Issue with MIDI output from plugin

DSP, Plug-in and Host development discussion.
2 posts since 9 Aug, 2018

Post Wed Aug 08, 2018 11:10 pm

Hi, I'm working on a synth plugin (focusing on VST at the moment, but other formats are supported). I need to send MIDI messages to the host, but they seem to be disappearing into the aether after I hand off my event buffer to sendVstEventsToHost.

The VST wrapper is my own, so I imagine that's where the issue is. I've overridden getNumMidiOutputChannels to return 1, and I'm returning 1 in my canDo override for sendVstEvents etc. However, when I try to route the MIDI from the track my synth plugin is on to another track, nothing comes out the other end.

Any suggestions? Threads that I've missed? Secret (or forgotten :ud: ) parameters that I haven't set correctly? Thanks~

2 posts since 9 Aug, 2018

Re: Issue with MIDI output from plugin

Post Thu Aug 09, 2018 8:09 pm

Ok, I finally found a thread with the secret, so I'm posting it here for whatever other poor sucker gets stuck on this. ... iew=unread

So the step by step guide for outputting MIDI to your host from a VST plugin is :

1) Make sure you have your midi output channels set to something greater than 0, and make sure your canDo override is returning 1 for sendVstEvents and the associated options.

2) Not relevant for my case, but it seems like you need to have a non-zero number of audio outputs for many DAWs to run your process/processReplacing properly.

3) Collect your MIDI events in a buffer, and pass them to the host using the API method sendVstEventsToHost *in your process loop*. The VST documentation is vague on this, but it seems like this is the best option.

4) Make sure your routing is correct: I wasted a bunch of time thinking I was coding something wrong because my MIDI out was working in Reaper but not was the routing.

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