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Overview

Record video from WebRTC/MediaStream sources:
  • Video conferencing recordings
  • Screen recordings
  • Camera feeds
  • Live streaming archives
This guide shows the encoding side. For capturing MediaStream data in Node.js, you’ll need platform-specific capture tools or receive data from a browser.

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Basic MediaStream Recording

const { VideoEncoder, VideoFrame } = require('node-webcodecs');

async function recordMediaStream(mediaStreamFrames) {
  const chunks = [];

  const encoder = new VideoEncoder({
    output: (chunk) => {
      const buffer = Buffer.alloc(chunk.byteLength);
      chunk.copyTo(buffer);
      chunks.push(buffer);
    },
    error: (err) => { throw err; }
  });

  encoder.configure({
    codec: 'avc1.42E01E',
    width: 1920,
    height: 1080,
    bitrate: 5_000_000,
    framerate: 30,
    latencyMode: 'realtime'  // Low latency for live recording
  });

  for (const frameData of mediaStreamFrames) {
    const frame = new VideoFrame(frameData.data, {
      format: 'RGBA',
      codedWidth: 1920,
      codedHeight: 1080,
      timestamp: frameData.timestamp
    });

    encoder.encode(frame);
    frame.close();
  }

  await encoder.flush();
  encoder.close();

  return Buffer.concat(chunks);
}

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Real-Time Encoding

For live streams, use real-time encoding mode: 
const encoder = new VideoEncoder({
  output: (chunk) => {
    // Send to live stream server
    streamServer.send(chunk);
  },
  error: (err) => { throw err; }
});

encoder.configure({
  codec: 'avc1.42E01E',
  width: 1280,
  height: 720,
  bitrate: 3_000_000,
  framerate: 30,
  latencyMode: 'realtime',  // ← Optimize for low latency
  bitrateMode: 'constant'   // ← CBR for streaming
});

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Best Practices

  • Use realtime latency mode
  • Use constant bitrate (CBR)
  • Handle dropped frames gracefully
  • Buffer output to handle network jitter

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Next Steps

Transcoding

Convert recorded streams

Examples

More examples