denormal floats (was Re: [linux-audio-dev] XAP spec - early scribbles)

[David Olofson]

On Friday 07 February 2003 00.57, Tim Hockin wrote:
> > On Thursday 06 February 2003 16.28, Steve Harris wrote:
> > [...]
> >
> > > #define FLUSH_TO_ZERO(fv) (((*(unsigned
> > > int*)&(fv))&0x7f800000)==0)?0.0f:(fv) I think it came from the
> > > music-dsp list.
> >
> > There's a conditional in there, though.
> >
> > Another method is to add noise or some other signal (beep at
> > Nyqvist) with an amplitude a few hundred dB or more below the 0
> > dB level of audio data.
>
> Which is fine, unless you have a LP filter in your chain.

Yep, but I'm rather thinking about injecting this wherever you need, 
inside plugins. (That's why I was worried about the inner loop 
conditional in the first place.)


> Maybe a -200dB sine at 1Hz and Nyquist?  But then a BP filter
> screws you.

"White" noise is pretty good...


> Someone once suggested a slight DC offset, though I
> can't see how that would solve things like a reverb, unless they
> preserve it and shift their 0.

Right, that only works internally with some algorithms.


//David Olofson - Programmer, Composer, Open Source Advocate

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