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Willem · Guest

ChrisCoaster wrote:
) The audio CD sample rate is set at 44,000Hz(44kHz) for a simple
) reason: Two channels - Left, Right, A,B, whatever you want to call
) them. Each channel gets up to 22kHz.

Where/who did you get that ridiculous idea from ?

SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I>m not paranoid. You all think I>m paranoid, don>t you !
#EOT

Richard Crowley · Guest

"ChrisCoaster" wrote ...
[quote]Very simple. CDs have two channels of sound: Left, Right, A, B, 1, 2,
whatever you want to call them. L22kHz + R22kHz = 44kHz.
[/quote]
Absolutely not. Each channel is sampled at 44.1KHz.
There is no "L22KHz + R22KHz = 44KHz".

Chronic Philharmonic · Guest

"geoff" <geoff@nospam-paf.co.nz> wrote in message
news:jdOdnSNoyt34c-_VnZ2dnUVZ_vadnZ2d@giganews.com...
[quote]Earl Kiosterud wrote:
I notice that Audacity displays sample points connected with straight
lines. I don>t think that>s meaningful. Other editors show what a
post-filter, presumably at 20 KHz, would show, along with the sample
points.

That would be very presumptive of editing software. SOundForge shows
straight lines between samples - I would be most peeved if SF made an
arbitrary decision about a filter.
[/quote]
If they>re drawing lines between samples, they>re making arbitrary decisions
about filters. They should either be properly smoothing the waveform (they
know the sample rate don>t they?), or showing a histogram, in my opinion.

Mr.T · Guest

"geoff" <geoff@nospam-paf.co.nz> wrote in message
news:ue2dneLYed1AdO7VnZ2dnUVZ_qPinZ2d@giganews.com...
[quote]Phase linear response does not give sufficient audible advantages to
offset the difficulty of building loudspeakers that have it.

I want a phase-linear room.
[/quote]
Or even a frequency linear room!

MrT.

Mr.T · Guest

"Richard Crowley" <rcrowley@xp7rt.net> wrote in message
news:AredncgU06sW3-nVnZ2dnUVZ_szinZ2d@posted.pcez...
[quote]ChrisCoaster" wrote ...
Very simple. CDs have two channels of sound: Left, Right, A, B, 1, 2,
whatever you want to call them. L22kHz + R22kHz = 44kHz.

Absolutely not. Each channel is sampled at 44.1KHz.
There is no "L22KHz + R22KHz = 44KHz".
[/quote]
You could argue that since each channel is sampled at 44.1kHz, and the data
is interleaved, then the total sample rate is "sort of" equal to 88.2kHz.
Not that *I* would though :-)

MrT.

Industrial One · Guest

On Jul 8, 11:22 pm, Willem <wil...@stack.nl> wrote:
[quote]ChrisCoaster wrote:

) The audio CD sample rate is set at 44,000Hz(44kHz) for a simple
) reason: Two channels - Left, Right, A,B, whatever you want to call
) them. Each channel gets up to 22kHz.

Where/who did you get that ridiculous idea from ?

SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I>m not paranoid. You all think I>m paranoid, don>t you !
#EOT
[/quote]
That>s what I>d like to know. Also, that guy replied to his own post
twice. Is it just me or is Chris talking to himself? What you been
smokin' bud?

Pete Fraser · Guest

"Mr.T" <MrT@home> wrote in message
news:48746dc9$0$30466$afc38c87@news.optusnet.com.au...

[quote]You could argue that since each channel is sampled at 44.1kHz, and the
data
is interleaved, then the total sample rate is "sort of" equal to 88.2kHz.
[/quote]
If I (or anyone) did, they>d be very wrong.

ChrisCoaster · Guest

On Jul 9, 10:51 am, Industrial One <industrial_...@hotmail.com> wrote:
[quote]On Jul 8, 11:22 pm, Willem <wil...@stack.nl> wrote:

ChrisCoaster wrote:

) The audio CD sample rate is set at 44,000Hz(44kHz) for a simple
) reason: Two channels - Left, Right, A,B, whatever you want to call
) them. Each channel gets up to 22kHz.

Where/who did you get that ridiculous idea from ?

SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I>m not paranoid. You all think I>m paranoid, don>t you !
#EOT

That>s what I>d like to know. Also, that guy replied to his own post
twice. Is it just me or is Chris talking to himself? What you been
smokin' bud?
____________________[/quote]
Smokin'?? I think you must have me confused with the WhiteHouse.

Go back and read my posts from late tuesday night; I did apologize to
Usenet viewers if it appeared I was double/triple posting. I use
Google Groups, not Usenet, to post to and read newsgroups, and lately
Google>s been nothing short of a cluster#uck as far as how quickly it
relays my posts - if at all!

On Topic: If someone can explain the 44.x sampling rate of CDs to
someone whose math skills are limited to adding/subracting whole
numbers, it would be appreciated. My idea that 44kHZ was space enough
to contain 22kHZ for two stereo channels was obviously wrong, and
something I would like clarified/corrected after having believed it
for 20 years now.

Thanks,

-CC

Guest · Posted: Wed Jul 09, 2008 10:05 pm Post subject: Re: Frequency/Sample rate

On Jul 9, 4:43 pm, ChrisCoaster <ckozi...@snet.net> wrote:
[quote]The audio CD sample rate is set at 44,000Hz(44kHz) for a simple
reason: Two channels - Left, Right, A,B, whatever you want to call
them. Each channel gets up to 22kHz.

Where/who did you get that ridiculous idea from ?
On Topic: If someone can explain the 44.x sampling rate of
CDs to someone whose math skills are limited to adding/
subracting whole numbers, it would be appreciated. My
idea that 44kHZ was space enough to contain 22kHZ for
two stereo channels was obviously wrong, and something
I would like clarified/corrected after having believed it for
20 years now.
[/quote]
There are plenty of references on the net and in print
that have been around for at least 25 years that explained
what was going on. You never tested whether your idea
corresponded with reality until now. And it didn;t match.

Fine. You can now take what I say can compare it to,
oh IEC 60958, for example, or the original Philips/Sony
red book CD standard. Check out Pohlmann>s
Principles of Digital Audio, somewhat more widely available.,

But here>s the scoop. A SINGLE channel, sampled at 44.1
kHz, is, itself, for the reasons stated earlier capable of
providing a bandwidth of less than 22.05 kHz. Now, if you
want STEREO, you>re going to have to have TWO channels
with that bandwidth, you will need TWICE as many samples:
on for the left, one for the right, EACH at 44.1 kHz.

In the techncial parlance used by IEC 60958, each SAMPLE
consists of a 16-bit integer sample value, and is held in a
"subframe". a left sample and a right sample together, two
subframes, constitutes a "frame", and CD audio has 44,100
frames (each holding TWO samples) per second.

The resulting data rate of CD audio, then, is

16 bits/subframe * 2 subframes/frame * 44100 frames/sec

1,411,200 bits per second. Assuming 8 bits/byte, that>s
176,400 bytes/second, and given the rec book limit of
74 minutes, that>s 783,216,000 bytes/CD. And CDROMs
are about 750 MB in size, oh by the way.

Now, the issue of why 44,100 samples per second gives
you a bandwidth of less than 22,050 was first demonstrated
by Nyquist around 80 years ago, and the entire principles
relating to sampling, bandwidth, and such were cast in
mathematical rigor by Shannon over 55 years ago.

But the bottom line, and the answer to your idea, is this:
you want a channel whose bandwidth is 20 kHz? Then you
HAVE to sample it at a rate GREATER THAN TWICE the
bandwidth IF you want to capture the full bandwidth with no
loss.

44,100 samples per second will do that nicely when
implemented well.

You want TWO channels at 20 kHz bandwidth? EACH channel
has to be sampled at GREATER THAN TWICE the bandiwdth.
Now you have twice as much data.

Is the sample rate now 88.2 kS/sec? No, it>s TWO channels
at 44.1 kS/sec.

However, you COULD (and people HAVE) for special purposes,
us a CD to store a SINGLE channel smapled at 88.2 kS/sec
to achieve a SINGLE CHANNEL bandwidth of about 40 kHz.

No, it>s not 44.1 kHz because you have two 22.05 kHz channels.
It>s two independent 44.1 kHz channels.

geoff · Guest

Chronic Philharmonic wrote:
[quote]"geoff" <geoff@nospam-paf.co.nz> wrote in message
news:jdOdnSNoyt34c-_VnZ2dnUVZ_vadnZ2d@giganews.com...
Earl Kiosterud wrote:
I notice that Audacity displays sample points connected with
straight lines. I don>t think that>s meaningful. Other editors
show what a post-filter, presumably at 20 KHz, would show, along
with the sample points.

That would be very presumptive of editing software. SOundForge shows
straight lines between samples - I would be most peeved if SF made an
arbitrary decision about a filter.

If they>re drawing lines between samples, they>re making arbitrary
decisions about filters. They should either be properly smoothing the
waveform (they know the sample rate don>t they?), or showing a
histogram, in my opinion.
[/quote]
Naa , a line is important in case you miss a sample dot out of field of
veiw. Histogram just plain messy, and how thick would you make the columns ?

geoff

Richard Crowley · Guest

"ChrisCoaster" wrote ...
[quote]On Topic: If someone can explain the 44.x sampling rate of CDs to
someone whose math skills are limited to adding/subracting whole
numbers, it would be appreciated. My idea that 44kHZ was space enough
to contain 22kHZ for two stereo channels was obviously wrong, and
something I would like clarified/corrected after having believed it
for 20 years now.
[/quote]
For RedBook standard CDs, the sample frequency (Fs)
is 44.1KHz by definition. The same definition also says
that audio CDs will have two channels, not more, and not
less (unfortunately). All CDs must conform to this standard
or they will not be playable on CD players.
http://en.wikipedia.org/wiki/Red_Book_%28audio_CD_standard%29

In very general terms a digital sample stream of frequency Fs
can accurately sample frequencies up to Fs/2 (1/2 of Fs)
http://en.wikipedia.org/wiki/Nyquist_rate

That means that theoretically, a 44.1KHz sample rate can
sample up to 22.05 KHz audio.

Stereo is 2 channels. That means that there are actually
Fs*2 samples per second (88.2K samples per second)

Willem · Guest

ChrisCoaster wrote:
) On Topic: If someone can explain the 44.x sampling rate of CDs to
) someone whose math skills are limited to adding/subracting whole
) numbers, it would be appreciated. My idea that 44kHZ was space enough
) to contain 22kHZ for two stereo channels was obviously wrong, and
) something I would like clarified/corrected after having believed it
) for 20 years now.

Easy:

If you have a sound with a frequency of 20kHz, that means that the wave has
to go through one complete cycle 20.000 times a second. That is: up *and*
down 20.000 times a second. To record that you need to record both the ups
and the downs, so that>s 20.000 ups plus 20.000 downs, makes 40.000 samples
per second.

Why they went up from 40kHz to 44.1kHz is some weird technical reason,
explained in another part of this thread.

SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I>m not paranoid. You all think I>m paranoid, don>t you !
#EOT

Mr.T · Guest

"Pete Fraser" <pfraser@covad.net> wrote in message
news:f4Odnbbjz--HL-nVnZ2dnUVZ_hninZ2d@supernews.com...
[quote]You could argue that since each channel is sampled at 44.1kHz, and the
data
is interleaved, then the total sample rate is "sort of" equal to
88.2kHz.
Not that *I* would though :-)

If I (or anyone) did, they>d be very wrong.
[/quote]
But they would not necessarily be "very wrong", simply using a non standard
definition, which is all too common on these newsgroups.
Like you it seems, I prefer to stick with what is technically correct using
standard definitions though.
I do find endlessly arguing definitions and semantics tedious however.

MrT.

ChrisCoaster · Guest

On Jul 10, 1:50 am, Willem <wil...@stack.nl> wrote:
[quote]ChrisCoaster wrote:

) On Topic: If someone can explain the 44.x sampling rate of CDs to
) someone whose math skills are limited to adding/subracting whole
) numbers, it would be appreciated. My idea that 44kHZ was space enough
) to contain 22kHZ for two stereo channels was obviously wrong, and
) something I would like clarified/corrected after having believed it
) for 20 years now.

Easy:

If you have a sound with a frequency of 20kHz, that means that the wave has
to go through one complete cycle 20.000 times a second. That is: up *and*
down 20.000 times a second. To record that you need to record both the ups
and the downs, so that>s 20.000 ups plus 20.000 downs, makes 40.000 samples
per second.

Why they went up from 40kHz to 44.1kHz is some weird technical reason,
explained in another part of this thread.

SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I>m not paranoid. You all think I>m paranoid, don>t you !
#EOT
_________________[/quote]
Thanks Willem! You are the only one to finally clarify this in
ENGLISH(remember I can barely add 2+2).

As for that 44kHz bit, there are some people out there who hear like
dogs; that is they can sense sounds equal to or greater than 20kHz.
The designers of the CD standard probably chose 22kHz because a CD>s
freq response actually drops off like the Cayman Wall at the ends of
it>s specified range, due to its digital nature. Unlike analog, which
"rolls" off gradually at varying rates, subject to source. So they
figured, move that Cayman Wall slightly above 20kHz to ensure that
99.999999% of musical content gets on the disc. Hence, 22kHz. So now
you have the high & low portions of soundwaves up to 22kHz = 44.1(to
be exact)kHz!

-CC

Guest · Posted: Thu Jul 10, 2008 12:16 pm Post subject: Re: Frequency/Sample rate

On Jul 10, 7:29 am, ChrisCoaster <ckozi...@snet.net> wrote:
[quote]On Jul 10, 1:50 am, Willem <wil...@stack.nl> wrote:

ChrisCoaster wrote:

) On Topic: If someone can explain the 44.x sampling rate of CDs to
) someone whose math skills are limited to adding/subracting whole
) numbers, it would be appreciated. My idea that 44kHZ was space enough
) to contain 22kHZ for two stereo channels was obviously wrong, and
) something I would like clarified/corrected after having believed it
) for 20 years now.

Easy:

If you have a sound with a frequency of 20kHz, that means that the wave has
to go through one complete cycle 20.000 times a second. That is: up *and*
down 20.000 times a second. To record that you need to record both the ups
and the downs, so that>s 20.000 ups plus 20.000 downs, makes 40.000 samples
per second.

Why they went up from 40kHz to 44.1kHz is some weird technical reason,
explained in another part of this thread.

SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I>m not paranoid. You all think I>m paranoid, don>t you !
#EOT

_________________
Thanks Willem! You are the only one to finally clarify this in
ENGLISH
[/quote]
Except that the explanation, while seemingly intuitively
correct, is misleading. Among other things, it assumes
that the waveform IS sinsusoidal AND that it has "ups
and downs". It doesn>t have to, and, in fact, the signal
could consist of only differeing "ups".

[quote](remember I can barely add 2+2).
[/quote]
Then if you insist on casting everything into a 2nd grade
mathematical vocabulary, you>re guaranteed to get it
wrong, wven when any number of people try patiently
to explain to you that a 2+2 understanding isn>t going to
cut it.

[quote]As for that 44kHz bit, there are some people out there who hear like
dogs; that is they can sense sounds equal to or greater than 20kHz.
The designers of the CD standard probably chose 22kHz because a CD>s
freq response actually drops off like the Cayman Wall at the ends of
it>s specified range, due to its digital nature. Unlike analog, which
"rolls" off gradually at varying rates, subject to source.
[/quote]
Wrong. The "sampling" portion is not in the least bit
"digital", in fact, the sampler can be PURELY analog.
One very practical example is the old analog bucket-
brigade delay lines, which absolutely HAD to have
a brick-wall ANALOG anti-aliasing feature. Another
example is switched-capacitor filters: the signals
are PURELY analog, but discrete-time sampled, and
thus absolutely REQUIRE a brick-wall ANALOG filter
to prevent aliasing.

Yet another example is found in sampling oscilloscopes,
technology which comes from well before 1970. The
fignals are purely ANALOG in a discrete-time analog system.

And guess what? That brick wall ANALOG filter has
to be placed at LESS THAN TWICE THE SAMPLING
RATE to prevent aliasing. The exception is in the case
of the sampling oscilloscope which DELIBERATELY
aliases a very high frequency down to the base band.

[quote]So they
figured, move that Cayman Wall slightly above 20kHz to ensure that
99.999999% of musical content gets on the disc. Hence, 22kHz.
So now
you have the high & low portions of soundwaves up to 22kHz = 44.1(to
be exact)kHz!
[/quote]
Did you bother AT ALL, to read some of the posts,
including my own, which addressed QUITE SPECIFICALLY
where the 44.1 kHz sample rate came from?

They could have done 40 kHz, 45 kHz, 50 kHz. Some for the
broadcast industry even do 32 kHz sample rates.

But the ONLY reason 44.1 kHz was chosen was because
the ONLY high-speed storage and transmission medium
that was readily available at the time (late 1970>s) for
digital audio was video tape recorders. And based on the
NTSC frame rate (60 Hz), the number of scan lines per frame
(525), the number of blanked lines per frame (35) leading
to 490 available lines per field or 245 per frame) and the
video bandwidth adequate for the bit rate which lead to putting
3 sample PAIR per scan line leads to:

60 * 245 * 3 = 44100 sample PAIRS per second

On 50 Hz video, a similar calculation based on 625/50 Hz
with 37 blanked lines leads to:

50 * 294 * 3 = 44100 sample PAIRS per second

You can hold on to your "Cayman cliff" understanding if
it feels right for you, but you>d be wrong. 44.1 kHz was
chosen for the reasons given here. Period. It>s not a
debatable point, it>s not subject to what you think you
can or cannot understand, it>s a matter of established
technical and historicl fact.

You don>t like that explanation? YOu can get your
arms around it? Fine, go rewrite history and change
physics while you>re at it. Good luck with that.


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