chore(integration): snapshot local main worktree

src/lib/voice-recording.ts

@@ -0,0 +1,90 @@
+const VOICE_WAV_SAMPLE_RATE = 16_000;
+const VOICE_WAV_CHANNELS = 1;
+const VOICE_WAV_BITS_PER_SAMPLE = 16;
+
+type OfflineAudioContextConstructor = new (
+  numberOfChannels: number,
+  length: number,
+  sampleRate: number,
+) => OfflineAudioContext;
+
+type AudioContextWindow = Window & {
+  webkitAudioContext?: typeof AudioContext;
+  webkitOfflineAudioContext?: OfflineAudioContextConstructor;
+};
+
+export async function blobToBase64(blob: Blob): Promise<string> {
+  const bytes = new Uint8Array(await blob.arrayBuffer());
+  let binary = '';
+  const chunkSize = 0x8000;
+  for (let index = 0; index < bytes.length; index += chunkSize) {
+    binary += String.fromCharCode(...bytes.subarray(index, index + chunkSize));
+  }
+  return btoa(binary);
+}
+
+function writeAscii(view: DataView, offset: number, value: string): void {
+  for (let index = 0; index < value.length; index += 1) {
+    view.setUint8(offset + index, value.charCodeAt(index));
+  }
+}
+
+function audioBufferTo16BitPcmWav(audioBuffer: AudioBuffer): Blob {
+  const samples = audioBuffer.getChannelData(0);
+  const bytesPerSample = VOICE_WAV_BITS_PER_SAMPLE / 8;
+  const blockAlign = VOICE_WAV_CHANNELS * bytesPerSample;
+  const dataSize = samples.length * blockAlign;
+  const wavBuffer = new ArrayBuffer(44 + dataSize);
+  const view = new DataView(wavBuffer);
+
+  writeAscii(view, 0, 'RIFF');
+  view.setUint32(4, 36 + dataSize, true);
+  writeAscii(view, 8, 'WAVE');
+  writeAscii(view, 12, 'fmt ');
+  view.setUint32(16, 16, true);
+  view.setUint16(20, 1, true);
+  view.setUint16(22, VOICE_WAV_CHANNELS, true);
+  view.setUint32(24, VOICE_WAV_SAMPLE_RATE, true);
+  view.setUint32(28, VOICE_WAV_SAMPLE_RATE * blockAlign, true);
+  view.setUint16(32, blockAlign, true);
+  view.setUint16(34, VOICE_WAV_BITS_PER_SAMPLE, true);
+  writeAscii(view, 36, 'data');
+  view.setUint32(40, dataSize, true);
+
+  let offset = 44;
+  for (const sample of samples) {
+    const clamped = Math.max(-1, Math.min(1, sample));
+    view.setInt16(offset, clamped < 0 ? clamped * 0x8000 : clamped * 0x7fff, true);
+    offset += bytesPerSample;
+  }
+  return new Blob([new Uint8Array(wavBuffer)], { type: 'audio/wav' });
+}
+
+export async function convertAudioBlobTo16kMonoWav(audioBlob: Blob): Promise<Blob> {
+  const audioWindow = window as AudioContextWindow;
+  const AudioContextCtor = window.AudioContext ?? audioWindow.webkitAudioContext;
+  const OfflineAudioContextCtor = window.OfflineAudioContext
+    ?? audioWindow.webkitOfflineAudioContext;
+  if (!AudioContextCtor || !OfflineAudioContextCtor) {
+    throw new Error('当前环境无法转换录音');
+  }
+
+  const audioContext = new AudioContextCtor();
+  let decodedBuffer: AudioBuffer;
+  try {
+    decodedBuffer = await audioContext.decodeAudioData(await audioBlob.arrayBuffer());
+  } finally {
+    await audioContext.close().catch(() => undefined);
+  }
+  const frameCount = Math.max(1, Math.ceil(decodedBuffer.duration * VOICE_WAV_SAMPLE_RATE));
+  const offlineContext = new OfflineAudioContextCtor(
+    VOICE_WAV_CHANNELS,
+    frameCount,
+    VOICE_WAV_SAMPLE_RATE,
+  );
+  const source = offlineContext.createBufferSource();
+  source.buffer = decodedBuffer;
+  source.connect(offlineContext.destination);
+  source.start(0);
+  return audioBufferTo16BitPcmWav(await offlineContext.startRendering());
+}