From alsa-devel-owner@alsa.jcu.cz  Sat Jan 23 12:36:42 1999
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From: "Richard W.E. Furse" <richard@muse.demon.co.uk>
To: "'alsa-devel@alsa.jcu.cz'" <alsa-devel@alsa.jcu.cz>,
        "'sailer@ife.ee.ethz.ch'" <sailer@ife.ee.ethz.ch>
Subject: RE: hi-res pcm sound support/IEEE floats
Date: Sat, 23 Jan 1999 11:26:44 -0000
Reply-To: alsa-devel@alsa.jcu.cz
Sender: alsa-devel-owner@alsa.jcu.cz
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Hmmm. Absolutely right of course--I've reread the docs to work out how on Earth I came to my earlier conclusions! Many apologies.

However floats are still the way to go by the S/N arguments at least...

-- Richard

-----Original Message-----
From:	Thomas Sailer [SMTP:sailer@ife.ee.ethz.ch]
Sent:	Thursday, January 21, 1999 12:17 PM
To:	alsa-devel@alsa.jcu.cz
Subject:	Re: hi-res pcm sound support/IEEE floats

"Richard W.E. Furse" wrote:

> ARGUMENT 3 (The Done Thing)
> 
> Last time I looked at DSPs etc, they also used floats (IEEE floats)
> internally. I believe most of the Motorola chips do, the Intel FPUs and MMX

Wrong. Motorola's only DSP that could do FP in hardware was the 96000,
and AFAIK it is no longer available. Motorolas popular DSPs for Audio
are the 56000 and 56300, both 24bit fixed point machines (with 56bit
accumulators).

Also wrong is that MMX uses FP, MMX only uses very small integers,
up to 16bits or so. Therefore, MMX is mostly useless for anything
else than a few image processing algorithms.

> 32bit float = 24bit(linear) + 8bit(exponent). Best of all worlds, and
> probably what the DSP on your sound card is using anyway.

Show me one single soundcard (below 500$) that can do _anything_
with floats.

Tom
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