Custom video source for WebRTC on Android

Custom Video Source for WebRTC on Android

WebRTC, or Web Real-Time Communication, allows real-time communication between web browsers. On Android, you can leverage WebRTC to build powerful video conferencing, live streaming, and other communication applications. While WebRTC usually uses the default camera, you can extend its functionality by providing a custom video source.

Why Use a Custom Video Source?

There are several reasons why you might want to use a custom video source in your Android WebRTC application:

• Process external video streams: Decode and stream video from sources other than the device’s camera, like files, network streams, or screen captures.
• Manipulate video frames: Apply filters, effects, or other transformations to the video stream before sending it.
• Optimize video encoding: Control the encoding process and customize settings for specific scenarios.
• Integrate with existing camera APIs: Work with specialized camera libraries that offer features beyond the default WebRTC camera.

Steps to Create a Custom Video Source

1. Create a Custom Video Source Class

import org.webrtc.VideoSource;
import org.webrtc.VideoTrack;

public class MyCustomVideoSource implements VideoSource {

    // ... (Implementation of VideoSource interface methods)

    @Override
    public VideoTrack createTrack(String id) {
        // ... (Create and return a VideoTrack using your custom video source)
    }
}

2. Implement VideoSource Interface Methods

• createTrack(String id): This method is called to create a VideoTrack from your custom video source. You need to create a VideoTrack using your custom video data and return it.
• dispose(): Release resources associated with your custom video source.
• getStats(): Return statistics about the video source.

3. Create a VideoTrack

import org.webrtc.VideoTrack;

public class MyCustomVideoTrack extends VideoTrack {

    // ... (Constructor and methods for your custom VideoTrack)

    @Override
    public void onFrame(VideoFrame frame) {
        // ... (Process the incoming video frame from your custom source)
    }
}

4. Integrate into WebRTC

import org.webrtc.PeerConnectionFactory;
import org.webrtc.VideoTrack;

// ...

// Create a PeerConnectionFactory
PeerConnectionFactory factory = PeerConnectionFactory.getInstance();

// Create your custom video source
MyCustomVideoSource videoSource = new MyCustomVideoSource();

// Create a VideoTrack
VideoTrack track = videoSource.createTrack("myCustomVideoTrack");

// Add the track to your MediaStream
MediaStream stream = factory.createLocalMediaStream("myStream");
stream.addTrack(track);

// Use the MediaStream for WebRTC communication

Example: Using a MediaRecorder

Here’s a simple example of how you can use a MediaRecorder to create a custom video source for WebRTC:

Code

import android.media.MediaRecorder;
import android.view.SurfaceView;
import org.webrtc.VideoFrame;
import org.webrtc.VideoSource;
import org.webrtc.VideoTrack;

public class MediaRecorderVideoSource implements VideoSource {

    private MediaRecorder mediaRecorder;
    private SurfaceView surfaceView;

    public MediaRecorderVideoSource(SurfaceView surfaceView) {
        this.surfaceView = surfaceView;
    }

    @Override
    public VideoTrack createTrack(String id) {
        return new MyCustomVideoTrack(this);
    }

    @Override
    public void dispose() {
        if (mediaRecorder != null) {
            mediaRecorder.stop();
            mediaRecorder.release();
            mediaRecorder = null;
        }
    }

    @Override
    public Stats getStats() {
        // ... (Implement if needed)
    }

    // ... (Implement methods to start and stop recording)

    private class MyCustomVideoTrack extends VideoTrack {

        private MediaRecorderVideoSource videoSource;

        public MyCustomVideoTrack(MediaRecorderVideoSource videoSource) {
            super("myCustomVideoTrack");
            this.videoSource = videoSource;
        }

        @Override
        public void onFrame(VideoFrame frame) {
            // ... (Process the incoming video frame from the MediaRecorder)
        }
    }
}

Explanation

• The MediaRecorderVideoSource class implements the VideoSource interface.
• It creates a MediaRecorder object to capture video from a SurfaceView.
• The MyCustomVideoTrack class handles incoming video frames from the MediaRecorder.
• The onFrame() method of MyCustomVideoTrack processes the video frames and provides them to WebRTC.

Considerations

• Performance: Custom video sources can impact performance, especially if you are performing complex processing on video frames.
• Synchronization: Ensure that your video source is synchronized with WebRTC’s timing mechanisms.
• Memory Management: Release resources properly to avoid memory leaks.
• Code Complexity: Creating custom video sources can be more complex than using the default camera.

Conclusion

By creating a custom video source for WebRTC on Android, you can enhance your communication applications with more flexibility and control. This allows you to integrate with various video sources, manipulate video streams, and optimize for specific use cases. Just remember to consider performance and memory management when designing your custom video source.