In article , DAB sounds worse than
FM wrote:
Jim Lesurf wrote:
In article , DAB sounds worse
than FM wrote:
Jim Lesurf wrote:
In article , DAB sounds worse
than FM wrote:


Because Radios 1 & 2 and all the pop stations have audio processing
applied then the spectrum tends to be wide and flat, which tends to
result in aa lot of remaining frequency components after the
psychoacoustic model has produced the masking curves to throw away
the inaudible subbands.

Is that the case in the timescales relevant for the data reduction
'frames' (or whatever the correct term is)? I can see that R1/2 tend
to use audio 'compression' (in the old sense) and this may work to
flatten the medium term power spectrum. However that does not in
itself mean the spectrum is 'white' if it has a finite number of
components. Nor does it necessarily mean that each individual
processed time-frame will have a near uniform power spectral
density. Do you have some data on this relevant to R1/2?


No data; I've just looked at a lot of spectra. I know it's not white,
but it's a hell of a lot flatter and broader for R1/2 than R3. R3
tends to tail-off quickly, whereas R1/2 tails-off significantly
slower and for the vast majority of the time it goes right the way up
to the brickwall filter.

The difficulty is that doesn't necessarily lead to your conclusion.


Common sense dictates that it does.

I'm afraid that would only be so if the 'common sense' does not take into
acount the distinctions I was outlining. :-) Hence it would be like the
'common sense' that sometimes causes people to say all kinds of things
which may turn out to be incorrect. I am wary of conclusions "dictated" by
"common sense" as this often turns out to be a poor guide.


The spectral components present in any time frame may extend across a
wider range, and be more unform in size. But if the *number* of
components that are resolved in the time frame are sigificantly less,
then the 'weeding' process may lose less info. Impossible to assess
this without much more specific info than simply observing a tendency
for the components that are present to have similar levels, etc.

Hence I think the point you make is certainly an important one, but it
may not establish the conclusion you draw without more specific
evidence.


What I've heard over the last 3 years tell me that I'm right.

Or rather, leads you to *believe* you are right. :-)

Not saying you are wrong. Just saying 'dunno', but 'not proven' simply
from what you have said.


I cannot prove this with absolute certainty, but it's beyond reasonable
doubt IMO.

I note your opinion, but am trying to distinguish between opinions and
matters of fact.




If you can justify that to yourself as being fair then the only
conclusion I can come to is that you're extremely selfish.

Can't really comment on what may be 'fair' here. Just have an interest
in when the system may show audible problems. Since I don't listen
much to R1/2 (and never on DAB) I can't pass any comment on them one
way or the other.


Well I can, and they sound ****e, and it is unfair that they sound ****e
while R3 uses a 50% higher bit rate. Only a fascist would disagree.

Your comment seem to be in the spirit of the 'Ken Livingstone' school of
scientific discussion. :-)

FWIW in terms of *video* I have certainly seen very 'odd' effects at
times on BBCTV4 via DTTV. e.g. I have DVD+R's of one prom where the
'live' sic broadcast has a picture that 'stutters' throughout a
large part of the broadcast, but where the late-night repeat is fine.
I assume this was variable rate statmux stealing bitrate from BBCTV4


Probably. The BBC never alter the stat-mux bit rate allocations, which
is incredibly lazy, IMO.


during the evening to give to some other station(s), but a higher rate
being available after midnight for the repeat. Would not surprise me
if similar 'audio' crudities turned up on DAB at times.


I thought you were talking about video?

Depends what comments I made that you are referring to. I have made some
comments about the sound of R3 on 'Freeview'. I have made some comments
about the sound of BBCTV4 on Freeview. I have also made a comment about
the *video* on BBCTV4 on Freeview. How these may be related, though, I am
unsure. Only generalisation is that they all involve data-reduction
'compression' systems to communicate the information.

Slainte,

Jim

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