Manoj Damor

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How to Convert WebM to MP4 with WebRTC and PHP

3 min read

Bridging Formats: Converting WebM to MP4 with WebRTC and PHP

In the fast-paced realm of web development, WebRTC (Web Real-Time Communication) has emerged as a transformative technology, empowering developers to build real-time communication applications directly within web browsers. However, one of the common challenges faced is dealing with media format compatibility, especially when it comes to converting the default WebM format to the more universally supported MP4 format. In this comprehensive guide, we’ll explore the integration of WebRTC, PHP, and FFmpeg to seamlessly convert WebM to MP4, ensuring broader compatibility and enhancing the versatility of your real-time communication applications.

Understanding the WebRTC Landscape

WebRTC is a set of technologies that enables real-time communication directly between web browsers. It facilitates peer-to-peer communication for audio, video, and data sharing without the need for plugins or external applications. While WebRTC provides powerful tools for capturing and recording media, it defaults to the WebM format, which may pose compatibility challenges with certain platforms and applications that prefer the MP4 format.

The Role of FFmpeg in Media Conversion

FFmpeg is a powerful, open-source multimedia processing tool that plays a crucial role in handling audio and video processing tasks. In the context of this guide, FFmpeg will be utilized to convert WebM to MP4. Leveraging FFmpeg within a PHP environment allows for server-side processing of media files, providing greater flexibility and control over the conversion process.


Before delving into the conversion process, ensure the following components are in place:

  1. WebRTC Application: Have a functioning WebRTC application set up for capturing and recording audio or video.
  2. FFmpeg Library: Download and set up the FFmpeg library on your server. This will enable PHP scripts to interact with FFmpeg for media processing.
  3. PHP Environment: Ensure your server has PHP installed, and you have the necessary permissions to execute server-side scripts.

Step-by-Step Guide to WebM to MP4 Conversion

Step 1: Capture and Record Media with WebRTC

Begin by capturing and recording media within your WebRTC application. Use the getUserMedia API for user media access and the MediaRecorder API for recording.

navigator.mediaDevices.getUserMedia({ video: true })
    .then((stream) => {
        const mediaRecorder = new MediaRecorder(stream);
        let recordedChunks = [];

        mediaRecorder.ondataavailable = (event) => {
            if ( > 0) {

        mediaRecorder.onstop = () => {
            // Perform conversion after recording is complete

        // Start recording

        // Stop recording after a certain duration or user interaction
        setTimeout(() => {
        }, 10000);  // Stop after 10 seconds (adjust as needed)
    .catch((error) => {
        console.error('Error accessing user media:', error);

Step 2: Send WebM Data to PHP Server

Once the WebM recording is complete, send the recorded data to the PHP server for conversion. This might involve making an AJAX request or using a WebSocket for real-time communication.

function convertWebMToMP4(recordedChunks) {
    const endpoint = 'convert.php';

    // Convert Blob to base64 for transmission
    const blob = new Blob(recordedChunks, { type: 'video/webm' });
    const reader = new FileReader();

    reader.onloadend = () => {
        const base64data = reader.result.split(',')[1];
        // Send base64 data to PHP server


function sendDataToServer(base64data) {
    // AJAX or WebSocket communication to send data to PHP server
    // Implementation depends on your server communication strategy

Step 3: PHP Server-Side Conversion with FFmpeg

On the PHP server, handle the incoming WebM data and use FFmpeg for the conversion to MP4. Ensure that you have the FFmpeg library included in your PHP script.

$base64data = $_POST['data'];

// Convert base64 to binary
$binaryData = base64_decode($base64data);

// Save binary data to a temporary WebM file
file_put_contents('input.webm', $binaryData);

// Execute FFmpeg command for conversion
exec('ffmpeg -i input.webm -c:v libx264 -c:a aac -strict experimental output.mp4');

// Read the converted MP4 file
$convertedData = file_get_contents('output.mp4');

// Send the converted MP4 data back to the client
echo base64_encode($convertedData);

Step 4: Receive and Use the Converted MP4 Data

Back on the client side, receive the converted MP4 data from the PHP server and use it as needed. This might involve displaying the video to the user or saving it for future use.

// AJAX or WebSocket communication to receive and use the converted MP4 data
// Implementation depends on your server communication strategy


Congratulations! You’ve successfully integrated WebRTC, PHP, and FFmpeg to convert WebM to MP4 seamlessly. This approach ensures broader compatibility with various platforms and players, enhancing the overall usability of your real-time communication applications. As you implement this solution, consider additional aspects such as error handling, security measures, and optimizing the conversion process for different use cases. Happy coding!

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