[chuck-users] ADSR AttackRate, decayRate, sustainRate

[herman verbaeten]

Hi Mario,

Thanks a lot for your answer. Your script is not so easy to read for me and to imagine what is supposed to happen. I run it and it did exactely the same.
Is it correct to say that when i use only attackRate, decayRate, releaseRate it will create a negative envelope. I mean that instead of rising from 0 to the maximum volume attackRate  descents from 0 to a negative volume?


Kind regards,

herman

________________________________
Van: chuck-users-bounces at lists.cs.princeton.edu <chuck-users-bounces at lists.cs.princeton.edu> namens Mario Buoninfante <mario.buoninfante at gmail.com>
Verzonden: dinsdag 18 februari 2020 9:18
Aan: ChucK Users Mailing List <chuck-users at lists.cs.princeton.edu>
Onderwerp: Re: [chuck-users] ADSR AttackRate, decayRate, sustainRate

Hi Herman,

These functions (attackRate, decayRate, releaseRate) are the inverse of the time ones (attackTime, decayTime and releaseTime).
Looking at the source code you'll find the methods at row 4911 of ugen_stk.cpp.
You can try the following script to see them in action:

Step step => ADSR a1 => blackhole;
step => ADSR a2 => blackhole;
step.next(1);

second / samp => float SR;
250::ms => dur attack;
750::ms => dur decay;
0.34 => float sustain;
890::ms => dur release;

a1.set(attack, decay, sustain, release);
a2.attackRate(1::ms / (attack*SR*0.001));
a2.decayRate( (1 - sustain) / ((decay/ms)*SR*0.001) );
a2.sustainLevel(sustain);
a2.releaseRate(sustain / ((release/ms)*SR*0.001));

// trigger the ADSRs and print their current value every 100 msec
a1.keyOn(1);
a2.keyOn(1);
for(0 => int c; c < 20; c++)
{
    <<< a1.last(), a2.last() >>>;
    100::ms => now;
}

// release the ADSRs and print their current value every 100 msec
a1.keyOff(1);
a2.keyOff(1);
for(0 => int c; c < 20; c++)
{
    <<< a1.last(), a2.last() >>>;
    100::ms => now;
}

Cheers,
Mario

On Mon, 17 Feb 2020 at 10:56, herman verbaeten <hverb54 at hotmail.com<mailto:hverb54 at hotmail.com>> wrote:
Hi,

I was wondering what the function is of AttackRate,  decayRate, sustainRate in ADSR.
Normally when using an ADSR,  attack only uses time. Same for decay and sustain.

Also the declaration at the end of de memeber description is not very clear to me:

The \e state = ADSR::DONE after the
    envelope value reaches 0.0 in the
    ADSR::RELEASE state.


Thanks in advance for your assistance.

Kind regards,

Herman
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