From alsa-devel-owner@alsa.jcu.cz  Wed Jul 22 22:44:15 1998
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Date: Wed, 22 Jul 1998 22:22:58 +0200
From: Marcus Brinkmann <Marcus.Brinkmann@ruhr-uni-bochum.de>
To: alsa-devel@jcu.cz, Thomas Sailer <sailer@ife.ee.ethz.ch>
Subject: Re: ALSA driver 0.2.0-pre2
References: <35B303E7.E9ECFBB7@ife.ee.ethz.ch> <Pine.LNX.3.96.980720112358.22254F-100000@entry.jcu.cz>
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In-Reply-To: <Pine.LNX.3.96.980720112358.22254F-100000@entry.jcu.cz>; from Jaroslav Kysela on Mon, Jul 20, 1998 at 11:33:57AM +0200
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On Mon, Jul 20, 1998 at 11:33:57AM +0200, Jaroslav Kysela wrote:
> On Mon, 20 Jul 1998, Thomas Sailer wrote:
> 
> > > soundcards. Write kernel-side mixing PCM module (mixing will be done
> > > probably in kernel thread).
> > 
> > Including sample rate conversion?
> 
> Yes, but very simple. I'm planning only simple support downmix/upmix to
> 1/2, 1/4 etc.. For example if mixing rate (user selectable) will be
> 44100Hz, only rates 44100,22050,11025,5512 will be supported. Looks like
> there will be big problem with 8000Hz frequency (for .au playback and
> RAT).

Mmmh.

Isn't converting to different sample rates the same as drawing a straight line
on bit planes?

The Bresenham algorithm has a nice integer solution for this. I can work out
the details, if you want. It wouldn't be too time consuming, I think.
(Maybe you want to do this in libraries user space, though).

Marcus

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