feat: add audio chord detection for spectrogram regions

src/util/audioChordDetection.ts

@@ -0,0 +1,55 @@
+import { KGProject } from '../core/KGProject';
+import { KGAudioRegion } from '../core/region/KGAudioRegion';
+import { beatRangeToSeconds, getAudioRegionDisplayLengthBeats } from './globalTrackUtil';
+
+export {
+  detectChordsFromAudio,
+  type AudioChordDetectionRequest,
+  type AudioChordWindow,
+  type DetectedAudioChord,
+} from './audioChordDetectionCore';
+
+import type { AudioChordWindow } from './audioChordDetectionCore';
+
+export function buildAudioChordWindowsForRegion(
+  project: KGProject,
+  audioRegion: KGAudioRegion,
+): AudioChordWindow[] {
+  const regionStartBeat = audioRegion.getStartFromBeat();
+  const visibleLengthBeats = getAudioRegionDisplayLengthBeats(project, audioRegion);
+  if (visibleLengthBeats <= 0) {
+    return [];
+  }
+
+  const regionEndBeat = regionStartBeat + visibleLengthBeats;
+  const beatsPerBar = project.getTimeSignature().numerator;
+  const startBarIndex = Math.floor(regionStartBeat / beatsPerBar);
+  const lastBeatExclusive = regionEndBeat - 1e-9;
+  const endBarIndexExclusive = Math.max(
+    startBarIndex + 1,
+    Math.ceil(Math.max(regionStartBeat, lastBeatExclusive) / beatsPerBar),
+  );
+
+  const windows: AudioChordWindow[] = [];
+  for (let barIndex = startBarIndex; barIndex < endBarIndexExclusive; barIndex++) {
+    const barStartBeat = barIndex * beatsPerBar;
+    const barEndBeat = barStartBeat + beatsPerBar;
+    const overlapStartBeat = Math.max(regionStartBeat, barStartBeat);
+    const overlapEndBeat = Math.min(regionEndBeat, barEndBeat);
+    if (overlapEndBeat <= overlapStartBeat) {
+      continue;
+    }
+
+    const startSeconds = audioRegion.getClipStartOffsetSeconds() + beatRangeToSeconds(project, regionStartBeat, overlapStartBeat);
+    const endSeconds = audioRegion.getClipStartOffsetSeconds() + beatRangeToSeconds(project, regionStartBeat, overlapEndBeat);
+    windows.push({
+      barIndex,
+      startBeat: overlapStartBeat,
+      endBeat: overlapEndBeat,
+      startSeconds,
+      endSeconds,
+    });
+  }
+
+  return windows;
+}