Streaming transcription

Transcribe live audio over a WebSocket, with interim results.

Open a WebSocket, push audio, receive text as it is recognised.

wss://stt.omnia-voice.com/stream

Authenticating

Subprotocol (recommended)

Pass the key as a WebSocket subprotocol. It never appears in a URL, so it stays out of proxy and server logs.

const ws = new WebSocket(
  "wss://stt.omnia-voice.com/stream",
  ["token", "your_api_key"]
);

First message (fallback)

For clients that cannot set subprotocols, authenticate with the first message.

const ws = new WebSocket("wss://stt.omnia-voice.com/stream");

ws.onopen = () => {
  ws.send(JSON.stringify({ type: "auth", apiKey: "your_api_key" }));
};

Never do either of these from a browser you do not control — the key is visible to anyone who opens devtools. Stream from your server, or proxy through it.

Sending audio

Wait for ready, then send binary chunks:

• 16 kHz, 16-bit PCM, mono
• 20 ms per chunk — 640 bytes

ws.onmessage = (event) => {
  const msg = JSON.parse(event.data);

  if (msg.type === "ready") {
    startMicrophone();
  }

  if (msg.type === "transcript") {
    console.log(msg.isFinal ? "[FINAL]" : "[interim]", msg.transcript);
  }
};

// binary frames, not JSON
ws.send(audioChunk);

Messages you receive

ready · object

Authentication succeeded. Start sending audio.

transcript · object

A result. transcript holds the text; isFinal says whether it is settled.

Interim results arrive fast and may be revised — good for showing live captions. Final results are stable — use those for anything you store or act on.

error · object

Something went wrong. message explains what.

A complete example

const ws = new WebSocket(
  "wss://stt.omnia-voice.com/stream",
  ["token", process.env.OMNIA_API_KEY]
);

let finalText = "";

ws.onmessage = (event) => {
  const msg = JSON.parse(event.data);

  if (msg.type === "ready") {
    console.log("ready — streaming");
  }

  if (msg.type === "transcript") {
    if (msg.isFinal) {
      finalText += msg.transcript + " ";
      render(finalText, "");
    } else {
      render(finalText, msg.transcript);   // show the tail as provisional
    }
  }

  if (msg.type === "error") {
    console.error(msg.message);
  }
};

ws.onclose = () => console.log("closed:", finalText.trim());

Render finals and interims differently — settled text in your normal colour, the interim tail dimmed. Users read a caption that visibly firms up as accurate; one that silently rewrites itself reads as broken.

Keeping the stream healthy

• Send steadily. Bursting a buffer is worse than a paced 20 ms cadence.
• Reconnect on close. Networks drop; keep the transcript you already finalised and resume.
• Close cleanly when you stop, so the last partial result is flushed.