WTRecorder

WTRecorder is a JavaScript library that enables media recording and low-latency transmission using the WebTransport and MediaRecorder APIs. It is designed for real-time media streaming applications requiring efficient media capture and transmission.

Installation

To install the package, use npm:

npm install @mastashake08/wt-recorder

Importing the Library

Ensure that your project supports ES Modules by:

• Adding "type": "module" in package.json
• OR renaming your file to .mjs

import { WTRecorder } from '@mastashake08/wt-recorder';

Usage

Obtaining a Media Stream

To capture video and audio from the user's device:

const stream = await navigator.mediaDevices.getUserMedia({ video: true, audio: true });

Creating an Instance and Starting the Recorder

const serverUrl = "https://your-server.com/webtransport";
const wtOptions = { allowPooling: true }; // Optional WebTransport configuration

const recorder = new WTRecorder(serverUrl, stream, wtOptions);
await recorder.start(500); // Start recording with a 500ms timeslice

Stopping the Recorder and Retrieving the Recorded Data

setTimeout(async () => {
  await recorder.stop();
  const recordedBlob = recorder.getRecordedBlob();
  console.log("Recorded Blob:", recordedBlob);
}, 5000); // Stop recording after 5 seconds

API Reference

WTRecorder Constructor

const recorder = new WTRecorder(serverUrl, stream, wtOptions, mimeType);

Parameters

• serverUrl (string) – WebTransport server URL.
• stream (MediaStream) – Video/audio stream to be recorded.
• wtOptions (Object, optional) – WebTransport configuration settings (default: {}).
• mimeType (string, optional) – MIME type for recording (default: "video/webm").

Methods

start(timeslice = 1000)

Initializes WebTransport and starts recording.

| Parameter | Type | Default | Description | |------------|--------|---------|-------------| | timeslice | number | 1000 | Time interval (ms) for collecting data chunks |

Returns: Promise<void>

stop()

Stops recording and closes the WebTransport session.

Returns: Promise<void>

getRecordedBlob()

Returns the recorded media as a Blob.

Returns: Blob

Throws an error if no recorded data is available.

cleanup()

Cleans up resources and resets the instance.

convertBase64Digest(base64Digest)

Converts a Base64-encoded server digest into a format compatible with WebTransport.

Parameters:

• base64Digest (string) – Base64-encoded SHA-256 digest.

Returns: Uint8Array

Throws an error if the input is not a valid Base64 string.

const digest = "c29tZUJhc2U2NERpZ2VzdA=="; // Example Base64 digest
const uint8Array = WTRecorder.convertBase64Digest(digest);
console.log(uint8Array);

Example Implementation

import { WTRecorder } from '@mastashake08/wt-recorder';

(async () => {
  try {
    const stream = await navigator.mediaDevices.getUserMedia({ video: true, audio: true });

    const wtOptions = { allowPooling: true };
    const recorder = new WTRecorder("https://your-server.com/webtransport", stream, wtOptions);

    await recorder.start(500);

    setTimeout(async () => {
      await recorder.stop();
      const recordedBlob = recorder.getRecordedBlob();
      console.log("Recorded Blob:", recordedBlob);
    }, 5000);
  } catch (error) {
    console.error("WTRecorder Error:", error);
  }
})();

Error Handling

WTRecorder includes robust error handling:

• Validates input parameters (server URL, media stream).
• Logs WebTransport initialization failures.
• Handles errors from MediaRecorder and stops the recording if necessary.
• Ensures cleanup after failures.
• Throws explicit errors for invalid input formats.

License

This project is licensed under the MIT License.

Contributions

Contributions are welcome. Submit issues or pull requests for improvements and feature requests.