DemandEnvGen question

Questions
1

Hello,

I’m trying to learn more about how Demand rate ugens work, specifically DemandEnvGen. I’m used to using regular EnvGen for envelopes to control things like freq or amplitude. In the case of DemandEnvGen, if I don’t give it anything to control, I’m wondering why I still get sound.

I ran across the below example and it generates a buzzy/noisy sound. I’m not clear what’s going on and why it makes the sound it does, and how altering these params might affect the sound? Thanks for any info!

(
{
     DemandEnvGen.ar(
          Dseq([1, [-1, 0.5]], repeats: inf),
          Dseq([7, 9, 12, 25, 15], repeats: inf) * (SampleDur.ir * 0.15)
    ) * 0.1;

}.play
)
2

the DemandEnvGen makes a ramp to the level specified by the first argument in the time specified by the second argument. so the first ramp is from 1 to -1 on the left channel and from 1 to 0.5 on the right. the ramp will take 7 * the duration of 1 sample * 0.15 (about 1 sample!). Once that ramp is done all the Dseqs will be polled again to get the value and time for the next ramp. So for the second ramp we get a value of 1 (for both channels) and a time of 9 * 1 samp * 0.5 or around a sample and a half. and so on.

So the values in the Dseqs define a little waveform! These can be interestingly complex if you fiddle with them.

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3

Ah, thanks so much @semiquaver ! So this is a technique for manually creating an arbitrary waveform then. I’ve just been working with the usual ugen waveforms so far, but am interested in exploring different types of noise and stochastic sound design - any idea where I might look to explore more techniques for this?

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4

You can check chapter 19 of the SuperColler Book, 2nd edition, “Stochastic and Deterministic Algorithms for Sound Synthesis and Composition”, written by Sergio Luque and me. Sergio is the expert in Stochastic Synthesis. There are some examples employing DemandEnvGen, you can find the source code under the last link below.

best

Daniel

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