Mixing kontrol rate and audio rate in a same UGen

21

Do you mean in this kind of faust2supercollider generate file, that currently only adds control input (gain, freq here) ?


FaustOsc : UGen
{
  *ar { | gain(0.0), freq(1000.0) |
      ^this.multiNew('audio', gain, freq)
  }

  *kr { | gain(0.0), freq(1000.0) |
      ^this.multiNew('control', gain, freq)
  } 

  name { ^"FaustOsc" }


  info { ^"Generated with Faust" }
}
22

Exactly! If you want more than one output, you would typically inherit from MultiOutUGen and call initOutputs in the init method:

init { |numOutputs ... inputs|
    this.inputs = inputs;
    ^this.initOutputs(numOutputs, this.rate);
}

You also need to pass the number of outputs to multiNew (which will forward it to init):

^this.multiNew('audio', numOutputs, <inputs...>);
23

Thanks, but not sure to understand. How is numOutputs computed then ? Do you have a complete example of MultiOutUGen based UGen ?

24

That is totally up to you! As I said, in your case it would be the number of audio outputs + the number of “control” outputs.

Do you have a complete example of MultiOutUGen based UGen ?

A very simple example would be the In UGen. For a more complex example, see VSTPlugin.

25

OK, C++ code updated, output control is written here: faust/architecture/supercollider.cpp at 8715622a78012c1cd385658e7a6d9ee5bb0ec19d · grame-cncm/faust · GitHub

And for a DSP with 0 input, 1 audio output and 1 control output, the generated sc file is now:

FaustOsc : MultiOutUGen
{
  *ar { | gain(0.0), freq(1000.0) |
      ^this.multiNew('audio', gain, freq)
  }

  *kr { | gain(0.0), freq(1000.0) |
      ^this.multiNew('control', gain, freq)
  } 

  init { | ... theInputs |
      inputs = theInputs
      ^this.initOutputs(2, rate)
  }

  name { ^"FaustOsc" }


  info { ^"Generated with Faust" }
}

But the generated audio output is distorted, as soon at the control output is also written, with the OUT0(curControl) = unit->getOutputControl(i)->updateOutput(); or fillBuffer(OUT(curControl), inNumSamples, unit->getOutputControl(i)->updateOutput());

Any idea ?

26

The code itself looks fine. Can you show your code for monitoring the sound? BTW, if you plot the outputs, it’s probably more clear what’s going on.

27

It’s actually working, I was testing incorrectly, thanks for the help :grinning: !

2 Likes
28

You’re right - you can know the block size when you construct the SynthDef in sclang, but when the synthdef file is deserialized from disk it may be in the context of a server with a different block size, so it would no longer be valid. Probably this could be made to work, except cached synthdefs would be invalid if you booted the server with a different block size, which is obviously not good. The alternative here would be to use a LocalBuf I guess - this would give you a fixed size buffer into which you could pack/unpack values.

29

From what I see, mixing audio rate and control rate should be possible after all. I’ll make a PoC.