Sending midi CCs in VST3

SDK for VST 3 audio plug-in and host development.
olilarkin
Posts: 19
Joined: Tue Jun 21, 2016 11:49 am

Sending midi CCs in VST3

Postby olilarkin » Mon Jun 18, 2018 9:55 am

Is it possible for a plug-in to output midi CC data in VST3?

bx_joscha
Posts: 44
Joined: Thu Aug 24, 2017 6:21 am

Re: Sending midi CCs in VST3

Postby bx_joscha » Mon Jun 18, 2018 11:37 am

Basically, this is not possible, because Control Change events are not directly passed to the plug-in. So, the plug-in cannot directly know if a Control Change event happened and which control has been modified. But there is a workaround: You can create 128 "hidden" parameters and override IMidiMapping::getMidiControllerAssignment(). There you can force the host to map each of the 128 MIDI controllers to a parameter. As soon as the host calls IEditController::setParamNormalized() you can override that callback function in order to react to a modification of a MIDI controller.

Arne Scheffler
Posts: 205
Joined: Mon Jun 20, 2016 7:53 am

Re: Sending midi CCs in VST3

Postby Arne Scheffler » Mon Jun 18, 2018 1:22 pm

Hi Oli,
what's your use case ?

Cheers,
Arne

olilarkin
Posts: 19
Joined: Tue Jun 21, 2016 11:49 am

Re: Sending midi CCs in VST3

Postby olilarkin » Mon Jun 18, 2018 2:48 pm

bx_joscha - thanks, in this case I'm interested in outputting midi ccs - I took exactly the approach you describe for my plug-in VirtualCZ, with incoming CCs

Arne - Although I know it's not ideal from a resolution perspective, sometimes people like to generate MIDI CC modulation for other devices, or make plug-ins that manipulate CC values. I'm actually doing this for a client (adding the functionality to IPlug). I know you have VST-MA, but that seems to have very little support. Being able to do the equivalent of "Audio Unit MIDI FX" with VST3 would be preferable.

bx_joscha
Posts: 44
Joined: Thu Aug 24, 2017 6:21 am

Re: Sending midi CCs in VST3

Postby bx_joscha » Tue Jun 19, 2018 7:44 am

Sorry, Oli, now I understand that you want the plugin to generate MIDI Control Change events and output them to the DAW. I guess this is completely impossible, isn't it Steinberg? But this is an interesting question, indeed.

Arne Scheffler
Posts: 205
Joined: Mon Jun 20, 2016 7:53 am

Re: Sending midi CCs in VST3

Postby Arne Scheffler » Mon Jun 25, 2018 8:59 am

Hi,
I think you can just make a parameter and change its value in the process method and the host should be able to use this as VC source. At least every modular host should be able to do this. You can also use the midi mapping interface to set a default midi CC value for that parameter. So a host is free to generate MIDI CC for external devices.

Cheers,
Arne


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