PercussionMapper provides tools to convert between MIDI notes and music21 instruments, based on the official General MIDI Level 1 Percussion Key Map. This mapping is conventionally applied to MIDI channel 10; see http://www.midi.org/techspecs/gm1sound.php for more info.
Give me the instrument that corresponds to MIDI note 58!
>>> pm = midi.percussion.PercussionMapper() >>> pm.reverseInstrumentMapping <class 'music21.instrument.Vibraslap'>
That’s right, vibraslap.
But you’re better off using the midiPitchToInstrument() method below!
Takes an instrument.Instrument object and returns a pitch object with the corresponding MIDI note, according to the GM Percussion Map.
>>> pm = midi.percussion.PercussionMapper() >>> myCow = instrument.Cowbell() >>> cowPitch = pm.midiInstrumentToPitch(myCow) >>> cowPitch.midi 56
Note that cowPitch is an actual pitch.Pitch object even though it’s meaningless!
>>> cowPitch <music21.pitch.Pitch G#3>
If the instrument does not have an equivalent in the GM Percussion Map, return an Exception:
>>> myBagpipes = instrument.Bagpipes() >>> pipePitch = pm.midiInstrumentToPitch(myBagpipes) Traceback (most recent call last): music21.midi.percussion.MIDIPercussionException: <music21.instrument.Bagpipes Bagpipes> is not in the GM Percussion Map!
Takes a pitch.Pitch object or int and returns the corresponding instrument in the GM Percussion Map.
>>> pm = midi.percussion.PercussionMapper() >>> cowPitch = pitch.Pitch(56) >>> cowbell = pm.midiPitchToInstrument(cowPitch) >>> cowbell <music21.instrument.Cowbell Cowbell>
Or it can just take an integer (representing MIDI note) for the pitch instead...
>>> moreCowbell = pm.midiPitchToInstrument(56) >>> moreCowbell <music21.instrument.Cowbell Cowbell>
The standard GM Percussion list goes from 35 to 81; pitches outside this range raise an exception.
>>> bassDrum1Pitch = pitch.Pitch('B-1') >>> pm.midiPitchToInstrument(bassDrum1Pitch) Traceback (most recent call last): music21.midi.percussion.MIDIPercussionException: 34 doesn't map to a valid instrument!
Also, certain GM instruments do not have corresponding music21 instruments, so at present they also raise an exception.
>>> cabasaPitch = 69 >>> pm.midiPitchToInstrument(cabasaPitch) Traceback (most recent call last): music21.midi.percussion.MIDIPercussionException: 69 doesn't map to a valid instrument!
Some music21 Instruments have more than one MidiPitch. In this case you’ll get the same Instrument object but with a different modifier
>>> acousticBassDrumPitch = pitch.Pitch(35) >>> acousticBDInstrument = pm.midiPitchToInstrument(acousticBassDrumPitch) >>> acousticBDInstrument <music21.instrument.BassDrum Bass Drum> >>> acousticBDInstrument.modifier 'acoustic'
>>> oneBassDrumPitch = pitch.Pitch(36) >>> oneBDInstrument = pm.midiPitchToInstrument(oneBassDrumPitch) >>> oneBDInstrument <music21.instrument.BassDrum Bass Drum> >>> oneBDInstrument.modifier '1'