I’m building a retiming tool for videos on YouTube and other websites, and finding the frame rate of the video element is necessary for frame-by-frame seeking and rounding reasons.

The way I’m doing it so far is by using requestVideoFrameCallback() and finding the smallest difference between two frame times: (sorry for bad formatting, I’m on mobile)

var v = document.querySelector(“video”)
var c = 0; // time of last frame 
var framelength = 1; // length of one frame 
var fps;
  function check(t, m) {
      var diff = Math.abs(m.mediaTime - c); // difference between this frame and the last
      if (diff && diff < framelength) {
        framelength = diff;
    fps = Math.round( 1 / framelength)
      }
      c = m.mediaTime;
      v.requestVideoFrameCallback(check);
    }
    v.requestVideoFrameCallback(check);

However, there are sometimes rounding issues due to the mediaTime having only 3 decimal places, so is there a better way to find the FPS with JavaScript?