From:	"Andrew Davidson" <andrew AT lemure DOT freeserve DOT co DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Fast reading of multiple keypresses in Allegro
Date:	Fri, 19 Feb 1999 20:44:14 -0000
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Shawn Hargreaves <ShawnH AT Probe DOT co DOT uk> wrote in message
news:8D53104ECD0CD211AF4000A0C9D60AE356734A AT probe-2 DOT acclaim-euro DOT net...
>Andrew Davidson writes:
>> I think I'm approaching this problem from the wrong angle. Rather
>> than play a sample through allegro's functions is there any way I
>> can simply flex or relax the speakers a single time?
>
>The SB does have a non-DMA mode where you can just write sample
>values to the DAC whenever you feel like it, but I don't think
>this will really do what you want (so what exactly do you want,
>anyway? It would be useful if you could describe your goal in
>a bit more detail :-) Modern soundcards are designed for playing
>streams of sample data at a constant rate, and I think you will
>have a lot of trouble coaxing them to emulate those old speaker
>effects.

I'm actually after emulating the tv speaker connected to a Spectrum computer
which was activated using bit 4 of port 254. The speaker flexes if bit 4 is
a 1 and relaxes if bit 4 is a 0. I need to do this in real time to tie in
with the rest of the emulation.

>If you want to generate a waveform on the fly, you can use the
>Allegro audio streaming functions, as demonstrated in ex28.c.

Would this be capable of playing real time music and sound effects generated
by flexing/relaxing a speaker at differing frequencies? I'll have to have a
look at this.

Andrew

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