How can I modulate midi CC number

There are plenty in ReaPack. e.g. Midi CC Mapper, and Midi Convert To CC -Michael

What exactly is your problem ? That the CC number can't be exactly defined by the envelope curve ? If you can use a Midi item you can use another CC# and have the values of same routed to the "CC#"parameter by [Param] ... Midi link. If you really want to use an envelope curve, you can use Slider to Midi CC additionally converting the envelope to a Midi CC value, and then two instances of Midi Convert To CC with the first narrowing the range of the modulation. Here an example FX chain: Code:

If I understand correctly, I would use a JS FX to convert MIDI PC messages with different data values into numbered CC messages: // converts Program Change messages on the selected MIDI channel // to CC messages on the selected channel, for weird preset selection // the CC number is taken from the PC number

pizmidi midiConverter3 can do this already.