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Mail Archives: djgpp/2000/01/29/18:02:37

From: Michael Burian <michael DOT burian AT sbg DOT at>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Realtime Sound
Date: Sat, 29 Jan 2000 23:39:15 +0100
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Gisle wrote:
> 
> Do anyone know how to manipulate sound in realtime
> (treble+bass+effects) --jgmod

this is IMHO quite a kafkaesque thing to do on PC´s without custom made
hardware.
Most soundcard support just DMA at reasonable sampling rates, -depths,
-frequencies,
and setting up 4 byte sized DMA buffers will load your CPU near
breakdown (44100 IRQ´s per second),
If you can live with small delays, (1 milliseconds and below) you can
reduce buffer size from the recomended 4096 bytes down till clicking and
poping occurs, but in general you have to get your feet wet and 
solve the problem on a very low level (Assembler), this mostly leads to
non portable and heavily system dependant programming, and if you have
to do some serious DSP, I´m quite sure you won´t get around buying a DSP
evaluation board. (to save you from learning another low level language
make sure that a free C compiler is included)

this shouldn´t discourage anybody from putting effort into the attempt
of 
doing DSP with PC´s, but as far a I have tried it´s quite a pain to do
the really interesting things in the noise area.

btw: some soundcard are equipped with programable mixers (yes, treble,
bass) but
I´m quite sure that´s nothing new for you, and FX can´t be done that
way.

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