MIDI code will control volume via MIDI events thus the generated audio should
not be affected by mixer sound volumes.
The initial commit 0e6cdfd67580f75e912c5e92abb26821d032f74b added it as music
sound type. Might be copied from the (also) incorrect FluidSynth code.
Based on the SONiVOX® Embedded Audio Synthesis (EAS™) library, which is
part of the base Android OS.
CPU stats (Cortex A8 1GHz, monkey1 intro, peak values):
MAME OPL: 30%
DosBox OPL: 26%
EAS: 19%