fix(musicxml): fix incorrect percussion articulation assignment to notes

packages/alphatab/src/importer/MusicXmlImporter.ts

@@ -97,6 +97,11 @@ class InstrumentArticulationWithPlaybackInfo extends InstrumentArticulation {
      * The balance to use when playing the note (-1 if using the default track balance).
      */
     public outputBalance: number = -1;
+
+    /**
+     * Whether this instrument was declared as an unpitched/percussion sound via `<midi-unpitched>`.
+     */
+    public isUnpitched: boolean = false;
 }
 
 /**
@@ -189,6 +194,10 @@ class TrackInfo {
         this.track.percussionArticulations.push(newArticulation);
         return index;
     }
+
+    public isUnpitchedInstrument(instrumentId: string): boolean {
+        return this.instruments.has(instrumentId) && this.instruments.get(instrumentId)!.isUnpitched;
+    }
 }
 
 /**
@@ -692,6 +701,7 @@ export class MusicXmlImporter extends ScoreImporter {
                     break;
                 case 'midi-unpitched':
                     articulation.outputMidiNumber = Number.parseInt(c.innerText, 10) - 1;
+                    articulation.isUnpitched = true;
                     break;
                 case 'volume':
                     articulation.outputVolume = MusicXmlImporter._interpolatePercent(Number.parseFloat(c.innerText));
@@ -2788,15 +2798,24 @@ export class MusicXmlImporter extends ScoreImporter {
         }
 
         const trackInfo = this._indexToTrackInfo.get(track.index)!;
-        if (instrumentId !== null) {
+
+        if (!isPitched) {
+            // <unpitched> note -> always a percussion/unpitched sound
+            note.percussionArticulation = trackInfo.getOrCreateArticulation(instrumentId ?? '', note);
+            return;
+        }
+
+        // isPitched === true from here on: only treat as percussion if we have
+        // explicit evidence this is really an unpitched/percussion sound. A plain
+        // <instrument> reference on a pitched note can just be disambiguating between
+        // multiple pitched score-instruments in the same part and must not imply percussion.
+        if (instrumentId !== null && trackInfo.isUnpitchedInstrument(instrumentId)) {
             note.percussionArticulation = trackInfo.getOrCreateArticulation(instrumentId, note);
-        } else if (note.beat.voice.bar.staff.isPercussion && isPitched) {
+        } else if (note.beat.voice.bar.staff.isPercussion) {
             const knownArticulation = PercussionMapper.getArticulationById(note.displayValue);
             if (knownArticulation) {
                 note.percussionArticulation = knownArticulation.id;
             }
-        } else if (!isPitched) {
-            note.percussionArticulation = trackInfo.getOrCreateArticulation('', note);
         }
     }
 

packages/alphatab/test-data/musicxml4/percussion-instrument-vs-pitched.xml

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<score-partwise version="4.0">
+    <part-list>
+        <score-part id="P1">
+            <part-name>Mixed</part-name>
+            <score-instrument id="P1-I1">
+                <instrument-name>Piano</instrument-name>
+            </score-instrument>
+            <midi-instrument id="P1-I1">
+                <midi-channel>1</midi-channel>
+                <midi-program>1</midi-program>
+            </midi-instrument>
+            <score-instrument id="P1-I2">
+                <instrument-name>Snare Drum</instrument-name>
+            </score-instrument>
+            <midi-instrument id="P1-I2">
+                <midi-channel>10</midi-channel>
+                <midi-unpitched>38</midi-unpitched>
+            </midi-instrument>
+        </score-part>
+    </part-list>
+    <part id="P1">
+        <measure number="1">
+            <attributes>
+                <divisions>1</divisions>
+                <key>
+                    <fifths>0</fifths>
+                </key>
+                <time>
+                    <beats>4</beats>
+                    <beat-type>4</beat-type>
+                </time>
+                <clef>
+                    <sign>G</sign>
+                    <line>2</line>
+                </clef>
+            </attributes>
+            <note>
+                <pitch>
+                    <step>C</step>
+                    <octave>4</octave>
+                </pitch>
+                <duration>1</duration>
+                <instrument id="P1-I1" />
+                <voice>1</voice>
+                <type>quarter</type>
+            </note>
+            <note>
+                <pitch>
+                    <step>D</step>
+                    <octave>4</octave>
+                </pitch>
+                <duration>1</duration>
+                <instrument id="P1-I2" />
+                <voice>1</voice>
+                <type>quarter</type>
+            </note>
+        </measure>
+    </part>
+</score-partwise>

packages/alphatab/test/importer/MusicXmlImporter.test.ts

@@ -62,6 +62,14 @@ describe('MusicXmlImporterTests', () => {
         expect(score.tracks[0].staves[0].bars[0].voices[0].beats[2].notes[0].isTieDestination).toBe(true);
         expect(score.tracks[0].staves[0].bars[0].voices[0].beats[2].notes[0].tieOrigin).toBeTruthy();
 
+        // notes carry a <instrument id="..."/> reference purely to disambiguate the
+        // score-instrument (a pitched acoustic guitar) - this must not mark them as percussion.
+        for (const beat of score.tracks[0].staves[0].bars[0].voices[0].beats) {
+            for (const note of beat.notes) {
+                expect(note.isPercussion).toBe(false);
+            }
+        }
+
         score = JsonConverter.jsObjectToScore(JsonConverter.scoreToJsObject(score));
 
         expect(score.tracks[0].staves[0].bars[0].voices[0].beats[1].notes[0].isTieOrigin).toBe(true);
@@ -289,6 +297,26 @@ describe('MusicXmlImporterTests', () => {
         expect(notes[1].percussionArticulation).toBe(49);
     });
 
+    it('percussion-instrument-vs-pitched', async () => {
+        const score = await MusicXmlImporterTestHelper.loadFile(
+            'test-data/musicxml4/percussion-instrument-vs-pitched.xml'
+        );
+        const notes = score.tracks[0].staves[0].bars[0].voices[0].beats.flatMap(b => b.notes);
+
+        expect(notes).toHaveLength(2);
+
+        // <pitch> note referencing a normal pitched instrument via <instrument id> just to
+        // disambiguate the score-instrument -> must NOT be treated as percussion.
+        expect(notes[0].isPercussion).toBe(false);
+        expect(Number.isNaN(notes[0].percussionArticulation)).toBe(true);
+        expect(notes[0].realValue).toBe(60); // C4
+
+        // <pitch> note referencing a score-instrument declared unpitched via
+        // <midi-instrument><midi-unpitched> -> IS a genuine percussion sound.
+        expect(notes[1].isPercussion).toBe(true);
+        expect(notes[1].percussionArticulation).toBeGreaterThanOrEqual(0);
+    });
+
     describe('barnumberdisplay', async () => {
         async function testPartwise(filename: string, display: BarNumberDisplay) {
             const score = await MusicXmlImporterTestHelper.loadFile(`test-data/musicxml4/${filename}`);