Audio archive

Follow along with the runnable example. This guide walks through the Audio archive example in corti-examples — bootstrap your build from it or use it as reference.

Some workflows need to keep the audio a user dictated — for playback, quality review, or later re-transcription. This guide shows where to capture that audio and how to persist it while streaming to Corti. It builds on the raw-SDK path from the Microphone guide, where your app owns MediaRecorder directly — that’s the point at which each audio chunk is available to both send and keep.

Tee each chunk

The only change from a plain raw-SDK session is what you do in ondataavailable: append the chunk to a local archive and send it to Corti. Both consume the same blob.

JavaScript

recorder.ondataavailable = async (e) => {
  if (e.data.size === 0) return;
  await appendChunk(e.data);                       // persist locally
  // pass e.data.arrayBuffer() to socket.sendAudio() to stream to Corti
};

Session lifecycle

Model recording as a session with three controls, so a user can pause and resume without dropping the connection:

Control	Effect
Record	Open a new session (or resume a paused one) and start capturing
Stop	Flush buffered audio, then pause the recorder — the socket stays open
End session	Flush, finalize the archive, and close the socket

The key detail is flushing before you pause or end: calling socket.sendFlush() tells the server to return transcripts for audio it has already received, so nothing is lost at the boundary.

JavaScript

// Stop: emit a final chunk, then pause (keep the socket open).
async function stop() {
  recorder.requestData();   // force a last ondataavailable
  recorder.pause();
}

Call socket.sendFlush() after pausing — the server returns any buffered transcripts and then a flushed message signalling completion. See the audio archive example in corti-examples for the full socket flush implementation.

Finalize the archive

On End session, assemble the collected chunks into a single Blob using the recorder’s actual MIME type, then build a playback/download URL.

JavaScript

const mimeType = recorder.mimeType || "audio/webm"; // what MediaRecorder actually produced
const blob = new Blob(chunks, { type: mimeType });
const url = URL.createObjectURL(blob);              // <audio src>, or a download link

Capture a little metadata alongside the blob so the archive is useful later — the device label, the actual capture MIME, segment start/end reasons and durations, and total chunk/byte counts. Derive the file extension from the MIME type (audio/webm → .webm, audio/mp4 → .m4a) and give the file a timestamped name.

This example stores audio in the browser for demonstration. In production, dictation audio is often sensitive — persist it to a secure server-side store, and apply your organization’s retention and access policies rather than keeping it client-side.

Next steps

Microphone

The raw-SDK capture path this archive builds on.

File Transcription

Re-transcribe an archived recording offline via /transcripts.

Example code

The complete, runnable Audio archive example in corti-examples.

Please contact us for help or questions.

Endpoints

Features

Best Practices

Guides

Resources

Tee each chunk

Session lifecycle

Finalize the archive

Next steps

Microphone

File Transcription

Example code

​Tee each chunk

​Session lifecycle

​Finalize the archive

​Next steps

Microphone

File Transcription

Example code

Tee each chunk

Session lifecycle

Finalize the archive

Next steps