Live streaming

"""Stream a 16-bit mono WAV file to Audrey in 20 ms chunks and print each final.

pip install websockets   (version 13 or newer)
python stream.py call.wav
"""
import asyncio
import json
import os
import sys
import wave

import websockets

URL = "wss://api.p99lab.com/v1/stream"
KEY = os.environ["P99LAB_API_KEY"]


async def send_audio(ws, path):
    with wave.open(path, "rb") as w:
        if w.getsampwidth() != 2 or w.getnchannels() != 1:
            raise SystemExit("need a 16-bit mono WAV file")
        rate = w.getframerate()
        if rate not in (8000, 16000, 24000, 48000):
            raise SystemExit("resample to 8, 16, 24 or 48 kHz first")
        await ws.send(json.dumps({"language": "en", "sample_rate": rate, "format": True}))
        frames = rate // 50                       # 20 ms of audio
        while chunk := w.readframes(frames):
            await ws.send(chunk)
            await asyncio.sleep(0.02)             # real time, as a live call would
    await ws.send(json.dumps({"type": "flush"}))  # finalise the last utterance now
    await ws.send(json.dumps({"type": "end"}))


async def main(path):
    finals = []
    async with websockets.connect(URL, additional_headers={"Authorization": f"Bearer {KEY}"}) as ws:
        sender = asyncio.create_task(send_audio(ws, path))
        try:
            async for raw in ws:
                msg = json.loads(raw)
                if msg["type"] == "final":
                    print(f"[{msg['start']:7.2f} - {msg['end']:7.2f}] {msg['text']}")
                    finals.append(msg["text"])
                elif msg["type"] == "error":
                    raise RuntimeError(msg["message"])
                elif msg["type"] == "done":
                    break
        finally:
            sender.cancel()
    print("\n" + " ".join(t for t in finals if t))


if __name__ == "__main__":
    asyncio.run(main(sys.argv[1] if len(sys.argv) > 1 else "call.wav"))

// Stream a 16-bit mono WAV file to Audrey in 20 ms chunks and print each final.
// Node.js 22 or newer (built-in WebSocket), no packages:  node stream.mjs call.wav
import { readFileSync } from "node:fs";

const URL = "wss://api.p99lab.com/v1/stream";
const KEY = process.env.P99LAB_API_KEY;

function readWav(buf) {
  let off = 12, fmt = null, data = null;
  while (off + 8 <= buf.length) {
    const id = buf.toString("ascii", off, off + 4);
    const size = buf.readUInt32LE(off + 4);
    if (id === "fmt ") fmt = { channels: buf.readUInt16LE(off + 10), rate: buf.readUInt32LE(off + 12), bits: buf.readUInt16LE(off + 22) };
    if (id === "data") data = buf.subarray(off + 8, off + 8 + size);
    off += 8 + size + (size % 2);
  }
  if (!fmt || !data || fmt.channels !== 1 || fmt.bits !== 16) throw new Error("need a 16-bit mono WAV file");
  if (![8000, 16000, 24000, 48000].includes(fmt.rate)) throw new Error("resample to 8, 16, 24 or 48 kHz first");
  return { rate: fmt.rate, pcm: data };
}

const { rate, pcm } = readWav(readFileSync(process.argv[2] ?? "call.wav"));
const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
const finals = [];
const ws = new WebSocket(URL);

ws.addEventListener("open", async () => {
  // Node's WebSocket cannot set headers, so the key goes in the configuration message.
  ws.send(JSON.stringify({ key: KEY, language: "en", sample_rate: rate, format: true }));
  const step = (rate / 50) * 2; // 20 ms of 16-bit samples, in bytes
  for (let i = 0; i < pcm.length && ws.readyState === WebSocket.OPEN; i += step) {
    ws.send(pcm.subarray(i, i + step));
    await sleep(20); // real time, as a live call would
  }
  if (ws.readyState === WebSocket.OPEN) {
    ws.send(JSON.stringify({ type: "flush" })); // finalise the last utterance now
    ws.send(JSON.stringify({ type: "end" }));
  }
});

ws.addEventListener("message", (event) => {
  const msg = JSON.parse(event.data);
  if (msg.type === "final") {
    console.log(`[${msg.start.toFixed(2)} - ${msg.end.toFixed(2)}] ${msg.text}`);
    finals.push(msg.text);
  } else if (msg.type === "error") {
    console.error(`error: ${msg.message}`);
    ws.close();
  } else if (msg.type === "done") {
    console.log("\n" + finals.filter(Boolean).join(" "));
    ws.close();
  }
});