dplatt@coherent.com (Dave Platt) (01/06/89)
The problem: I want to use the Sound Manager in my Mac II to generate
some audio test signals. I'll need to generate a sine-wave signal of
arbitrary frequency and amplitude in the left audio channel, and another
one in the right audio channel. Ideally, I'd like to be able to
generate two signals in each audio channel, and be able to alter the
characteristics of each of the four signals in real-time without causing
unpleasant artifacts (clicks or glitches).
The Sound Manager chapter of IM V is woefully lacking in detail as to
how this can be accomplished (or, so it seems to me upon reading the
chapter). It appears that I should set up a simple sine-wave wavetable,
open a pair of sound channels (or, perhaps, four of them?), initialize
the wave-table synthesizer for each channel, and feed in commands to set
the amplitude and frequency for each channels, and then start each
channel with a phase command. It appears that I should be able to
change the amplitude and frequency of each channel independently "on the
fly" (without causing clicks) by sending new amplitude and frequency
commands down the channels.
What I can't figure out is, how to apportion four independent Sound
Manager channels (all running different instances of the wave-table
synth) to the two audio channels. One of the parameters to the "init"
command seems to be the right way to do this... but I can't figure out
what values to use. There are such values as "left stereo channel",
"right stereo channel", "wave-table 1 (2, 3, or 4)", "monophonic
channel", and "stereo channel" (the relationship of which to the "left"
and "right" channels isn't made clear).
Can anybody tell me how to do what I want to do? Is it truly possible
to have two separate wave-table syntheses running at once on the left
audio channel, and another two running on the right? If so, how do I do
it?
Sample code for the Sound Manager, of any sort, would be very much
appreciated!
advTHANKSance...
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USNAIL: Coherent Thought Inc. 3350 West Bayshore #205 Palo Alto CA 94303oster@dewey.soe.berkeley.edu (David Phillip Oster) (01/06/89)
Apple just released a 3-hole punched, revised sound manager chapter to replace the one in Inside Mac Vol.5. The new one apologizes for the old one, and really is much better. Mine came in my December Tech Notes. You can probably order one of your own from APDA.