Creating Random sample/hold CC

Hi espiegel123 ,

Yeah, I figured you might want this!

To iterate more than 128 times you would nest two loop blocks and get 16k iterations, but for what you want, you probably want to use the SND with a +I flag (Inject) which is a little convoluted but incredibly handy. Here is how it works:

When you specify a +I flag to a SND rule, the event does not get forwarded out of the module's output (and on to the next connected module(s)) but gets injected into the MidiFire routing engine as if it had been received on the input port that caused the SND to issue (or if SND +I is inside an IF/LOAD then falls back to the 'MidiFire' virtual port).

Let's say you have an external controller connected to a Stream Byter and you want to start a loop when you press note C3 and stop it when you release that note:

# setup
IF LOAD
  # constant - loopback event
  ASS K0 = BF 35 7F
  # variable - flag if we are looping
  ASS L0 = 0
END

# handle loop trigger on/off events
9X XX 00 = 8X # convert note on/vel0 to note off
IF M0 == 90 3C
  # got our trigger note on, start looping
  # by sending an internal loop trigger event
  # that we will receive back in 100ms
  SND K0 K1 K2 +I +D100

  # mark as looping
  ASS L0 = 1
END
IF M0 == 80 3C
  # got our trigger note off
  # mark as no longer looping
  ASS L0 = 0
END

# handle internal loopback event
IF M0 == K0 K1 K2
  # we got our trigger event, so
  # here is where you do your stuff
  # in the loop body
  ... your code

  # if we are still looping,
  # send another loopback event
  # to do it all again in 100ms
  IF L0 == 1
    SND K0 K1 K2 +I +D100
  END

  # the loopback event is internal
  # so we should never send it out
  XX = XX +B
END

When you hold down that note, your loop body will get called indefinitely in 100ms intervals until you release the note and then it should stop.

The trigger event doesn't have to be a note - could be a CC on/off - you just change the logic to match your trigger on and trigger off events. If you want to block the trigger event from being sent on out of the Stream Byter then add XX = XX +B in the trigger on/off logic blocks. Obviously you can change the trigger interval from 100ms to whatever suits.

As usual, I just typed in the above. There may be compile/logic errors - it's the method that counts.

Finally, beware while writing this type of stuff since it does create infinite (and undetectable) loops that you don't hang the app by having no delay on the SND +I and no way to stop looping!

This is a MidiFire trick - you cannot do this in the AUv3 or Midi Designer Stream Byter (just in case someone comes across this thread in that context)

Regards, Nic.