Better code quality

src/domain/audio/WavExporter.ts

@@ -1,13 +1,70 @@
-import { encodeWAV } from '../../lib/bytebeat/wavEncoder'
-import type { BitDepth } from '../../lib/bytebeat/types'
-
-export type { BitDepth }
+export type BitDepth = 8 | 16 | 24
 
 export interface ExportOptions {
   sampleRate: number
   bitDepth?: BitDepth
 }
 
+function encodeWAV(samples: Float32Array, sampleRate: number, bitDepth: BitDepth): Blob {
+  const numChannels = 1
+  const bytesPerSample = bitDepth / 8
+  const blockAlign = numChannels * bytesPerSample
+  const byteRate = sampleRate * blockAlign
+  const dataSize = samples.length * bytesPerSample
+  const bufferSize = 44 + dataSize
+
+  const buffer = new ArrayBuffer(bufferSize)
+  const view = new DataView(buffer)
+
+  const writeString = (offset: number, string: string) => {
+    for (let i = 0; i < string.length; i++) {
+      view.setUint8(offset + i, string.charCodeAt(i))
+    }
+  }
+
+  writeString(0, 'RIFF')
+  view.setUint32(4, 36 + dataSize, true)
+  writeString(8, 'WAVE')
+  writeString(12, 'fmt ')
+  view.setUint32(16, 16, true)
+  view.setUint16(20, 1, true)
+  view.setUint16(22, numChannels, true)
+  view.setUint32(24, sampleRate, true)
+  view.setUint32(28, byteRate, true)
+  view.setUint16(32, blockAlign, true)
+  view.setUint16(34, bitDepth, true)
+  writeString(36, 'data')
+  view.setUint32(40, dataSize, true)
+
+  const maxValue = Math.pow(2, bitDepth - 1) - 1
+  let offset = 44
+
+  for (let i = 0; i < samples.length; i++) {
+    const sample = Math.max(-1, Math.min(1, samples[i]))
+    const intSample = Math.round(sample * maxValue)
+
+    if (bitDepth === 8) {
+      view.setUint8(offset, intSample + 128)
+      offset += 1
+    } else if (bitDepth === 16) {
+      view.setInt16(offset, intSample, true)
+      offset += 2
+    } else if (bitDepth === 24) {
+      const bytes = [
+        intSample & 0xff,
+        (intSample >> 8) & 0xff,
+        (intSample >> 16) & 0xff
+      ]
+      view.setUint8(offset, bytes[0])
+      view.setUint8(offset + 1, bytes[1])
+      view.setUint8(offset + 2, bytes[2])
+      offset += 3
+    }
+  }
+
+  return new Blob([buffer], { type: 'audio/wav' })
+}
+
 export function exportToWav(
   samples: Float32Array,
   options: ExportOptions