[LAU] About Algorithms

Erik de Castro Lopo mle+la at mega-nerd.com
Mon Jul 18 07:38:12 UTC 2011


Moshe Werner wrote:

> Dale Powell to me
> 
> > 64bits is double (comes from 32bit computer architecture, so double uses
> > two words per value.)
> >
> > Single generally uses 24bit values and 8bits of exponent.
> > Double uses 53bit values with 11bits of exponent.
> 
> 
> 
> Oh I see. So whats this Pro tools 48bit mixer talk about that goes on in the
> industry?

That 48 bit thing could hark back to Protools when it used the Motorola
56k DSP chips:

    https://secure.wikimedia.org/wikipedia/en/wiki/Motorola_56000

which are fixed point DPS chips.

According to this:

   https://secure.wikimedia.org/wikipedia/en/wiki/Protools

Protools uses 48 bit fixed point arithmetic (possibly doubled 24 bit
registers of the Moto 56k or possibly custom hardware).

> Why would it be better or more precise than the Ardour mixer (which i prefer
> over Protools).

If it is 48 bit fixed point I would think that it is inferior to
Ardour which almost certain uses double floating point which has
a 53 bit significand.

Erik
-- 
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Erik de Castro Lopo
http://www.mega-nerd.com/


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