fix: changing BPM in the middle of the song causes empty spaces between notes during playback/bounce

src/core/audio-interface/KGAudioInterface.test.ts

@@ -1,6 +1,8 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
-import { createMockMidiPitchBend, createMockMidiRegion, createMockMidiTrack, createMockProject } from '../../test/utils/mock-data';
+import { createMockMidiNote, createMockMidiPitchBend, createMockMidiRegion, createMockMidiTrack, createMockProject } from '../../test/utils/mock-data';
 import { MockTransport } from '../../test/mocks/tone';
+import { GlobalTrackType } from '../global-track';
+import { KGTempoRegion } from '../region/KGTempoRegion';
 
 vi.mock('tone', async () => {
   const { ToneMock } = await import('../../test/mocks/tone');
@@ -41,6 +43,22 @@ function createMockAudioBus() {
   };
 }
 
+function setTempoRegions(project: ReturnType<typeof createMockProject>, regions: KGTempoRegion[]): void {
+  const tempoTrack = project.getGlobalTracks().find(track => track.getType() === GlobalTrackType.Tempo);
+  if (!tempoTrack) {
+    throw new Error('Tempo track missing in test setup');
+  }
+
+  tempoTrack.setRegions(regions);
+}
+
+function transportTimeToBeats(time: unknown): number {
+  if (typeof time === 'string' && time.endsWith('i')) {
+    return Number.parseFloat(time.slice(0, -1)) / MockTransport.PPQ;
+  }
+  return Number(time);
+}
+
 describe('KGAudioInterface preroll playback', () => {
   beforeEach(() => {
     vi.useFakeTimers();
@@ -53,6 +71,7 @@ describe('KGAudioInterface preroll playback', () => {
     MockTransport.clear.mockClear();
     MockTransport.schedule.mockClear();
     MockTransport.bpm.value = 120;
+    ;(MockTransport as typeof MockTransport & { seconds?: number }).seconds = 0;
 
     const project = createMockProject({
       bpm: 120,
@@ -129,7 +148,7 @@ describe('KGAudioInterface preroll playback', () => {
     const audio = KGAudioInterface.instance();
     audio.preparePlayback(project, 12, { allowStartBeforeLoopStart: true });
 
-    expect(MockTransport.position).toBe(6);
+    expect(MockTransport.position).toBe(0);
   });
 
   it('schedules baked pitch bend points instead of authored step changes only', () => {
@@ -147,9 +166,9 @@ describe('KGAudioInterface preroll playback', () => {
     ;(audio as unknown as { trackAudioBuses: Map<string, unknown> }).trackAudioBuses.set('1', audioBus);
     audio.preparePlayback(project, 0);
 
-    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => time);
-    expect(scheduledTimes).toContain(0.25);
+    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => transportTimeToBeats(time));
     expect(scheduledTimes).toContain(0.5);
+    expect(scheduledTimes).toContain(1);
   });
 
   it('skips redundant scheduled pitch bend events when interpolated values round to the same MIDI value', () => {
@@ -167,8 +186,8 @@ describe('KGAudioInterface preroll playback', () => {
     ;(audio as unknown as { trackAudioBuses: Map<string, unknown> }).trackAudioBuses.set('1', audioBus);
     audio.preparePlayback(project, 0);
 
-    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => time);
-    expect(scheduledTimes).toEqual([0.25]);
+    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => transportTimeToBeats(time));
+    expect(scheduledTimes).toEqual([0.5]);
   });
 
   it('computes the initial interpolated bend for non-zero playback starts', () => {
@@ -207,8 +226,74 @@ describe('KGAudioInterface preroll playback', () => {
     ;(audio as unknown as { trackAudioBuses: Map<string, unknown> }).trackAudioBuses.set('1', audioBus);
     audio.preparePlayback(project, 5);
 
-    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => time);
-    expect(scheduledTimes).toContain(2);
+    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => transportTimeToBeats(time));
+    expect(scheduledTimes).toContain(0);
+  });
+
+  it('schedules post-tempo-change notes using playback-local transport time', () => {
+    const notes = [
+      createMockMidiNote({ id: 'note-1', startBeat: 4, endBeat: 5 }),
+      createMockMidiNote({ id: 'note-2', startBeat: 5, endBeat: 6 }),
+    ];
+    const region = createMockMidiRegion({ notes, length: 8 });
+    const track = createMockMidiTrack({ id: 1, regions: [region] });
+    const project = createMockProject({ bpm: 120, tracks: [track] });
+    setTempoRegions(project, [
+      new KGTempoRegion('tempo-a', 'tempo-track', 0, 120, 0, 1, 4),
+      new KGTempoRegion('tempo-b', 'tempo-track', 0, 60, 1, 31, 4),
+    ]);
+
+    const audio = KGAudioInterface.instance();
+    const audioBus = createMockAudioBus();
+    ;(audio as unknown as { trackAudioBuses: Map<string, unknown> }).trackAudioBuses.set('1', audioBus);
+
+    audio.preparePlayback(project, 0);
+
+    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => transportTimeToBeats(time));
+    expect(scheduledTimes.filter(time => time === 4)).toHaveLength(2);
+    expect(scheduledTimes).toContain(5);
+  });
+
+  it('keeps post-tempo-change note spacing correct for nonzero playback starts', () => {
+    const notes = [
+      createMockMidiNote({ id: 'note-1', startBeat: 4, endBeat: 5 }),
+      createMockMidiNote({ id: 'note-2', startBeat: 5, endBeat: 6 }),
+    ];
+    const region = createMockMidiRegion({ notes, length: 8 });
+    const track = createMockMidiTrack({ id: 1, regions: [region] });
+    const project = createMockProject({ bpm: 120, tracks: [track] });
+    setTempoRegions(project, [
+      new KGTempoRegion('tempo-a', 'tempo-track', 0, 120, 0, 1, 4),
+      new KGTempoRegion('tempo-b', 'tempo-track', 0, 60, 1, 31, 4),
+    ]);
+
+    const audio = KGAudioInterface.instance();
+    const audioBus = createMockAudioBus();
+    ;(audio as unknown as { trackAudioBuses: Map<string, unknown> }).trackAudioBuses.set('1', audioBus);
+
+    audio.preparePlayback(project, 2);
+
+    const scheduledTimes = MockTransport.schedule.mock.calls.map(([, time]) => transportTimeToBeats(time));
+    expect(scheduledTimes.filter(time => time === 2)).toHaveLength(2);
+    expect(scheduledTimes).toContain(3);
+  });
+
+  it('maps transport seconds back to project beats across a tempo change', () => {
+    const project = createMockProject({ bpm: 120, tracks: [] });
+    setTempoRegions(project, [
+      new KGTempoRegion('tempo-a', 'tempo-track', 0, 120, 0, 1, 4),
+      new KGTempoRegion('tempo-b', 'tempo-track', 0, 60, 1, 31, 4),
+    ]);
+
+    vi.mocked(KGCore.instance).mockReturnValue({
+      getCurrentProject: () => project,
+    } as unknown as KGCore);
+
+    const audio = KGAudioInterface.instance();
+    audio.preparePlayback(project, 2);
+    ;(MockTransport as typeof MockTransport & { seconds?: number }).seconds = 2;
+
+    expect(audio.getTransportPosition()).toBeCloseTo(5, 5);
   });
 });
 

src/core/audio-interface/KGAudioInterface.ts

@@ -76,6 +76,8 @@ export class KGAudioInterface {
   private delayedTransportStartSeconds: number = 0;
   private virtualPrerollStartBeat: number | null = null;
   private virtualPrerollStartAudioTime: number | null = null;
+  private playbackOriginBeat: number = 0;
+  private playbackOriginSeconds: number = 0;
 
   // Master volume control
   private masterGain: Tone.Gain | null = null;
@@ -471,21 +473,24 @@ export class KGAudioInterface {
         scheduleStartBeat = startBar * beatsPerBar;
         scheduleEndBeat = (endBar + 1) * beatsPerBar; // +1 because endBar is inclusive
 
-        // Configure Tone.Transport loop boundaries
-        const loopStartTime = this.beatsToToneTime(scheduleStartBeat);
-        const loopEndTime = this.beatsToToneTime(scheduleEndBeat);
-        Tone.Transport.setLoopPoints(loopStartTime, loopEndTime);
-        Tone.Transport.loop = true;
-
-        console.log(`Loop mode enabled: bars [${startBar}, ${endBar}], beats [${scheduleStartBeat}, ${scheduleEndBeat}]`);
-
         // Adjust start position to loop start if before loop range
         if (startPosition < scheduleStartBeat && !options?.allowStartBeforeLoopStart) {
           startPosition = scheduleStartBeat;
         }
+
+        this.setPlaybackOrigin(project, startPosition >= scheduleStartBeat ? scheduleStartBeat : startPosition);
+
+        // Configure Tone.Transport loop boundaries
+        const loopStartTime = this.projectBeatToTransportTime(scheduleStartBeat);
+        const loopEndTime = this.projectBeatToTransportTime(scheduleEndBeat);
+        Tone.Transport.setLoopPoints(loopStartTime, loopEndTime);
+        Tone.Transport.loop = true;
+
+        console.log(`Loop mode enabled: bars [${startBar}, ${endBar}], beats [${scheduleStartBeat}, ${scheduleEndBeat}]`);
       } else {
         Tone.Transport.loop = false;
         console.log("Loop mode disabled");
+        this.setPlaybackOrigin(project, startPosition);
       }
 
       this.scheduleTempoChanges(project, Math.max(startPosition, scheduleStartBeat), scheduleEndBeat);
@@ -641,7 +646,7 @@ export class KGAudioInterface {
               if (audioBus.shouldPlayWithSolo(hasSoloedTracks)) {
                 audioBus.scheduleLiveMidiPitchBend(midiPitchBendToNormalized(value), time);
               }
-            }, this.beatsToToneTime(beat));
+            }, this.projectBeatToTransportTime(beat));
 
             this.scheduledEvents.add(eventId);
           });
@@ -669,7 +674,7 @@ export class KGAudioInterface {
               if (audioBus.shouldPlayWithSolo(hasSoloedTracks)) {
                 audioBus.scheduleLiveMidiExpression(value / 127, time);
               }
-            }, this.beatsToToneTime(beat));
+            }, this.projectBeatToTransportTime(beat));
 
             this.scheduledEvents.add(eventId);
           });
@@ -697,13 +702,13 @@ export class KGAudioInterface {
               if (audioBus.shouldPlayWithSolo(hasSoloedTracks)) {
                 audioBus.setLiveMidiSustain(value >= 64, time);
               }
-            }, this.beatsToToneTime(beat));
+            }, this.projectBeatToTransportTime(beat));
 
             this.scheduledEvents.add(eventId);
           });
 
           trackNotes.forEach(({ note, absoluteStartBeat, absoluteEndBeat }) => {
-            const noteStartTime = this.beatsToToneTime(absoluteStartBeat);
+            const noteStartTime = this.projectBeatToTransportTime(absoluteStartBeat);
             const noteDurationSeconds = beatRangeToSeconds(project, absoluteStartBeat, absoluteEndBeat);
             const velocity = note.getVelocity() / 127;
             const noteName = pitchToNoteNameString(note.getPitch());
@@ -781,7 +786,7 @@ export class KGAudioInterface {
                     return;
                   }
 
-                  const regionStartTime = this.beatsToToneTime(safeResumeBeat);
+                  const regionStartTime = this.projectBeatToTransportTime(safeResumeBeat);
 
                   const eventId = Tone.Transport.schedule((time) => {
                     const hasSoloedTracks = this.hasSoloedTracks();
@@ -819,7 +824,7 @@ export class KGAudioInterface {
                 effectiveDurationSeconds = Math.min(effectiveDurationSeconds, maxDurationSeconds);
               }
 
-              const regionStartTime = this.beatsToToneTime(regionStartBeat);
+              const regionStartTime = this.projectBeatToTransportTime(regionStartBeat);
 
               console.log(
                 `Scheduling audio region "${region.getName()}" at beat ${regionStartBeat}, clipOffset: ${clipStartOffsetSeconds}s, duration: ${effectiveDurationSeconds}s`
@@ -885,6 +890,7 @@ export class KGAudioInterface {
     try {
       this.clearDelayedTransportStart();
       Tone.Transport.stop();
+      this.resetPlaybackOrigin();
       this.metronome.stop();
 
       // Release all currently playing notes
@@ -1156,7 +1162,7 @@ export class KGAudioInterface {
     try {
       // Convert beats to Tone.js time format
       const safePosition = Math.max(0, position);
-      const toneTime = this.beatsToToneTime(safePosition);
+      const toneTime = this.projectBeatToTransportTime(safePosition);
       Tone.Transport.position = toneTime;
       console.log(`Set transport position to ${position} beats (${toneTime})`);
     } catch (error) {
@@ -1179,10 +1185,13 @@ export class KGAudioInterface {
 
       const transportSeconds = Number(Tone.Transport.seconds);
       if (Number.isFinite(transportSeconds)) {
-        return secondsToBeat(KGCore.instance().getCurrentProject(), transportSeconds);
+        return secondsToBeat(
+          KGCore.instance().getCurrentProject(),
+          this.playbackOriginSeconds + Math.max(0, transportSeconds)
+        );
       }
 
-      return this.toneTimeToBeats(Tone.Transport.position);
+      return this.transportTimeToProjectBeat(KGCore.instance().getCurrentProject(), Tone.Transport.position);
     } catch (error) {
       console.error('Error getting transport position:', error);
       return 0;
@@ -1455,7 +1464,7 @@ export class KGAudioInterface {
             playerBus.setAutomationVolume(value);
           }
           this.updateAllEffectiveVolumes();
-        }, this.beatsToToneTime(beat));
+        }, this.projectBeatToTransportTime(beat));
         this.scheduledEvents.add(eventId);
       });
 
@@ -1472,7 +1481,7 @@ export class KGAudioInterface {
           if (playerBus) {
             playerBus.scheduleAutomationPan(value, time);
           }
-        }, this.beatsToToneTime(beat));
+        }, this.projectBeatToTransportTime(beat));
         this.scheduledEvents.add(eventId);
       });
   }
@@ -1496,7 +1505,7 @@ export class KGAudioInterface {
 
       const eventId = Tone.Transport.schedule(() => {
         Tone.Transport.bpm.value = region.getBpm();
-      }, this.beatsToToneTime(regionStartBeat));
+      }, this.projectBeatToTransportTime(regionStartBeat));
       this.scheduledEvents.add(eventId);
     });
   }
@@ -1559,6 +1568,33 @@ export class KGAudioInterface {
     return beatToSeconds(KGCore.instance().getCurrentProject(), beats) as Tone.Unit.Time;
   }
 
+  private setPlaybackOrigin(project: KGProject, beat: number): void {
+    this.playbackOriginBeat = Math.max(0, beat);
+    this.playbackOriginSeconds = beatToSeconds(project, this.playbackOriginBeat);
+  }
+
+  private resetPlaybackOrigin(): void {
+    this.playbackOriginBeat = 0;
+    this.playbackOriginSeconds = 0;
+  }
+
+  private projectBeatToTransportTime(beat: number): Tone.Unit.Time {
+    const clampedBeat = Math.max(0, beat);
+    const transportBeats = Math.max(0, clampedBeat - this.playbackOriginBeat);
+    const transportTicks = Math.round(transportBeats * Tone.Transport.PPQ);
+    return transportTicks === 0 ? 0 : `${transportTicks}i` as Tone.Unit.Time;
+  }
+
+  private transportTimeToProjectBeat(project: KGProject, toneTime: Tone.Unit.Time): number {
+    if (typeof toneTime === 'string' && toneTime.endsWith('i')) {
+      const ticks = Number.parseFloat(toneTime.slice(0, -1));
+      return this.playbackOriginBeat + (Number.isFinite(ticks) ? ticks / Tone.Transport.PPQ : 0);
+    }
+
+    const numericTime = typeof toneTime === 'number' ? toneTime : Tone.Time(toneTime).toSeconds();
+    return this.playbackOriginBeat + Math.max(0, numericTime);
+  }
+
   /**
    * Convert Tone.js time format to beats
    */

src/core/audio-interface/KGOfflineRenderer.test.ts

@@ -1,6 +1,8 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { createMockMidiNote, createMockMidiRegion, createMockMidiTrack, createMockProject } from '../../test/utils/mock-data';
 import { bakeMidiAutomationPointsInWindow } from '../../util/midiAutomationUtil';
+import { GlobalTrackType } from '../global-track';
+import { KGTempoRegion } from '../region/KGTempoRegion';
 
 const { offlineMock, configGetMock } = vi.hoisted(() => ({
   offlineMock: vi.fn(),
@@ -32,6 +34,15 @@ vi.mock('../config/ConfigManager', () => ({
 
 import { KGOfflineRenderer, applyOfflinePitchBendAutomation, encodeWav, getOfflineTrackGain, getOfflineTrackVolumeDb } from './KGOfflineRenderer';
 
+function setTempoRegions(project: ReturnType<typeof createMockProject>, regions: KGTempoRegion[]): void {
+  const tempoTrack = project.getGlobalTracks().find(track => track.getType() === GlobalTrackType.Tempo);
+  if (!tempoTrack) {
+    throw new Error('Tempo track missing in test setup');
+  }
+
+  tempoTrack.setRegions(regions);
+}
+
 /**
  * Create a minimal AudioBuffer-like object for testing.
  * In the jsdom test environment, AudioBuffer is not available,
@@ -215,8 +226,8 @@ describe('offline pitch bend automation', () => {
       source,
       1,
       [{ beat: 1, value: 0 }],
+      createMockProject({ bpm: 120 }),
       0,
-      0.5
     );
 
     expect(calls).toHaveLength(1);
@@ -252,11 +263,43 @@ describe('offline pitch bend automation', () => {
       }
     );
 
-    applyOfflinePitchBendAutomation(source, 1, baked.filter(point => point.beat > 0), 0, 0.5);
+    applyOfflinePitchBendAutomation(source, 1, baked.filter(point => point.beat > 0), createMockProject({ bpm: 120 }), 0);
 
     expect(calls).toHaveLength(1);
     expect(calls[0][1]).toBe(0.26);
   });
+
+  it('uses tempo-aware automation timing after a BPM change', () => {
+    const source = {
+      playbackRate: {
+        value: 1,
+        setValueAtTime: (..._args: unknown[]) => undefined,
+      },
+    } as unknown as Parameters<typeof applyOfflinePitchBendAutomation>[0];
+
+    const calls: Array<[number, number]> = [];
+    source.playbackRate.setValueAtTime = ((value: number, time: number) => {
+      calls.push([value, time]);
+      return source.playbackRate as never;
+    }) as typeof source.playbackRate.setValueAtTime;
+
+    const project = createMockProject({ bpm: 120 });
+    setTempoRegions(project, [
+      new KGTempoRegion('tempo-a', 'tempo-track', 0, 120, 0, 1, 4),
+      new KGTempoRegion('tempo-b', 'tempo-track', 0, 60, 1, 31, 4),
+    ]);
+
+    applyOfflinePitchBendAutomation(
+      source,
+      1,
+      [{ beat: 5, value: 0 }],
+      project,
+      0,
+    );
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0][1]).toBe(3);
+  });
 });
 
 describe('renderToBuffer bounce range', () => {

src/core/audio-interface/KGOfflineRenderer.ts

@@ -96,7 +96,6 @@ export class KGOfflineRenderer {
 
     // Calculate render duration in seconds
     const bpm = getEffectiveBpmAtBeat(project, 0);
-    const secondsPerBeat = 60 / bpm;
     const timeSignature = project.getTimeSignature();
     const beatsPerBar = timeSignature.numerator;
 
@@ -304,7 +303,7 @@ export class KGOfflineRenderer {
 
         context.transport.schedule((time) => {
           context.transport.bpm.setValueAtTime(region.getBpm(), time);
-        }, beatToSeconds(project, regionStartBeat) - beatToSeconds(project, renderStartBeat));
+        }, beatsToOfflineTransportTime(regionStartBeat, renderStartBeat));
       });
 
       // ---- Create MIDI track samplers ----
@@ -343,9 +342,9 @@ export class KGOfflineRenderer {
               trackInfo.volumeAutomation,
               trackInfo.panAutomation,
               trackInfo.volume,
+              project,
               renderStartBeat,
               renderEndBeat,
-              secondsPerBeat,
               interpolationIntervalMs,
               bpm
             );
@@ -381,7 +380,6 @@ export class KGOfflineRenderer {
                 // Skip notes outside render range
                 if (note.startBeat >= renderEndBeat || note.endBeat <= renderStartBeat) continue;
 
-                const noteStartTime = beatToSeconds(project, note.startBeat) - beatToSeconds(project, renderStartBeat);
                 const sustainedEndBeat = resolveSustainExtendedEndBeat(
                   trackInfo.controllerEventsByType[64],
                   note.endBeat,
@@ -412,19 +410,19 @@ export class KGOfflineRenderer {
                   source,
                   basePlaybackRate,
                   bakedTrackPitchBends.filter(point => point.beat > note.startBeat && point.beat < sustainedEndBeat),
+                  project,
                   renderStartBeat,
-                  secondsPerBeat
                 );
                 applyOfflineExpressionAutomation(
                   gainNode,
                   bakedExpressionEvents.filter(point => point.beat > note.startBeat && point.beat < sustainedEndBeat),
+                  project,
                   renderStartBeat,
-                  secondsPerBeat
                 );
 
                 context.transport.schedule((time) => {
                   source.start(time, 0, noteDuration, velocity);
-                }, noteStartTime);
+                }, beatsToOfflineTransportTime(note.startBeat, renderStartBeat));
               }
             }
           } catch (error) {
@@ -449,9 +447,9 @@ export class KGOfflineRenderer {
           trackInfo.volumeAutomation,
           trackInfo.panAutomation,
           trackInfo.volume,
+          project,
           renderStartBeat,
           renderEndBeat,
-          secondsPerBeat,
           interpolationIntervalMs,
           bpm
         );
@@ -470,7 +468,7 @@ export class KGOfflineRenderer {
 
           if (effectiveDurationSeconds <= 0) continue;
 
-          const regionStartTime = Math.max(0, beatToSeconds(project, regionStartBeat) - beatToSeconds(project, renderStartBeat));
+          const regionStartTime = beatsToOfflineTransportTime(regionStartBeat, renderStartBeat);
 
           // Create buffer source NOW while the offline context is still active.
           // Schedule callbacks fire during rendering after Tone.js restores the
@@ -660,11 +658,11 @@ export function applyOfflinePitchBendAutomation(
   source: Tone.ToneBufferSource,
   basePlaybackRate: number,
   bakedPitchBends: BakedMidiAutomationPoint[],
+  project: KGProject,
   renderStartBeat: number,
-  secondsPerBeat: number
 ): void {
   bakedPitchBends.forEach(point => {
-    const automationTime = (point.beat - renderStartBeat) * secondsPerBeat;
+    const automationTime = beatToSeconds(project, point.beat) - beatToSeconds(project, renderStartBeat);
     setOfflinePlaybackRate(
       source,
       KGAudioBus.applyNormalizedPitchBendToPlaybackRate(basePlaybackRate, midiPitchBendToNormalized(point.value)),
@@ -676,11 +674,11 @@ export function applyOfflinePitchBendAutomation(
 export function applyOfflineExpressionAutomation(
   gainNode: Tone.Gain,
   bakedExpressionEvents: BakedMidiAutomationPoint[],
+  project: KGProject,
   renderStartBeat: number,
-  secondsPerBeat: number
 ): void {
   bakedExpressionEvents.forEach(point => {
-    const automationTime = (point.beat - renderStartBeat) * secondsPerBeat;
+    const automationTime = beatToSeconds(project, point.beat) - beatToSeconds(project, renderStartBeat);
     setOfflineGainValue(gainNode, clampMidiControllerValue(point.value) / 127, automationTime);
   });
 }
@@ -691,9 +689,9 @@ function applyOfflineTrackAutomation(
   volumeAutomation: MidiAutomationPoint[],
   panAutomation: MidiAutomationPoint[],
   baseVolume: number,
+  project: KGProject,
   renderStartBeat: number,
   renderEndBeat: number,
-  secondsPerBeat: number,
   interpolationIntervalMs: number,
   bpm: number
 ): void {
@@ -717,7 +715,7 @@ function applyOfflineTrackAutomation(
         return;
       }
 
-      const automationTime = (point.beat - renderStartBeat) * secondsPerBeat;
+      const automationTime = beatToSeconds(project, point.beat) - beatToSeconds(project, renderStartBeat);
       setOfflineGainValue(gainNode, getOfflineTrackGain(point.value, false), automationTime);
     });
   } else {
@@ -744,7 +742,7 @@ function applyOfflineTrackAutomation(
         return;
       }
 
-      const automationTime = (point.beat - renderStartBeat) * secondsPerBeat;
+      const automationTime = beatToSeconds(project, point.beat) - beatToSeconds(project, renderStartBeat);
       setOfflinePanValue(pannerNode, point.value, automationTime);
     });
   } else {
@@ -752,6 +750,12 @@ function applyOfflineTrackAutomation(
   }
 }
 
+function beatsToOfflineTransportTime(beat: number, renderStartBeat: number): Tone.Unit.Time {
+  const transportBeats = Math.max(0, beat - renderStartBeat);
+  const transportTicks = Math.round(transportBeats * Tone.Transport.PPQ);
+  return transportTicks === 0 ? 0 : `${transportTicks}i` as Tone.Unit.Time;
+}
+
 export function getOfflineTrackVolumeDb(volumeDb: number, muted: boolean): number {
   const isSilent = muted || volumeDb <= AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB;
   return isSilent ? -Infinity : volumeDb;