Change MediaRecorder frame rate

The only one possible way to change frame rate in video produced by MediaRecorder is to define video constraints when you call getUserMedia or getDisplayMedia.

MediaRecorder itself can't control actual frame rate, it just records at same frame rate that provides MediaStream.

Important Note from MediaRecorder docs at MDN:

Video resolution, frame rate and similar settings are specified as constraints when calling getUserMedia(), not here in the MediaRecorder API.

Example code:

const webcamStream = await navigator.mediaDevices.getUserMedia({
  video: {
    frameRate: {
      min: 24,  // very important to define min value here
      ideal: 24,
      max: 25,
    },
  },
});