soundcard trouble with Wolf

[Bob Bruhns]

Andre - it's posting, it's posting!!!  - must be a problem with
auto-forward, or maybe it's out of control from the source.  - Bob

----- Original Message -----
From: "Andre' Kesteloot" <andre.kesteloot@ieee.org>
To: "AMRAD Tacos" <tacos@amrad.org>; "lf-amrad" <lf@amrad.org>
Sent: Wednesday, April 18, 2001 8:14 AM
Subject: soundcard trouble with Wolf


>
>
> Alberto di Bene wrote:
>
> > DL4YHF@aol.com wrote:
> > >
> > [snip]
> > > The precise sample rates of the soundcard, running at a
nominal sample rate
> > > of 8000 samples per second, were **DIFFERENT** for TX (D/A
conversion) and RX
> > > (A/D conversion)  !
> > [snip]
> >
> > Wolf and the group,
> >      in the Windows world a new standard is emerging, the AC97
standard for
> > sound cards. How does that affect us ? With AC97, the hardware
samples *always*
> > at the maximum sampling rate of 44.1 or maybe 48 kHz.
> > When a program opens the sound subsystem specifying a different
sampling rate,
> > the driver does a downsampling of the 44.1 (48) kHz stream when
opening for input,
> > and an upsampling, probably with zero-padding, when opening for
output.
> >
> > I have verified this in practice. On my IBM Thinkpad, I am able
to start
> > simultaneously several programs that use the sound card (sound
chip in this case),
> > and they work correctly even if they specify different sampling
rates !
> > At first I didn't believe to my eyes, but then I read about the
AC97 standard.
> >
> > The implications of this are that in the process of down/up
sampling, some roundoff
> > errors can happen, and the actual sampling rate, as seen by the
application,
> > can differ by a slight amount from what specified. For the
normal use of the
> > sound cards, i.e. games, this has no consequences. Not so for a
more serious use.
> > So the advice is to stay away, whenever possible, from sound
cards whose drivers
> > implement the AC97 standard, which, I'm afraid, is what Bill
want us to use.
> >
> > 73  Alberto  I2PHD
>
>
>
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