Apple

On 17 Jun 2010, at 20:33, William Stewart wrote:

On Jun 17, 2010, at 4:27 AM, Luke Hollingworth wrote:

Hi all,

I built a plug-in which is designed to control a remote wave field synthesis (wfs) system. Each instance of the plugin controls a source at the wfs system and the audio on the track played back by the host (usually Logic) is routed out to the wfs system. The plugin has a custom Carbon view which incorporates an xy panel for controlling source position. The problem I have is that when writing automation data for 2 parameters simultaneously the mouse up notifications to the host for the second parameter do not take effect. This is the case for Logic but I have not tried it with other hosts. I found a workaround which is to send a begin parameter change gesture notification before sending the end parameter change notification like so,

const CAAUParameter param(GetComponentInstance(), parameterIndex, kAudioUnitScope_Global, 0);
AudioUnitEvent auEvent;
auEvent.mArgument.mParameter = param;
if (mousedown) {
auEvent.mEventType = kAudioUnitEvent_BeginParameterChangeGesture;
AUEventListenerNotify(m_ParameterListenerOnAU, this, &auEvent);
} else {
auEvent.mEventType = kAudioUnitEvent_BeginParameterChangeGesture;
AUEventListenerNotify(m_ParameterListenerOnAU, this, &auEvent);
auEvent.mEventType = kAudioUnitEvent_EndParameterChangeGesture;
AUEventListenerNotify(m_ParameterListenerOnAU, this, &auEvent);
}

Is there a more correct way of performing this as I would like the code to stay effective in future releases of the SDK.

In the mousedown case you are only notifying of a change to one parameter.

In the mouse up case, you do a begin and end change. So, I don't know how this would work with this code at all.

(the basic MO here is:

for each parameter a gesture can change
begin param event
while (param is changing)
AUParameterSet
end param event

You could test this with the FilterDemo code we provide, that UI allows you to change the two parameters with one gesture.

Bill

References:
	>Controlling multiple parameters with one custom control (From: Luke Hollingworth <email@hidden>)
	>Re: Controlling multiple parameters with one custom control (From: William Stewart <email@hidden>)