voice-stream/src/utils/downsample-buffer.ts

A powerful React hook for real-time voice streaming, designed for AI-powered applications. Perfect for real-time transcription, voice assistants, and audio processing with features like silence detection and configurable audio processing.

export const downsampleBuffer = (
  buffer: Float32Array,
  sampleRate: number,
  outSampleRate: number
): Int16Array => {
  if (outSampleRate === sampleRate) {
    const result = new Int16Array(buffer.length);
    for (let i = 0; i < buffer.length; i++) {
      const s = Math.max(-1, Math.min(1, buffer[i]));
      result[i] = s < 0 ? s * 0x8000 : s * 0x7fff;
    }
    return result;
  }
  const sampleRateRatio = sampleRate / outSampleRate;
  const newLength = Math.round(buffer.length / sampleRateRatio);
  const result = new Int16Array(newLength);
  let offsetResult = 0;
  let offsetBuffer = 0;
  while (offsetResult < newLength) {
    const nextOffsetBuffer = Math.round((offsetResult + 1) * sampleRateRatio);
    let accum = 0;
    let count = 0;
    for (let i = offsetBuffer; i < nextOffsetBuffer && i < buffer.length; i++) {
      accum += buffer[i];
      count++;
    }
    const avg = accum / count;
    const s = Math.max(-1, Math.min(1, avg));
    result[offsetResult] = s < 0 ? s * 0x8000 : s * 0x7fff;
    offsetResult++;
    offsetBuffer = nextOffsetBuffer;
  }
  return result;
};