# Bug: MIDI IO with MIDI only plugins in AudioProcessorGraph

**URL:** <https://forum.juce.com/t/bug-midi-io-with-midi-only-plugins-in-audioprocessorgraph/38158>\
**Category:** Audio Plugins\
**Created:** [March 20, 2020, 6:24am UTC](https://forum.juce.com/t/bug-midi-io-with-midi-only-plugins-in-audioprocessorgraph/38158 "2020-03-20T06:24:04Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![mxtommy](https://avatars.discourse-cdn.com/v4/letter/m/e95f7d/32.png) [@mxtommy](https://forum.juce.com/u/mxtommy)\
**Post date:** [March 20, 2020, 6:24am UTC](https://forum.juce.com/t/bug-midi-io-with-midi-only-plugins-in-audioprocessorgraph/38158/1 "2020-03-20T06:24:04Z")

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Hi,

MIDI only plugins (no audio in or out) hosted/patched in row in the AudioProcessorGraph have no MIDI out and can not alter MIDI.

How to reproduce:

Host two MIDI plugins (A & B) in the JUCE TestHost (B needs to be the MIDI only one).  
Route the MIDI out of A in B and the MIDI output of B to the main output.

Scenarios:

- A generates MIDI notes and B clears all its MidiInputMessages: the output of B is the output of A (no messages removed).

- A generates MIDI notes and B adds some more: the output of B is the output of A (no messages added).

B’s MIDI out is simply ignored.

If we add an audio input or output to plugin B everything works as expected and the output of B is a mix of A and B.

Tested with VST3 plugins on Windows.  
But it seems a problem with the graph not with the plugin implementations.

Is this the right place for this report?  
If you need a tester for the fix please let me know. 🙂