Vendor soundtouch as local audio module

Author: walterlow

package-lock.json

@@ -76,7 +76,6 @@
     "react-hotkeys-hook": "^5.2.1",
     "react-resizable-panels": "^3.0.6",
     "sonner": "^2.0.7",
-    "soundtouchjs": "^0.2.1",
     "tailwind-merge": "^2.6.0",
     "tailwindcss-animate": "^1.0.7",
     "zod": "^4.1.12",

package.json

@@ -1,4 +1,4 @@
-import { SimpleFilter, SoundTouch } from 'soundtouchjs'
+import { TimeStretchFilter, TimeStretchProcessor } from '@/lib/audio/time-stretch'
 import {
   SOUND_TOUCH_PREVIEW_PROCESSOR_NAME,
   type SoundTouchPreviewProcessorMessage,
@@ -22,12 +22,12 @@ declare function registerProcessor(
 
 class SoundTouchPreviewProcessor extends AudioWorkletProcessor {
   private readonly source = new QueuedStereoBufferSource()
-  private readonly soundTouch = new SoundTouch()
-  private readonly filter = new SimpleFilter(
+  private readonly processor = new TimeStretchProcessor()
+  private readonly filter = new TimeStretchFilter(
     this.source as {
       extract: (target: Float32Array, numFrames: number, sourcePosition?: number) => number
     },
-    this.soundTouch,
+    this.processor,
   )
   private scratch = new Float32Array(256)
   private playing = false
@@ -43,9 +43,9 @@ class SoundTouchPreviewProcessor extends AudioWorkletProcessor {
   }
 
   private applySettings(): void {
-    this.soundTouch.tempo = Math.max(0.01, this.tempo)
-    this.soundTouch.pitch = Math.max(0.01, this.pitch)
-    this.soundTouch.rate = 1
+    this.processor.tempo = Math.max(0.01, this.tempo)
+    this.processor.pitch = Math.max(0.01, this.pitch)
+    this.processor.rate = 1
   }
 
   private handleMessage(message: SoundTouchPreviewProcessorMessage): void {

src/features/composition-runtime/worklets/soundtouch-preview-processor.worklet.ts

@@ -1416,8 +1416,8 @@ function applyClipFadeSpans(
 }
 
 /**
- * Apply speed change to audio with pitch preservation using SoundTouch algorithm.
- * Processes all channels together through a single SoundTouch instance so that
+ * Apply speed change to audio with pitch preservation using the local time-stretch processor.
+ * Processes all channels together through a single processor instance so that
  * WSOLA overlap windows are consistent across channels (prevents phase drift
  * between L/R that causes a hollow sound).
  *
@@ -1432,31 +1432,31 @@ async function applySpeedAndPitch(
   pitchShiftSemitones: number,
   sampleRate: number,
 ): Promise<Float32Array[]> {
-  const requiresSoundTouch =
+  const requiresTimeStretch =
     Math.abs(speed - 1) > 0.0001 || isAudioPitchShiftActive(pitchShiftSemitones)
-  if (!requiresSoundTouch) return channels
+  if (!requiresTimeStretch) return channels
   if (channels.length === 0 || channels[0]!.length === 0) return channels
 
   const numChannels = channels.length
   const samplesPerChannel = channels[0]!.length
 
-  log.debug('Applying speed/pitch change (SoundTouch)', {
+  log.debug('Applying speed/pitch change with time-stretch processor', {
     speed,
     pitchShiftSemitones,
     sampleRate,
     numChannels,
   })
 
   try {
-    const soundtouch = await import('soundtouchjs')
-    const st = new soundtouch.SoundTouch()
+    const timeStretch = await import('@/lib/audio/time-stretch')
+    const st = new timeStretch.TimeStretchProcessor()
 
     st.tempo = speed
     st.pitch = getAudioPitchRatioFromSemitones(pitchShiftSemitones)
     st.rate = 1.0
 
-    // SoundTouch processes interleaved stereo. Interleave all channels
-    // (for mono, duplicate to stereo so SoundTouch gets valid input).
+    // The processor consumes interleaved stereo. Interleave all channels
+    // (for mono, duplicate to stereo so it gets valid input).
     const stereoInput = new Float32Array(samplesPerChannel * 2)
     const left = channels[0]!
     const right = numChannels >= 2 ? channels[1]! : left
@@ -1479,7 +1479,7 @@ async function applySpeedAndPitch(
       },
     }
 
-    const filter = new soundtouch.SimpleFilter(source, st)
+    const filter = new timeStretch.TimeStretchFilter(source, st)
 
     const expectedOutputLength = Math.floor(samplesPerChannel / speed)
     const stereoOutput = new Float32Array(expectedOutputLength * 2)
@@ -1522,7 +1522,7 @@ async function applySpeedAndPitch(
       outputChannels.push(outLeft)
     }
 
-    log.debug('SoundTouch time stretch complete', {
+    log.debug('Time-stretch processing complete', {
       inputLength: samplesPerChannel,
       outputLength: actualOutputLength,
       expectedLength: expectedOutputLength,
@@ -1532,14 +1532,14 @@ async function applySpeedAndPitch(
 
     return outputChannels
   } catch (error) {
-    log.warn('SoundTouch failed, falling back to simple resampling', {
+    log.warn('Time-stretch processing failed, falling back to simple resampling', {
       error,
       speed,
       pitchShiftSemitones,
     })
 
     if (isAudioPitchShiftActive(pitchShiftSemitones)) {
-      log.warn('Independent export pitch shift was skipped because SoundTouch failed to load')
+      log.warn('Independent export pitch shift was skipped because time-stretch processing failed')
     }
 
     // Fallback: simple resampling per-channel (speed only, pitch shift omitted)
@@ -1767,7 +1767,7 @@ export async function processAudio(
       // Note: decoded audio is already trimmed to the range we requested.
 
       // Apply speed across ALL channels at once to maintain phase coherence
-      // between L/R (SoundTouch WSOLA finds shared overlap windows).
+      // between L/R (the WSOLA pipeline finds shared overlap windows).
       let processedChannels = decoded.samples
       if (
         Math.abs(segment.speed - 1) > 0.0001 ||