Amazon Nova 2 Sonic

import WebSocket from "ws";
import { randomUUID } from "node:crypto";
import { readFile, writeFile } from "node:fs/promises";

// Mono PCM16 at 16 kHz, paced like microphone input.
const input = await readFile("recording.pcm");
const url = new URL("/v1/audio/conversations/stream", process.env.AUDIOLAB_API_URL);
url.protocol = url.protocol === "https:" ? "wss:" : "ws:";
const socket = new WebSocket(url, {
  headers: { Authorization: `Bearer ${process.env.AUDIOLAB_API_KEY}`, "Idempotency-Key": randomUUID() },
});
let timer, offset = 0, chunk = 0;
const output = [];
socket.on("open", () => socket.send(JSON.stringify({
  type: "session.start", model: "amazon/nova-2-sonic", voice: "auto", max_seconds: 30,
})));
socket.on("message", raw => {
  const event = JSON.parse(raw.toString());
  if (event.type === "session.ready") timer = setInterval(() => {
    const frame = Buffer.alloc(640);
    if (offset < input.length) input.copy(frame, 0, offset, Math.min(offset + 640, input.length));
    offset += 640;
    if (socket.readyState === WebSocket.OPEN) socket.send(frame);
  }, 20);
  if (event.type === "output_audio.delta") {
    output.push(Buffer.from(event.delta, "base64"));
  }
  if (event.type === "output_audio.done") { clearInterval(timer); socket.send(JSON.stringify({ type: "session.finish" })); }
  if (event.type === "session.completed" || event.type === "error") console.log(event);
});
socket.on("close", () => {
  clearInterval(timer);
  void writeFile("response.pcm", Buffer.concat(output)).catch(console.error); // 24 kHz PCM16.
});
socket.on("error", console.error);