[Stk] Ramping with ADSR

[Ariel Elkin]

…so the class was already there… guess I wasn't even able to reinvent the wheel  :-(

Anyway, so I'm now using Envelope, but the values are still ramping up too slowly. 

This is how I set up my Envelope:

    audioData.envelope = new Envelope();
    audioData.envelope->setTime(10);

And later on I call:

    audioData.envelope->setTarget(400);

But I'm getting the same problem. When I call envelope->lastOut() every 500ms to check its value, after 10 seconds of calling setTarget(), the value is still at around 1.4 instead of 400.

If I divide by 100 the parameter I give to setTime(), then it ramps at more or less the desired duration. Are you sure the value is in seconds?

Ariel


On 17 Sep 2012, at 3:46pm, Gary Scavone wrote:

> If you want a basic ramp, try Envelope (https://ccrma.stanford.edu/software/stk/classstk_1_1Envelope.html).
> 
> --gary
> 
> On 2012-09-17, at 10:39 AM, Ariel Elkin <arielelkin at gmail.com> wrote:
> 
>> Hi all,
>> 
>> I would like to have a sine wave's frequency smoothly go from 0 to 400 over 10 seconds. 
>> 
>> I've tried implementing that with a function that updates the wave's frequency every 20 milliseconds, but there are audible bumps in the sound. So I need something that can create a smoother ramp, and I thought of ADSR. 
>> 
>> But I noticed that calling ADSR::keyOn() automatically sets the attack target to 1.0, and I want it to be an arbitrary value (400.0 in my case). So I added the function below to ADSR:
>> 
>>   void ADSR:: keyTo( StkFloat target )
>>   {
>>       target_ = target;
>>       state_ = ATTACK;
>>   }
>> 
>> Here's how I setup my ADSR object: 
>> 
>>   audioData.adsr = new ADSR();
>>   audioData.adsr->setValue(0);
>> 
>>   audioData.adsr->setAttackTime(10);
>>   audioData.adsr->setDecayTime(1);
>>   audioData.adsr->setReleaseTime(1);
>> 
>> I've then been calling ADSR::lastOut() every 500ms to check its value, and I notice that it goes from 0.0 to about 1.5 in the first 10 seconds. Can anybody see why? Is it possible/a good idea to implement a ramp with ADSR? 
>> 
>> Cheers
>> 
>> Ariel
>> 
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>