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toSoundingPitch() transposes key signatures by the MIDI program's instrument instead of the part's `<transpose>`

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Valutazione

Difficoltà
3/5
Tempo stimato
Mezza giornata
Idoneità per principianti
62/100
Tipo di issue
Bug
Chiarezza
Specificata chiaramente
Stato di attività
Attiva
Stack tecnologico
python
Ambito
data

Direzione di ricerca

Start by running the reproduction script in the issue: it parses a MusicXML clarinet-in-A part with and without <midi-program> 72 and calls toSoundingPitch(). The note comes out right, but the key signature only goes wrong when the program is 72, so the bug is in how the importer assigns a Clarinet instrument and how its default transposition is applied to the key. Done means the sounding key has 3 sharps in both cases, matching A major, and the <transpose> value is used consistently.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

music21 version

10.5.0

Problem summary

For a clarinet in A written in C, toSoundingPitch() moves the notes down a minor third, following the part's <transpose>, but it moves the key signature down a major second. When the part's <midi-program> is 72 (clarinet), the importer makes the part's instrument a Clarinet, whose default transposition is that of a B♭ clarinet, and the key signature follows that instead. So the sounding notes are in A major, but the sounding key signature is G major.

Steps to reproduce

from music21 import converter, key

def clarinet_in_a(midi_program):
    midi = f'<midi-instrument id="P1-I1"><midi-program>{midi_program}</midi-program></midi-instrument>' if midi_program else ''
    return f'''<score-partwise version="4.0">
  <part-list><score-part id="P1"><part-name>Clarinet in A</part-name>
    <score-instrument id="P1-I1"><instrument-name>Clarinet</instrument-name></score-instrument>{midi}
  </score-part></part-list>
  <part id="P1"><measure number="1">
    <attributes>
      <divisions>1</divisions>
      <key><fifths>0</fifths></key>
      <transpose><diatonic>-2</diatonic><chromatic>-3</chromatic></transpose>
    </attributes>
    <note><pitch><step>C</step><octave>5</octave></pitch><duration>4</duration><type>whole</type></note>
  </measure></part>
</score-partwise>'''

for midi_program in (72, None):
    sounding = converter.parse(clarinet_in_a(midi_program), format='musicxml').toSoundingPitch()
    print(midi_program,
          sounding.flatten().notes[0].nameWithOctave,
          [k.sharps for k in sounding.flatten().getElementsByClass(key.KeySignature)],
          sounding.parts[0].getInstrument().transposition.directedName)

Expected vs. actual behavior

Expected the note A4 and a key signature with 3 sharps both times. Actual:

72 A4 [1] M-2
None A4 [3] m-3

Without the <midi-program>, the part's instrument takes its transposition from <transpose> (minor third down), and the key signature is correct. With program 72, the importer makes a Clarinet with the B♭ clarinet's default transposition (major second down), and that seems to take priority over <transpose> for the key signature, though not for the notes.

Lingua principale
Python
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