DAB R3 balance
 

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

If you want to compare results with me then do the following:

Erm... what OS, etc, are you assuming I am using? :-)

* download Lame v3.90.3:

[snip]


You would need to direct me at a version that runs under RO on an
ARM-core CPU and which can be verified to act identically to the
one you use. However even if that were done and I had the time
to try it...


Okau, I'll just tell you the results I've had when I've done this in the
past. I recorded Radio 1 and Radio 3 off DTT and re-compressed
(transcoded) to VBR MP3 at a given quality and the classical music on R3
required a lower bit rate than R1.

Also, yesterday I encoded Morrissey's and Snow Patrol's most recent
albums, the latter because it's got quite a bit of the loud electric
guitars I mentioned, and the former because I've been playing about with
the new HE AAC codec recently and it suffers badly when starved of bits.
Both albums required a bit rate significantly higher than the norm for
that VBR quality setting.


It isn't clear to me what value the process you suggest would have
w.r.t the issues we were discussing in terms of the differences
between what the BBC do for R1/2 and R3.


If you had paid attention, I described a way of comparing difficulty of
encoding by comparing NMR (noise to mask ratio), and encoding using VBR
for a given quality setting will try to set the NMR to be relatively
constant -- MP3 encoders iteratively allocate bits to minimise the NMR
(or equivalently, maximise the mask to noise ratio).


If you wish to support your
argument for that then I'd assume you need to do so in terms of the
specifics of
the BBC signals and waveforms.


To prove this you don't need BBC signals or waveforms, you just have to
show that flatter spectra are more difficult to encode.


The snag being that to do so you
ideally may need access to the originals before they were level
compressed
and data reduced.


No, I wouldn't need access to the originals.


AIUI your point was based on argueing that the R1/R2 typical signals
have a more unform and flatter spectrum. My point was that it may
also depend on the number of spectral components, not just the
uniformity and range of those present.


A totally flat and very wide spectrum is bound to end up with more
frequency components post-masking than one that tails off far faster and
isn't as broad. It's an assumption, but a very, very good one. I'm sure
you've used far weaker assumptions before than the one I'm using.....


Without access to the BBC
original waveforms and their level compression, etc, how would
my attempting to use Lame establish this?


See above.

I'm going away for the weekend, so I won't be able to reply to any
further posts until I'm back.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview, DAB & MP3 Player Prices:
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http://www.digitalradiotech.co.uk/mp...e_capacity.htm

DAB R3 balance
 

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

If you want to compare results with me then do the following:

Erm... what OS, etc, are you assuming I am using? :-)

* download Lame v3.90.3:

[snip]


You would need to direct me at a version that runs under RO on an
ARM-core CPU and which can be verified to act identically to the one
you use. However even if that were done and I had the time to try it...


Okau, I'll just tell you the results I've had when I've done this in the
past. I recorded Radio 1 and Radio 3 off DTT and re-compressed
(transcoded) to VBR MP3 at a given quality and the classical music on R3
required a lower bit rate than R1.

Afraid I don't know what definition you are using for 'quality' in the
above in terms of the actual amount of info discarded, and the judgement
rules used to discard components or increase their quantisation. Hence I'm
not clear how it would relate specifically to what the BBC do for R1/2/3
and the previous statements you have made.

Also, yesterday I encoded Morrissey's and Snow Patrol's most recent
albums, the latter because it's got quite a bit of the loud electric
guitars I mentioned, and the former because I've been playing about with
the new HE AAC codec recently and it suffers badly when starved of
bits. Both albums required a bit rate significantly higher than the
norm for that VBR quality setting.

What basis apart from your subjective judgement are you using for the
comments about "suffering" and "required a bit rate"?...

It isn't clear to me what value the process you suggest would have
w.r.t the issues we were discussing in terms of the differences
between what the BBC do for R1/2 and R3.


If you had paid attention,

sigh More irrelevant personal comments...

I described a way of comparing difficulty of encoding by comparing NMR
(noise to mask ratio), and encoding using VBR for a given quality
setting will try to set the NMR to be relatively constant -- MP3
encoders iteratively allocate bits to minimise the NMR (or equivalently,
maximise the mask to noise ratio).

But you seem not to have explained how this establishes your assertions
about R/1/2/3 specifically are correct.

If you wish to support your argument for that then I'd assume you need
to do so in terms of the specifics of the BBC signals and waveforms.


To prove this you don't need BBC signals or waveforms, you just have to
show that flatter spectra are more difficult to encode.

Again, this depends on the specific definition of 'flatter' and 'more
difficult'. As I think I pointed out in previous postings.

The snag being that to do so you ideally may need access to the
originals before they were level compressed and data reduced.


No, I wouldn't need access to the originals.


AIUI your point was based on argueing that the R1/R2 typical signals
have a more unform and flatter spectrum. My point was that it may also
depend on the number of spectral components, not just the uniformity
and range of those present.


A totally flat and very wide spectrum is bound to end up with more
frequency components post-masking than one that tails off far faster and
isn't as broad. It's an assumption, but a very, very good one. I'm sure
you've used far weaker assumptions before than the one I'm using.....

I would agree if by "totally flat" you mean much the same level at *every*
frequency in the spectrum for the relevant time frame. However the point I
was asking about was how you know this is the case for the R1/2 signals
before they are data reduced. Again, I was trying to distingish this from
the orginal having a number of components of a given, similar level, but
spread across the band with other components at lower levels. So far as I
can tell, you have not so far dealt with this distinction in your replies.
My apologies if I have missed it. If so, please indicate the relevant
posting and I'll re-read it if it is still in scope of my newagent's time
limit.

Without access to the BBC original waveforms and their level
compression, etc, how would my attempting to use Lame establish this?


See above.

See above. :-)

I'm going away for the weekend, so I won't be able to reply to any
further posts until I'm back.

OK.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

DAB R3 balance
 

On Thu, 17 Feb 2005 15:54:50 +0000, Jim Lesurf wrote:


If you want to compare results with me then do the following:

Erm... what OS, etc, are you assuming I am using? :-)

* download Lame v3.90.3:

[snip]

As far as I know Lame is available for Windows, Linux, Open BSD
and Free BSD. When it comes to Macs I don't know. Same for Sun
Solaris.

And then you have ogg-vorbis if you don't feel like finding sneaky
ways around the copyright of mp3.

--
================================================== ==================
Martin Schöön * * * * * * * * * *"Problems worthy of attack
* * * * * * * * * * * * * * * * * prove their worth by hitting back"
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Piet Hein
================================================== ==================

DAB R3 balance
 

In article , Martin Schöön
wrote:
On Thu, 17 Feb 2005 15:54:50 +0000, Jim Lesurf wrote:


If you want to compare results with me then do the following:

Erm... what OS, etc, are you assuming I am using? :-)

* download Lame v3.90.3:

[snip]

As far as I know Lame is available for Windows, Linux, Open BSD and Free
BSD. When it comes to Macs I don't know. Same for Sun Solaris.

However:

1) The OS I use most of the time is not on the above list. :-)

2) I doubt the exe files, etc, that were quoted would run on my (ARM core
CPU) machine.

Lame may well be available for the OS I mostly use. FWIW I also use Solaris
and even (rarely) Windows at times. But in the context of this thread what
I said later in the previous postings seems appropriate to me. Hence I
haven't bothered to try and get a version of Lame working as yet.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

DAB R3 balance
 

On Sat, 19 Feb 2005 09:33:59 +0000, Jim Lesurf wrote:


2) I doubt the exe files, etc, that were quoted would run on my (ARM core
CPU) machine.

Since Lame is an open source development project you could always
download source code... The same goes for ogg I think.

Lame may well be available for the OS I mostly use. FWIW I also use Solaris
and even (rarely) Windows at times. But in the context of this thread what
I said later in the previous postings seems appropriate to me. Hence I
haven't bothered to try and get a version of Lame working as yet.

Wel, who knows? All of a sudden you might change your mind :-)
--
================================================== ==================
Martin Schöön * * * * * * * * * *"Problems worthy of attack
* * * * * * * * * * * * * * * * * prove their worth by hitting back"
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Piet Hein
================================================== ==================

DAB R3 balance
 

In article , Martin Schöön
wrote:
On Sat, 19 Feb 2005 09:33:59 +0000, Jim Lesurf wrote:


2) I doubt the exe files, etc, that were quoted would run on my (ARM
core CPU) machine.

Since Lame is an open source development project you could always
download source code... The same goes for ogg I think.

IIRC Ogg has been ported to the OS I use. I suspect that Lame has as well,
but am far from sure. Afraid I've never ported anything to my main OS so
don't know if I would find this easy/convenient.



Lame may well be available for the OS I mostly use. FWIW I also use
Solaris and even (rarely) Windows at times. But in the context of this
thread what I said later in the previous postings seems appropriate to
me. Hence I haven't bothered to try and get a version of Lame working
as yet.

Wel, who knows? All of a sudden you might change your mind :-)

Erm... About what? :-) The reason I have not done so (as yet) is that
what 'DAB' suggested wrt to my using 'Lame' does not (yet) seem relevant to
answering the question(s) I was putting to him. And don't have any real
interest in storing/using audio in data-reduced formats or on my computers.
However if either of these factors altered, I might then become more
interesting in experimenting with 'Lame'.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

DAB R3 balance
 

In article ,
Jim Lesurf wrote:
Lame may well be available for the OS I mostly use. FWIW I also use
Solaris and even (rarely) Windows at times. But in the context of
this thread what I said later in the previous postings seems
appropriate to me. Hence I haven't bothered to try and get a version
of Lame working as yet.

Wel, who knows? All of a sudden you might change your mind :-)

Erm... About what? :-) The reason I have not done so (as yet) is that
what 'DAB' suggested wrt to my using 'Lame' does not (yet) seem relevant
to answering the question(s) I was putting to him. And don't have any
real interest in storing/using audio in data-reduced formats or on my
computers. However if either of these factors altered, I might then
become more interesting in experimenting with 'Lame'.

The other beauty of RISC OS is that no-one can be bothered to write worms
or viruses for it - and even if they did, having a ROM based OS makes it
impossible to corrupt in a terminal way.

--
*Learn from your parents' mistakes - use birth control

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