Scheduling ramp parameters
Scheduling ramp parameters
- Subject: Scheduling ramp parameters
- From: Bjorn Roche <email@hidden>
- Date: Tue, 11 Jul 2006 16:36:32 -0400 (EDT)
Hey all,
I have an AU host app that works fine with non-ramp-able
parameters. However, I recently tried my first plug-in that actually
supports ramp-able parameters, Audio Ease's Altiverb 5 (anybody know any
more?). When I try scheduling parameters with that, it either ignores the
transition or produces a loud noise. In Ableton Live it works fine. I have
two suspicions about why this might be:
1. Instead of lumping all my scheduling together and making one call to
AudioUnitScheduleParameters(), I am making a number of calls with only one
AudioUnitParameterEvent per call, like this:
AudioUnitScheduleParameters( audioUnit, &ape, 1 );
I know this is inefficient, but I understood it to not be wrong. Is it? I
plan to go back later and clean that up, but for now it makes my code much
more straightforward.
2. I am scheduling the parameters right before my own render call, rather
than in the pre-render notification. It has been suggested on this list
that the best place to schedule parameters is in the prerender
notification, but I don't see how it could be an issue as long as I do it
right before the render and from within the same thread. My code does
something like this:
loop while there are more events to schedule:
setup scheduling stuff for one audio unit parameter event
AudioUnitScheduleParameters( audioUnit, &ape, 1 );
AudioUnitRender( audioUnit,
&ioActionFlags,
&timeStamp,
0,
chunksize,
audioBufferList );
that should be fine, too, right? I am, after all, in the same thread and
there's no chance of a render going on while I am scheduling. I am not
relying on an AUGraph or anything like that. I shouldn't really NEED to
create a separate function for pre-render notifications, but is it
possible that an Audio Unit might not work correctly without the
scheduling happening there?
Thanks for the help,
bjorn
-------------
Bjorn Roche
Check out my CD Mastering Software
for Mac OS X : http://www.xowave.com
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