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Re: ramp parameter of output au
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Re: ramp parameter of output au


  • Subject: Re: ramp parameter of output au
  • From: William Stewart <email@hidden>
  • Date: Thu, 5 Jan 2006 16:33:50 -0800

I'd be interested in seeing the crash log (can you file it at bugreporter.apple.com with some code to reproduce this)

Basically scheduling ramp parameters is a little more complicated than this - you have to schedule the ramp from the same thread you render from (ideally, from the pre-render notification). You have to re-schedule the ramps each render call - so your code progresses through the ramp (the start buffer offset is how you note the progression).

Have a look in the AU docs - /Developer/Examples/CoreAudio/ Documentation for more details on how to do this.

Bill

On 05/01/2006, at 3:28 PM, thomas rettich wrote:

hi,

I am using the default output AU and I want to ramp the kHALOutputParam_Volume from 0.0 to 1.0. and I want this ramp to last for 100000 frames.
the following code causes a segmentation fault. can anybody tell me what I am doing wrong:


struct AudioUnitParameterEvent paramEvent;
	paramEvent.scope= kAudioUnitScope_Global;
	paramEvent.element=0;
	paramEvent.parameter= kHALOutputParam_Volume;
	paramEvent.eventType=kParameterEvent_Ramped;
	paramEvent.eventValues.ramp.startBufferOffset=0;
   paramEvent.eventValues.ramp.durationInFrames= 44000;
   paramEvent.eventValues.ramp.startValue = 0.0;
   paramEvent.eventValues.ramp.endValue= 1.0;

AudioUnitScheduleParameters(
outputAU,
&paramEvent,
0); // i am not sure what value to pass for inNumParamEvents, as I don't know the buf
// size aufileplayer uses



any help would be highly appreciated, thanks, thomas

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References: 
 >ramp parameter of output au (From: "thomas rettich" <email@hidden>)

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