Re: [LAU] About Algorithms

David Adler wrote:

> On Mon, Jul 18, 2011 at 12:13 PM, Renato wrote:
> > On Mon, 18 Jul 2011 11:53:47 +0200
> ...
> > isn't it useless going way above 24 bits, since that's what in the end
> > the DAC (sound card) will use? as far as I can remember, delta-sigma
> > DACs don't go over 24 bit, do they?
> >
> More than 24 bit for DAC/ADC is useless, going above 24 bit for
> internal processing is not. The latter ensures that rounding errors
> that may be introduced by multiple math operations disappear when bit
> depth is finally reduced again to 24 before entering the DAC.

Do not confuse DAC/ADC bit width with bit widths used during DSP
calculations. The two are basically orthogonal.

> The magnitude of rounding errors depends on the type and number of
> operations done. I don't know the limits, but for what Fons calls
> "normal audio engineering practise" (see his posting above), 32 bit is
> enough.

For audio data paths this is true. For the intermediate results
during complicated calculations (eg filters and reverbs) double
precision makes things easier and is basically available for free.

Erik

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