From: myknees AT aol DOT com (Myknees)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Audio recording and mixing
Date: 12 Feb 1998 02:04:54 GMT
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References: <yqxv+PAShf40Ew9d AT talula DOT demon DOT co DOT uk>
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To: djgpp AT delorie DOT com
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Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk> writes:
> Myknees writes:
> >I read a short tutorial on digital audio mixing that 
> >basically said 
> >that one must program the mixing routines in assembly. 
> >Do you think 
> >that has any truth to it?
> 
> I don't see why. Sample mixing is exactly the same as
> any other
> programming task: you can use whatever language you
> like. The Allegro
> mixing code is regular C.

I am smiling now.

> >Also, I have accidentally caused mixing to occur with 
> >this loop (based on
> >ex17.c):
> >    do {
> >      if (key[KEY_Q]){
> >       play_sample(the_sample, 255, pan, pitch, FALSE);
> >       rest(50);
> >      }
> >      else if(key[KEY_W]){
> >       play_sample(the_sample, 255, pan, pitch*2, FALSE)
> >       FALSE);
> >       rest(50);
> >      }
> >    } while ((!key[KEY_ESC]) && (!key[KEY_SPACE]));
> >
> >It makes reverb.  Where is the mixing occurring?
> 
> I presume you only get the overlapping samples if you
> press the Q and W
> keys in rapid succession? 

No, (sorry I was not clear) I hear reverb since the rest value is only 50ms. 
If I hit Q for, say, a quarter second, I'll hear a rapid succession of five
played samples.  But you go on to answer the question...

> Allegro can mix up to 32
> simultaneous samples
> (the exact number depending on the config file and how
> many voices you
> reserve when setting up the sound module). The code for
> this is in the
> mixer.c file.
>
[snip]
I will go ruminate on the rest of your post.  

--Ed (Myknees)