auto-interpolation between points on automation curves

[emf]

Greetings,

 

I'm algorithmically generating MIDI data in SuperCollider and sending it to an instance of Retro Synth in Logic, via the macOS IAC driver. Specifically, I'm generating a looping sequence of CC messages with controller values [10, 20, ... 80].

 

If these messages arrive slowly (ca. every 1/2 second), Logic does not interpolate between them and produces a staircase automation shape. If these messages arrive quickly (ca. every 1/10th of a second), Logic will linearly interpolate between values. And, at some intermediate speeds, Logic will seemingly randomly interpolate, producing a partially staircased automation shape. Screenshot included.

 

Is this behavior explainable? Is there a way to completely disable this interpolation feature so that a non-interpolated staircase is always the result?

 

Thank you!

Eli

[Atlas007]

Have you tried different snap settings, snap offsets, and/or ramp time?

[emf]

Atlas, thank you for the suggestion. I've tried varying these parameters, but I can't produce the desired result. As I understand it, snap settings affect the location of automation points relative to the tempo grid. I'm interested in how Logic determines what happens between these points. Ramp time looks to be relevant only when automation data already exists on a track and new data is being recorded over it.

 

Here is a short video to better document the behavior:

 

 

 

Notice that when I stop recording in Logic, the desired staircase automation shape is produced. However, when I stop the SuperCollider routine responsible for sending MIDI CC messages, there is a half-second pause, and then Logic appears to perform an autonomous "second pass" through the recorded data, interpolating between some (but not all) adjacent automation points (ca. 0:26 in the video).

 

One thought that occurs to me is that the pattern of control data I am sending, e.g. instantaneously "jumping" from a controller value of 10 to a value of 70, is not possible using a physical controller, and so perhaps Logic is attempting to "correct" this unusual/unexpected input data.

 

This is not a "help my project is due in 2 hours" sort of problem -- more of a curiosity than anything else. Any insight is appreciated.

 

Eli

[David Nahmani]

Instead of writing automation, try simply recording the MIDI events Logic is receiving. 

[emf]

Thank you! This certainly sounds like the right idea. A little more guidance would be really helpful. Would I do this with an Instrument track, or with an External MIDI track? And/or does this involve the Event List window?

[David Nahmani]

If somehow in your setup you can use the MIDI CC to trigger the desired parameter, then you don't have to assign the knob to that parameter using Logic's control surface assignments. Once you've made sure that MIDI CC isn't assigned to anything in Logic's control surfaces, you can just record-enable the current instrument track, and record the MIDI CC right on the same track, along with the MIDI notes.

[emf]

Perfect, thank you David! This is very clear. I switched over to FM8 (Komplete), which has a MIDI learn feature built into the plug-in. After assigning the CC values this way, I'm able to record MIDI data exactly as it comes in, circumventing automation.

 

So then, am I correct that the design of an instrument plug-in will determine whether this type of MIDI recording will be possible? Specifically, if a plug-in has no built-in MIDI learn function, are Logic's controller assignments and automation the only option for connecting arbitrary MIDI CC data with arbitrary synth parameters?

 

And for Retro Synth specifically, is there a built-in MIDI learn function? If so, I'm not seeing it.

 

Thanks again for the help -- much appreciated.

 

Eli

[David Nahmani]

am I correct that the design of an instrument plug-in will determine whether this type of MIDI recording will be possible? Specifically, if a plug-in has no built-in MIDI learn function, are Logic's controller assignments and automation the only option for connecting arbitrary MIDI CC data with arbitrary synth parameters?

You're correct, yes, the plug-in needs either a MIDI Learn function or, for software instrument plug-ins, simply the capability to have MIDI controllers directly control some parameters.