fix: handle GP5 percussion instruments which were removed in later GP versions

packages/alphatab/src/importer/Gp3To5Importer.ts

@@ -54,6 +54,26 @@ import { BeamDirection } from '@coderline/alphatab/rendering/utils/BeamDirection
  */
 export class Gp3To5Importer extends ScoreImporter {
     private static readonly _versionString: string = 'FICHIER GUITAR PRO ';
+
+    // NOTE: General Midi only defines percussion instruments from 35-81
+    // Guitar Pro 5 allowed GS extensions (27-34 and 82-87)
+    // GP7-8 do not have all these definitions anymore, this lookup ensures some fallback 
+    // (even if they are not correct)
+    // we can support this properly in future when we allow custom alphaTex articulation definitions
+    // then we don't need to rely on GP specifics anymore but handle things on export/import
+    private static readonly _gp5PercussionInstrumentMap = new Map<number, number>([
+        // High Q -> GS "High Q / Filter Snap"
+        [27, 42],
+        // Slap
+        [28, 60],
+        // Scratch Push
+        [29, 29],
+        // Scratch Pull
+        [30, 30],
+        // Square Click
+        [32, 31]
+    ]);
+
     private _versionNumber: number = 0;
     private _score!: Score;
     private _globalTripletFeel: TripletFeel = TripletFeel.NoTripletFeel;
@@ -1225,7 +1245,9 @@ export class Gp3To5Importer extends ScoreImporter {
         }
 
         if (bar.staff.isPercussion) {
-            newNote.percussionArticulation = newNote.fret;
+            newNote.percussionArticulation = Gp3To5Importer._gp5PercussionInstrumentMap.has(newNote.fret)
+                ? Gp3To5Importer._gp5PercussionInstrumentMap.get(newNote.fret)!
+                : newNote.fret;
             newNote.string = -1;
             newNote.fret = -1;
         }

packages/alphatab/src/model/PercussionMapper.ts

@@ -1068,7 +1068,8 @@ export class PercussionMapper {
             }
         }
 
-        return 'unknown';
+        // unknown combination, should not happen, fallback to some default value (Snare hit)
+        return 'Snare (hit)';
     }
 
     public static getArticulation(n: Note): InstrumentArticulation | null {

packages/alphatab/test/exporter/AlphaTexExporter.test.ts

@@ -168,6 +168,10 @@ describe('AlphaTexExporterTest', () => {
         await testRoundTripEqual(`conversion/full-song.gp5`);
     });
 
+    it('gp5-articulation', async () => {
+        await testRoundTripEqual(`guitarpro5/percussion-all.gp5`);
+    });
+
     it('gp6-to-alphaTex', async () => {
         await testRoundTripEqual(`conversion/full-song.gpx`);
     });

packages/alphatab/test/importer/Gp5Importer.test.ts

@@ -9,6 +9,7 @@ import { BeamDirection } from '@coderline/alphatab/rendering/utils/BeamDirection
 import { GpImporterTestHelper } from 'test/importer/GpImporterTestHelper';
 import { expect } from 'chai';
 import { Clef } from '@coderline/alphatab/model/Clef';
+import { PercussionMapper } from '@coderline/alphatab/model/PercussionMapper';
 
 describe('Gp5ImporterTest', () => {
     it('score-info', async () => {
@@ -553,4 +554,19 @@ describe('Gp5ImporterTest', () => {
         expect(score.tracks[2].staves[0].bars[0].clef).to.equal(Clef.F4);
         expect(score.tracks[3].staves[0].bars[0].clef).to.equal(Clef.F4);
     });
+
+    it('percusson', async () => {
+        const score = (await GpImporterTestHelper.prepareImporterWithFile('guitarpro5/percussion-all.gp5')).readScore();
+
+        let beat: Beat | null = score.tracks[0].staves[0].bars[0].voices[0].beats[0];
+
+        while (beat) {
+            if (beat.notes.length === 1) {
+                const articulationName = PercussionMapper.getArticulationName(beat.notes[0]);
+                const hasArticulation = PercussionMapper.instrumentArticulationNames.has(articulationName);
+                expect(hasArticulation).to.be.true;
+                beat = beat.nextBeat;
+            }
+        }
+    });
 });