Create WAV header for PCM data

createWavHeader.ts

export function createWavHeader(dataLength: number, sampleRate: number, bitDepth: number, channels: number) {
  const headerLength = 44; // Standard size of WAV header
  const totalLength = headerLength + dataLength;

  const buffer = new ArrayBuffer(headerLength);
  const view = new DataView(buffer);

  // RIFF chunk descriptor
  writeString(view, 0, 'RIFF'); // ChunkID
  view.setUint32(4, totalLength - 8, true); // ChunkSize (file size - 8 bytes)
  writeString(view, 8, 'WAVE'); // Format

  // fmt subchunk (format details)
  writeString(view, 12, 'fmt '); // Subchunk1ID
  view.setUint32(16, 16, true); // Subchunk1Size (16 for PCM)
  view.setUint16(20, 1, true); // AudioFormat (1 for PCM)
  view.setUint16(22, channels, true); // NumChannels
  view.setUint32(24, sampleRate, true); // SampleRate
  view.setUint32(28, sampleRate * channels * bitDepth / 8, true); // ByteRate
  view.setUint16(32, channels * bitDepth / 8, true); // BlockAlign
  view.setUint16(34, bitDepth, true); // BitsPerSample

  // data subchunk (actual sound data)
  writeString(view, 36, 'data'); // Subchunk2ID
  view.setUint32(40, dataLength, true); // Subchunk2Size

  return buffer;

  function writeString(view: DataView, offset: number, string: string) {
      for (let i = 0; i < string.length; i++) {
          view.setUint8(offset + i, string.charCodeAt(i));
      }
  }
}