From alsa-devel-owner@alsa.jcu.cz  Sat Jan 23 19:35:05 1999
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Date: Sat, 23 Jan 1999 13:34:54 -0500 (EST)
From: Chris David <cdavid@umich.edu>
To: "'alsa-devel@alsa.jcu.cz'" <alsa-devel@alsa.jcu.cz>
Subject: RE: hi-res pcm sound support/IEEE floats
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On Sat, 23 Jan 1999, Richard W.E. Furse wrote:

> 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
> 

I'm still not 100% convinced.  I see that floats have an advantage to be
able to represent a signal of a very low DB, and also at a high DB.  The
dynamic range is huge. But how useful is this really for real world
applications?  I mean if a real signal used even a 1/100 of the
dynamic range of a signal, the low end would be inaudible, and the high
end would blast your ears out. It seems to me a waste of bits.

So lets comapare IEEE 32 bit floating point with 32 bit ints for a second.
It seems to me, as far as dynamic range goes, a 32 bit int would be
equivalent to a float with a 24 bit mantissa with a 3 bit exponent.  ( 2 ^
3 = 8)  Do you not think that the 3 bit exponent would provide enough
dynamic range to accomplish the things you outlined in that first message?
I think it would.

If you do think that, then it follows that the 32 bit int can accomplish
those things, plus it has the advantage of an extra 8 bits resolution.

So I guess my point is... Does the 8 bit exponent really provide a
useful advantage?

-Chris








