is very good for
multipath and this is one of the reasons it was developed for..


The problem is that what is good enough for the bulk of the audience may
not
satisfy the enthusiasts, how much cost do you impose on the system to
satisfy a small minority?

I wouldn't say it has to satisfy the enthusiasts as such but one would
have hoped for something as good as the existing system - or better
would have been used..

I am not persuaded that, taking all real-world factors into account, DAB is
not at least as good as FM.

Well I don't know if you've ever listened to Radio 3 on DAB but it
always sounds not quite right rather metallic and thats much worse at
lower bit rates.. OK perhaps for portable use , apart from the power
consumption!, but for better listening don't think so.

Mind you sound quality is only one of the failings of DAB .. there are
others such as the MUX closed shop.

Some are wondering if we really -need- it;!...



In the particular case of DAB I think a small improvement is justified, as
it can be done at little extra cost. But even as things are now the notion
that DAB is clearly worse than FM is challenged by some serious
commentators.

Well cost = MUX bitspace so it isn't that simple and seeing that the UK
is going to be lumbered with the ancient system we have whereas other
countries are adopting better ones!..

It's important to adopt common standards with other countries. And now would
be a good time to do so.


Indeed but this it seems isn't happening especially in the mobile market
a common standard for digital Terrestrial radio would perhaps be a good
thing, but none's been decided on. Meanwhile most all new cars don't
have them fitted;!..

David.



--
Tony Sayer

Bancom Communications U.K. Tel+44 1223 566577 Fax+44 1223 566588

4 Wingate close, Cambridge, England, CB2 9HW E-Mail

In article , David Looser
scribeth thus
"tony sayer" wrote in message
...
In article , David Looser
scribeth thus
"tony sayer" wrote in message
...

Well the number of the bits and the way you use them do affect the
quality of both Sound and Vision;!..
--

Indeed, but it's not necessarily the case that it's "more bits the
better".
Some recent digital cameras with high "megapixel counts" produce poorer
pictures than older ones with fewer megapixels.

Why do you think that is?..

Lens quality, imager quality, DSP algorithm quality......But whilst the
megapixel count is mentioned in characters a foot high in the ads, the lens
is hardly mentioned, and the other two not at all. Not surprisingly the
public tend to get the idea that megapixels is all that matters.

Yes .. Oddly enough my 8 M/pixel produces worse pix than the old 3.5
one!..

And isn't that wonderful compared with the wife's ancient Canon..


In digital audio systems a lot is dependent on the codec in use and MP 2
which is what DAB uses wasn't designed for use at 112K or so whereas
AAC was!..
--

Indeed. Back in the early '90s I was employed in professional comparative
listening tests of low bit rate (8 - 9.6kb/s) voice codecs. The differences
between them were marked, but that didn't necessarily make it easy to pick a
"best". One might produce the most natural speech when there were no errors
in the bit stream, whilst another might cope far better under high
error-rate conditions. It could also depend on voices, tests were carried
out with a variety of languages (using appropriate listening test panels) to
avoid "language bias". So yes, I do know a bit about listening tests and
codec dependency!

You went involved in the MP2 codec tests for the development of DAB?..

David.



--
Tony Sayer

"tony sayer" wrote in message
...

You went involved in the MP2 codec tests for the development of DAB?..


No, voice codecs only, but the principle is the same. More to the point I
know just how hard it is, and the lengths we had to go to, to eliminate bias
from listening tests.

David.

In article , tony sayer
wrote:
In article , Dave Plowman (News)
scribeth thus
In article , tony sayer
wrote:
I don't supposed you've listened to that much net radio .. some
indeed is poor but some is very good...

The same applies to DAB - and FM.

To me the processing which is applied *in spades* to all the light
music stations is far more annoying than the low bit rates on DAB. I'd
rather not listen to badly set compressors pumping away.


Thats not a function of the transmission system just how broadcasters
use it!..

Perhaps that's the difference between us. I'm only interested in the sound
I hear in my room. I don't really care how it is unacceptably degraded.

--
*Forget the Joneses, I keep us up with the Simpsons.

Dave Plowman London SW
To e-mail, change noise into sound.

"tony sayer" wrote in message
...
In article , David Looser
scribeth thus
"tony sayer" wrote in message
...

Its only in recent times that they have had an opportunity to
downgrade
it owing to the bitrates they can set it at.. You'd never hear
someone
from the pre digital times saying that they could -downgrade- the
transmission system in use.


Rubbish!. AM radio was downgraded by reducing it's bandwidth from 9kHz
to
4.5kHz betwen the 1930s and the 1960s.


Could you qualify that please?
AM radio, AFAIK, has always has an audio frequency response limit of
4KHz which means it needs an RF bandwidth of 8KHz. The station spacing
is thus set at 9KHz to (theoretically) leave a guard band between
stations. In practice for most domestic radios this is of little
consequence as it would be nigh impossible to hear two stations on
adjacent frequencies - something that would be possible on a
commercial/professional receiver with a much more closely controlled
passband.


--
Woody

harrogate three at ntlworld dot com

In article , David Looser
wrote:
"tony sayer" wrote in message
...

You went involved in the MP2 codec tests for the development of DAB?..


No, voice codecs only, but the principle is the same. More to the point
I know just how hard it is, and the lengths we had to go to, to
eliminate bias from listening tests.

FWIW I've now had a chance to record some mp3 streams 'broadcast' by some
of the net stations. This meant I could write the results onto a CDRW and
listen to them on some players. Have examples at 128/192/256kbps. What I've
found interesting is that the results *didn't* show that the 'higher the
bitrate the better the sound'. This was a totally uncontrolled test, so is
suspect, but it does strengthen my bias towards feeling that the way the
specific encoder is used (and the details of the sound patterns to be
encoded) can matter more that the output bitrate chosen.

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article ,
Woody wrote:
Rubbish!. AM radio was downgraded by reducing it's bandwidth from 9kHz
to
4.5kHz betwen the 1930s and the 1960s.


Could you qualify that please?
AM radio, AFAIK, has always has an audio frequency response limit of
4KHz which means it needs an RF bandwidth of 8KHz. The station spacing
is thus set at 9KHz to (theoretically) leave a guard band between
stations. In practice for most domestic radios this is of little
consequence as it would be nigh impossible to hear two stations on
adjacent frequencies - something that would be possible on a
commercial/professional receiver with a much more closely controlled
passband.

Not so - the changes making the 9 kHz an international standard came in on
IIRC the early '70s. When R1 started up in the London area the 247 metre
transmissions had a bandwidth exceeding 12 kHz - the landline feeding that
transmitter was also wide band. With a good AM receiver the frequency
response didn't sound much different to FM when R1&2 did simulcasts.

--
*Nostalgia isn't what is used to be.

Dave Plowman London SW
To e-mail, change noise into sound.