/** A mono float trace as 16-bit PCM .wav bytes, clipped to [-1, 1]. The
 *  mix is already levelled and at the mix rate, so no resampling or
 *  normalization happens here. */
export function wavBytes(samples: Float32Array, sr: number): Uint8Array {
  const n = samples.length;
  const buf = new ArrayBuffer(44 + 2 * n);
  const view = new DataView(buf);
  const str = (off: number, s: string): void => {
    for (let i = 0; i < s.length; i++) view.setUint8(off + i, s.charCodeAt(i));
  };
  str(0, 'RIFF');
  view.setUint32(4, 36 + 2 * n, true);
  str(8, 'WAVE');
  str(12, 'fmt ');
  view.setUint32(16, 16, true);
  view.setUint16(20, 1, true);   // PCM
  view.setUint16(22, 1, true);   // mono
  view.setUint32(24, sr, true);
  view.setUint32(28, 2 * sr, true);
  view.setUint16(32, 2, true);
  view.setUint16(34, 16, true);
  str(36, 'data');
  view.setUint32(40, 2 * n, true);
  for (let i = 0; i < n; i++) {
    const v = Math.max(-1, Math.min(1, samples[i]));
    view.setInt16(44 + 2 * i, Math.round(v * 32767), true);
  }
  return new Uint8Array(buf);
}