Trying to use the true MT-32 feature of ScummVM 1.4.1 on a PowerMac G5 running Mac OS X 10.5.8 with a Roland UM-ONE USB MIDI interface connected to a Roland MT-100 (which is a Roland MT-32 with a QD drive).
The ScummVM configuration is set to output music data to CoreMIDI and the true MT-32 option is selected.
The Activity Monitor utility indicates that MIDIServer is running when ScummVM playing a game configured with the true MT-32 setting on, but the UM-ONE interface is not outputting any data at all to the MT-100. No matter what game I try, there is no MIDI output on the interface.
The interface has had the correct driver from Roland installed. Audio MIDI Setup utility indicates that the UM-ONE is present and I can confirm that the USB MIDI interface is working as I can send MIDI data to the MT-100 through the setup utility. As the settings on ScummVM are correct and the USB MIDI driver properly installed, the problem may be with ScummVM and how it works with CoreMIDI version 1.6 under OS X Leopard.
To further confirm a potential bug with ScummVM with a legacy OS, ScummVM version 1.4.1 on a MacBook Pro running OS X Lion 10.7.4 (CoreMIDI version 1.8) with the same USB MIDI interface and the same MT-100 with ScummVM having the same exact settings as that of the installation on my PowerMac G5 functions perfectly.