Support the volume knob, modulation, and pitch bend on MIDI controllers

[probonopd]

Support the volume knob on MIDI controllers.

(Once #8 is implemented I can say which MIDI message the volume knob sends.)

[dcoredump]

Will do this with adding MIDI processing support for Synth_Dexed (see also #10, #11)

[probonopd]

The volume MIDI messages are B0 07 00 (knob all the way left) to B0 07 7F (knob all the way right).

[probonopd]

Likewise, B0 01 ... for modulation and E0 00 ... for Pitch Bend.

[rsta2]

I was so bold and implemented the volume control (using MIDI CC and via the UI) already in #47. ;) I also tried modulation (using Dexed::setModWheel()) and pitch bend (using setPitchbend()), but this didn't work. Or I wasn't able to "move the wheel" quick enough, because I can only simulate the MIDI messages by sending hex bytes manually. I also don't know, if it depends on the loaded voice, if these functions have an effect.

BTW. Pitch bend was already implemented, but I think this MIDI message has two parameter bytes (0xE0 LSB MSB), and the MSB is not considered yet.

[dcoredump]

I was so bold and implemented the volume control (using MIDI CC and via the UI) already in #47. ;) I also tried modulation (using Dexed::setModWheel()) and pitch bend (using setPitchbend()), but this didn't work. Or I wasn't able to "move the wheel" quick enough, because I can only simulate the MIDI messages by sending hex bytes manually. I also don't know, if it depends on the loaded voice, if these functions have an effect.

ModWheel depends on the routing of the voices. Some voices don't have a target for the ModWheel.

BTW. Pitch bend was already implemented, but I think this MIDI message has two parameter bytes (0xE0 LSB MSB), and the MSB is not considered yet.

Yes, Pitchbend is 14 bit (LSB, MSB)!

[probonopd]

E0 00 ... for Pitch Bend

To be precise, E0 00 40 (normal pitch wirthout bending) all the way down to E0 00 00 and all the way up to E0 7F 7F

B0 01 ... for modulation

B0 01 00 to B0 01 7F

[rsta2]

@dcoredump Ah OK, I probably used a voice, which don't use the ModWheel. Thanks for info.

@probonopd This is something, I did wonder about today. When the zero pitch bend level is 0x4000 (I have seen this value too in some doc), then you have to subtract 0x4000 from the value before calling Dexed::setPitchbend(). But inside this function, it adds 0x2000 only to get back to the 0..16383 range. I don't understand this.

https://codeberg.org/dcoredump/Synth_Dexed/src/branch/master/src/dexed.cpp#L866

[probonopd]

Does https://sites.uci.edu/camp2014/2014/04/30/managing-midi-pitchbend-messages/ help?

[rsta2]

@probonopd Yes, this helps. The message 0xE0 0x00 0x40 is the zero level (0x4000). This is the value before shifting the MSB, after shifting it's 0x2000. This is because both value bytes are only 7 bits. Thanks!

[rsta2]

Here is a patch, which should implement Pitch Bend and Modulation CC. Unfortunately I do not have such controls, so I cannot test it.

pitch-bend-modulation.zip

[probonopd]

Thanks @rsta2, unfortunately it does not seem to have any audible effect.
@dcoredump can you reproduce this?

[rsta2]

@probonopd This was also my impression, when trying to fake a Pitch Bend and modulation by sending the MIDI bytes manually with a tool. I tried several voices. But I thought, that you need a real controller to test this.

[dcoredump]

@dcoredump can you reproduce this?

Sorry, but I have no equipment which can send MIDI-CC right here - my master keyboard is in the rehearsal room...

[rsta2]

I was looking around in Synth_Dexed, and now Pitch Bend and Modulation does work (e.g. with the "BRASS 1" voice), when you apply the attached patch to the version from the pb-mod branch. There are two major things to do, that it works:

• The controllers must be configured using Dexed::setPBController (range, step) and Dexed::setMWController (range, assign, mode). Pitch Bend range and step can be from 0 to 12. Modulation Wheel range can be 0 to 99, assign 0 to 7 and mode 0 to 2. Currently I don't know, if these values should be configurable in minidexed.ini or somewhere else?

• Have to call Dexed::ControllersRefresh() after Dexed::setModWheel().

I tested it, by manually sending MIDI bytes, and there was definitely some reaction. But we have to find out more about the different configuration parameters.

pb-mod-2.zip

[probonopd]

Pitch Bend and Modulation now do something audible. In fact, I think they "overreact" a bit (do more than intended).
But this is just a gut feeling at the moment.

I think ideally we should compare with a real DX7 and configure the controllers to do as much (or as little) modulation as the original. Unfortunately I don't have access to one. I wonder how the Dexed VST plugin is configured by default. Maybe we should use that configuration?

[rsta2]

I installed Dexed on Windows. These controllers are switched off by default there. I guess we have to find out a setup by our self here. In the TX802 Manual on page 22 there is the description for the Pitch Bend parameters, on page 23 for Mod wheel.

[probonopd]

Volume knob, modulation, and pitch bend on MIDI controllers are working and tested successfully. In case some further tuning of parameters is needed, we can always open separate tickets.

Thanks @rsta2 for implementing this!