David Fontaine wrote:
>...
> And records sound better <g> ;)

I think that the lowest bass frequencies on a 
vinyl is only recorded in mono.


> Now if they could just make records that last a decent number of
> playings...

If you read the vinyl optically it will last 
much longer.


-- 
Best regards,

Tor Olav

mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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Ron Parker wrote:
> 
> On Mon, 29 Jan 2001 22:52:47 -0600, David Fontaine wrote:
> >Aside from that, any mathematician will tell you the sample rate is
> >insufficient. The highest frequency a person can hear is around 20kHz. The
> >sample rate of a CD is 44kHz. It should be at least double that, 5x the
> >highest frequency. Think about it, you could be sampling near the zero
> >point every time.
> 
> Careful... I am a mathematician, though I don't practice anymore.  The
> Nyquist Theorem says a sampling frequency of twice the highest expected
> frequency is sufficient to recreate anything at or below that expected
> frequency.  Thus, CDs can accurately reproduce sounds at 22050 Hz and
> below.
> 
> It is important, though, to filter out anything above 22050 Hz before
> the digitizing stage, due to aliasing.  I suspect most professionals do
> so as a matter of course.

Careful... I am a "electronician", though I don't practice analog 
electronics anymore.  ;-)

This is one of the problems with CD players:

It's difficult to design good and cheap 
filters that has a very sharp cut-off 
frequency that lies right above this 
22 kHz frequency.

But if the sampling frequency had been chosen 
higher for CD's, then one could have used 
cheaper and more "relaxed" filters with higher 
cut off frequencies that would not make 
distortions to the sound (within the "audible"
range).


-- 
Best regards,

Tor Olav

mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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On Tue, 30 Jan 2001 21:21:10 +0100, Tor Olav Kristensen wrote:
>> Now if they could just make records that last a decent number of
>> playings...
>
>If you read the vinyl optically it will last 
>much longer.

Unfortunately, without the needle to push the dust out of the way,
they also sound much worse.

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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On Tue, 30 Jan 2001 21:37:57 +0100, Tor Olav Kristensen wrote:
>This is one of the problems with CD players:

Not with CD players, per se, since the filtering should happen in the 
studio, but it is a problem.

>It's difficult to design good and cheap 
>filters that has a very sharp cut-off 
>frequency that lies right above this 
>22 kHz frequency.

I'd considered mentioning that, but left it out so as to not make an 
already off-topic conversation even more so.  (I don't have a degree
or anything in electronics, but the FCC did see fit to grant me a 
radio amateur's license lo these many years ago.)

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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in <slr### [at] fwicom> Ron Parker wrote:

>Unfortunately, without the needle to push the dust out of the way,
>they also sound much worse.

What? You don't have a Nitty Gritty Record Cleaning Machine??

http://www.lowther.nl/wwwpages/nitty.html

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/

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Ron Parker wrote:
> 
> On Tue, 30 Jan 2001 21:37:57 +0100, Tor Olav Kristensen wrote:
> >This is one of the problems with CD players:
> 
> Not with CD players, per se, since the filtering should happen in the
> studio, but it is a problem.

You may search for the this sentence:

"The need for placing a filter after the DAC in 
the player may not be intuitively obvious."

(Within the Aliasing section.)

at this page:

http://www.totse.com/en/technology/science_technology/cd_audio.html

to get an explanation of why such a filter
also are necessary in a CD-player.


> >It's difficult to design good and cheap
> >filters that has a very sharp cut-off
> >frequency that lies right above this
> >22 kHz frequency.

But I wasn't quite right about it STILL 
being difficult to perform this filtering 
in todays CD players. (See the "Digital-to
-analog Converters" section in the same 
document.)

DSPs seems to be the solution now.


Best regards,

Tor Olav

mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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Ron Parker wrote:

> Careful... I am a mathematician, though I don't practice anymore.  The
> Nyquist Theorem says a sampling frequency of twice the highest expected
> frequency is sufficient to recreate anything at or below that expected
> frequency.

I don't buy it.

http://members.aol.com/ajaynejr/nyquist.htm

This is about video but much of it can apply to audio as well.

--
David Fontaine  <dav### [at] faricynet>  ICQ 55354965
My raytracing gallery:  http://davidf.faricy.net/

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Warp wrote:
> 
>   Is it worth the efforts to make this huge amount of work just to
> optimize one executable binary for one CPU?

As someone who owns an Athlon machine I consider that a silly question :)

Besides there are now more than just one person using this CPU. Lots of
people are buying them.

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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I often have to finish all part of my code or the next day I show up at work
I spend a few hours just to get the hang of where I was..............

BR.Saadat

"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3A76F066.BDA07E2F@gmx.de...
>
>
> Ron Parker wrote:
> >
> > There's nothing in there that nobody on the POV-Team understands.
Except
> > for the occasional "I don't understand why they did it this way" sort.
> >
>
> I concluded that from the discussion about the mesh code / tesselation
> patch.
>
> Anyway i think 'understanding' is quite a non precise word when talking
> about programming.  I often don't understand code i wrote 5 days ago :-)
>
> Christoph
>
> --
> Christoph Hormann <chr### [at] gmxde>
> IsoWood include, radiosity tutorial, TransSkin and other
> things on: http://www.schunter.etc.tu-bs.de/~chris/

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Alessandro Coppo <a.c### [at] iolit> wrote:
: Was ever POV put under profiling to look for hotspots?

  I have done that, but didn't find anything easy to optimize.

  Perhaps I'll try it again some day.

: P.S.: I once read some C code and asked myself who had been so idiot to
: write it that way. After a few seconds, I remebered. It was me.... six
: months before.

  This happens probably to almost everyone. In a half year you learn so much
that you would have done the same code much better if you had known.

-- 
char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););}    /*- Warp -*/

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