Subject: Re: [linux-audio-user] virtual sampler
From: Juan Linietsky (coding_AT_reduz.com.ar)
Date: Thu Mar 21 2002 - 22:42:00 EET
On Thu, 21 Mar 2002 21:00:54 +0100
Robert Jonsson <robert.jonsson_AT_dataductus.se> wrote:
> Hi,
>
> >
> > yes, fixed point is quicker. but it makes everything more of a pain to program. suddenly you have to be _very_ careful about overflows on signals etc... :-/ unless someone can tell me it really isnt much of problem - if it isnt then it's something i'd like to do..
> > btw, does anyone know what the (shudder) VST soft-synths use? fixed or floating point?
>
> All VST interfaces are float, I'd guess very few(none) of the synths use
> anything but floats internally.
> It seems to me, in general, that floats should be used always. There are some
> special cases, like audiosystems for hand-computers (which lack fpu) where you
> have to use integer math to achieve any kind of speed.
>
Actually, I think floats offer less precision than fixed point math.
if you think about it, a float has only 23 bits for a real value while
fixed point uses the full 32 ones. This is because the kind of increment range (1/frequency) is known and can be easily controlled (unlike other applications where fixed point can be really annoying) . Natively, the fpu is also slower than than working with integer math. And this is in any architecture that i can think of. MMX helps a lot for moving the data around and calculating in 64bits without the worry of some overflow.
And with the upcoming of 64bits systems, i see using fixed point even more worth it.
Juan Linietsky
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