OK ready

public/worklets/chorus-processor.js

@@ -0,0 +1,167 @@
+class ChorusProcessor extends AudioWorkletProcessor {
+  constructor() {
+    super()
+
+    this.mode = 'chorus'
+    this.rate = 0.5
+    this.depth = 0.5
+    this.feedback = 0
+    this.spread = 0.3
+    this.bypassed = false
+
+    this.delayBufferSize = Math.floor(sampleRate * 0.05)
+    this.delayBufferL = new Float32Array(this.delayBufferSize)
+    this.delayBufferR = new Float32Array(this.delayBufferSize)
+    this.writeIndex = 0
+
+    this.lfoPhase = 0
+    this.lfoPhaseRight = 0
+
+    this.port.onmessage = (event) => {
+      const { type, value } = event.data
+      switch (type) {
+        case 'mode':
+          this.mode = value
+          break
+        case 'frequency':
+          this.rate = value
+          break
+        case 'depth':
+          this.depth = value
+          break
+        case 'feedback':
+          this.feedback = value
+          break
+        case 'spread':
+          this.spread = value
+          break
+        case 'bypass':
+          this.bypassed = value
+          break
+      }
+    }
+  }
+
+  processChorus(sampleL, sampleR) {
+    const baseDelay = 15
+    const maxDepth = 8
+
+    this.lfoPhase += this.rate / sampleRate
+    this.lfoPhaseRight += this.rate / sampleRate
+
+    if (this.lfoPhase >= 1) this.lfoPhase -= 1
+    if (this.lfoPhaseRight >= 1) this.lfoPhaseRight -= 1
+
+    const spreadPhase = this.spread * 0.5
+    const lfoL = Math.sin(this.lfoPhase * Math.PI * 2)
+    const lfoR = Math.sin((this.lfoPhaseRight + spreadPhase) * Math.PI * 2)
+
+    const delayTimeL = baseDelay + lfoL * maxDepth * this.depth
+    const delayTimeR = baseDelay + lfoR * maxDepth * this.depth
+
+    const delaySamplesL = (delayTimeL / 1000) * sampleRate
+    const delaySamplesR = (delayTimeR / 1000) * sampleRate
+
+    const readIndexL = (this.writeIndex - delaySamplesL + this.delayBufferSize) % this.delayBufferSize
+    const readIndexR = (this.writeIndex - delaySamplesR + this.delayBufferSize) % this.delayBufferSize
+
+    const readIndexL0 = Math.floor(readIndexL) % this.delayBufferSize
+    const readIndexL1 = (readIndexL0 + 1) % this.delayBufferSize
+    const fracL = readIndexL - Math.floor(readIndexL)
+
+    const readIndexR0 = Math.floor(readIndexR) % this.delayBufferSize
+    const readIndexR1 = (readIndexR0 + 1) % this.delayBufferSize
+    const fracR = readIndexR - Math.floor(readIndexR)
+
+    const delayedL = this.delayBufferL[readIndexL0] * (1 - fracL) + this.delayBufferL[readIndexL1] * fracL
+    const delayedR = this.delayBufferR[readIndexR0] * (1 - fracR) + this.delayBufferR[readIndexR1] * fracR
+
+    this.delayBufferL[this.writeIndex] = sampleL + delayedL * this.feedback
+    this.delayBufferR[this.writeIndex] = sampleR + delayedR * this.feedback
+
+    return [delayedL, delayedR]
+  }
+
+  processFlanger(sampleL, sampleR) {
+    const baseDelay = 1
+    const maxDepth = 5
+
+    this.lfoPhase += this.rate / sampleRate
+    this.lfoPhaseRight += this.rate / sampleRate
+
+    if (this.lfoPhase >= 1) this.lfoPhase -= 1
+    if (this.lfoPhaseRight >= 1) this.lfoPhaseRight -= 1
+
+    const spreadPhase = this.spread * 0.5
+    const lfoL = Math.sin(this.lfoPhase * Math.PI * 2)
+    const lfoR = Math.sin((this.lfoPhaseRight + spreadPhase) * Math.PI * 2)
+
+    const delayTimeL = baseDelay + lfoL * maxDepth * this.depth
+    const delayTimeR = baseDelay + lfoR * maxDepth * this.depth
+
+    const delaySamplesL = (delayTimeL / 1000) * sampleRate
+    const delaySamplesR = (delayTimeR / 1000) * sampleRate
+
+    const readIndexL = (this.writeIndex - delaySamplesL + this.delayBufferSize) % this.delayBufferSize
+    const readIndexR = (this.writeIndex - delaySamplesR + this.delayBufferSize) % this.delayBufferSize
+
+    const readIndexL0 = Math.floor(readIndexL) % this.delayBufferSize
+    const readIndexL1 = (readIndexL0 + 1) % this.delayBufferSize
+    const fracL = readIndexL - Math.floor(readIndexL)
+
+    const readIndexR0 = Math.floor(readIndexR) % this.delayBufferSize
+    const readIndexR1 = (readIndexR0 + 1) % this.delayBufferSize
+    const fracR = readIndexR - Math.floor(readIndexR)
+
+    const delayedL = this.delayBufferL[readIndexL0] * (1 - fracL) + this.delayBufferL[readIndexL1] * fracL
+    const delayedR = this.delayBufferR[readIndexR0] * (1 - fracR) + this.delayBufferR[readIndexR1] * fracR
+
+    this.delayBufferL[this.writeIndex] = sampleL + delayedL * this.feedback * 0.9
+    this.delayBufferR[this.writeIndex] = sampleR + delayedR * this.feedback * 0.9
+
+    return [delayedL, delayedR]
+  }
+
+  process(inputs, outputs) {
+    const input = inputs[0]
+    const output = outputs[0]
+
+    if (!input || input.length === 0 || !output || output.length === 0) {
+      return true
+    }
+
+    const inputL = input[0]
+    const inputR = input[1] || input[0]
+    const outputL = output[0]
+    const outputR = output[1] || output[0]
+
+    if (!inputL || !outputL) {
+      return true
+    }
+
+    for (let i = 0; i < inputL.length; i++) {
+      if (this.bypassed) {
+        outputL[i] = inputL[i]
+        if (outputR) outputR[i] = inputR[i]
+        continue
+      }
+
+      let processedL, processedR
+
+      if (this.mode === 'flanger') {
+        [processedL, processedR] = this.processFlanger(inputL[i], inputR[i])
+      } else {
+        [processedL, processedR] = this.processChorus(inputL[i], inputR[i])
+      }
+
+      outputL[i] = processedL
+      if (outputR) outputR[i] = processedR
+
+      this.writeIndex = (this.writeIndex + 1) % this.delayBufferSize
+    }
+
+    return true
+  }
+}
+
+registerProcessor('chorus-processor', ChorusProcessor)