Re: simultaneous parameter changes
Re: simultaneous parameter changes
- Subject: Re: simultaneous parameter changes
- From: William Stewart <email@hidden>
- Date: Tue, 20 Mar 2007 12:59:45 -0700
Its a two step process:
(1) set the parameter on the audio unit
(2) notify any listeners that the parameter value has changed
- listeners can have different granularities for notifications, etc.
So, for a host app to correct set parameters, it can either do:
(1) call AudioUnitSetParameter (declared in AudioUnit/AUComponent.h)
with the new parameter value
(2) call AUEventListenerNotify ( declared in AudioToolbox/
AudioUnitUtilities.h) with the information that it just changed the
value of the specified parameter
or
(1) call AUParameterSet ( declared in AudioToolbox/
AudioUnitUtilities.h) which does (1) and (2) above for you
HTH
Bill
On 19/03/2007, at 11:07 AM, Chad Wagner wrote:
I did some more tests in Live with other plugins, and in other apps
with my plugin, and I'm convinced that you are right (even though I
still don't fully understand the role of the host). I sent a
report to Ableton, we'll see if they do anything with it...
As long as it's not my plugin that's at fault I'm okay with it ;-p
Thanks again for the help.
On Mar 17, 2007, at 8:34 PM, Chad Wagner wrote:
Hi Bill, thanks for the response.
I guess I don't understand enough of how an AU host is supposed to
work. So even though AudioUnitBaseSetParameter gets called twice
(once for each parameter), there's another step that's missing?
There's an opaque step in there so I can't figure out exactly
what's supposed to happen or where it is falling short...
If I break in AudioUnitBaseSetParameter so that the two
"simultaneous" calls actually get some space between them, then
the listener proc is called twice as expected, which is why I
suspected my notification interval was the problem. If this
really is a bug in Live, I'd like to understand the issue a little
better before pursuing it with them, and also be sure it's not
just something I'm doing wrong (which was my first assumption)
On Mar 16, 2007, at 9:50 PM, William Stewart wrote:
AUEventListener doesn't make decisions about parameters being
changed or not - if the caller is telling us that both X and Y
parameter is being changed, you should be receiving notifications
for both - this sounds like a bug in Live - they aren't calling
the event listener, just calling AudioUnitSetParameter - you
should contact them
Bill
On 15/03/2007, at 8:04 AM, Chad Wagner wrote:
Hopefully this is an easy question, but it's been giving me some
problems, so any help would be appreciated.
In my AU's carbon view, I set up an event listener with
AUEventListenerCreate, using a notification interval and
granularity of 0.1 sec. I'm testing it in Ableton Live, which
has a generic 2D control that can be mapped to any 2 parameters
of the AU. When using this, both parameter changes are received
correctly by the AU, but my AUEventListenerProc in the GUI is
only called once for one of the parameters, i.e. if both X and Y
values change, I am only notified of X. (I am notified of Y
only if there was no change in X.) I assume this has to do with
the granularity setting, so I tried reducing that (which isn't
really what I want) and also tried creating a different listener
for each parameter (though still using the same callback proc),
but still with the same results.
I'd like the notification interval and granularity to stay at
0.1 sec, since I really don't care about changes that come
faster than that, but I do need to track each parameter
independently and be notified of the current values. What is
the correct way to do this?
Thanks,
Chad
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