Mark.Fong@f444.n161.z1.FIDONET.ORG (Mark Fong) (01/29/91)
How do you mix sounds "on-the-fly" (i.e. if one sound is playing
asynchronously currently, another free-form sound can be mixed in together
without cutting off the first sound.)? I've tried a method using VBL tasks
and actually succeeded, but it was too slow for my SE. I've seen some games
do it quickly, does anyone know how?
Thanks,
Mark Fong
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INTERNET: Mark.Fong@f444.n161.z1.FIDONET.ORGorpheus@reed.UUCP (P. Hawthorne) (01/30/91)
It seems that in order to play multiple, asynchronous sounds, you add the sounds, divide by two, then play the result. Sonic algebra? Sounds like a good band, or at least a good approach. Anyway, it took me a long time to get the Sound Manager working at all, much less well, and I was wondering if there is any code out there that does this already. Anything but reading the Sound Manager docs again! I understand that System 6.07 does this, but I decided not to run that release based on some highly trusted advice. orpheus@reed
ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University) (01/31/91)
Just a note that if you're feeding sound samples direct to the standard Mac sound output hardware, it expects the numbers to be in what I would call "excess-128" form, rather than twos-complement form. To convert one to the other is quite simple: just flip the top bit of the byte (exclusive-or with 128). So if you want to do your own mixing on sound data, you have to convert the data to twos-complement form, do the addition and shifting, and then convert it back. As for dynamic mixing in 6.0.7, that only works on machines with the Apple Sound Chip. Based on my initial *tentative* experiments, I'd say that members of the Mac II family (including the LC) can manage 4 channels max. The Portable, even though it has the ASC, can only manage one. Lawrence D'Oliveiro fone: +64-71-562-889 Computer Services Dept fax: +64-71-384-066 University of Waikato electric mail: ldo@waikato.ac.nz Hamilton, New Zealand 37^ 47' 26" S, 175^ 19' 7" E, GMT+13:00