getUserMedia() and webRTC, modify the buffer before sending

General
1

I’ve tried researching this on my own, but fell short.

Let’s say I use getUserMedia() and webRTC to make video calls. Is it possible to hook between the getUserMedia() and webRTC and modify the buffer before it is sent?

Simplest example: Sender base64 encodes the buffer before sending it, receiver decodes it and sending and receiving software is none the wiser that that is happening in the background?

2

Yes, it’s possible to hook between getUserMedia() and WebRTC to modify the buffer before it is sent. This technique is often referred to as media manipulation or media tampering.

Here’s a simplified example of how you could base64 encode the buffer before sending it:

JavaScript

navigator.mediaDevices.getUserMedia({ video: true })
  .then(stream => {
    const videoTrack = stream.getVideoTracks()[0];
    const videoElement = document.getElementById('video');
    videoElement.srcObject = stream;

    // Create a MediaRecorder to capture the video stream
    const recorder = new MediaRecorder(stream);

    recorder.ondataavailable = (event) => {
      const blob = event.data;
      const reader = new FileReader();

      reader.onloadend    1.  github.com github.com = () => {
        const base64Data = reader.result;

        // Send the base64 data to the receiver
        // ...

        // Optionally, decode the base64 data and create a new blob
        const decodedBlob = new Blob([atob(base64Data)], { type: blob.type });

        // Send the decoded blob to WebRTC
        // ...
      };

      reader.readAsDataURL(blob);
    };

    recorder.start();
  })
  .catch(error => {
    console.error('Error accessing getUserMedia:', error);
  });

In this example:

  1. We get the video stream using getUserMedia().
  2. We create a MediaRecorder to capture the video frames.
  3. When a new data chunk is available, we read it as a data URL using FileReader.
  4. We base64 encode the data URL.
  5. We send the base64 data to the receiver.
  6. Optionally, we decode the base64 data and create a new blob to send to WebRTC.

Note that this is a simplified example and there are many other factors to consider when manipulating media streams, such as:

  • Performance: Encoding and decoding media can be computationally expensive, especially for high-resolution video.
  • Compatibility: Different browsers and devices may have different capabilities and limitations for media manipulation.
  • Security: Manipulating media streams can raise security concerns, as it can be used to intercept or modify data.

If you are considering using media manipulation in your application, it is important to carefully evaluate the trade-offs and ensure that it is done in a secure and responsible manner.