My propose is draw video frame to canvas and draw thing else on canvas. I have test it success in video link without Widevine.

var canvas = document.getElementById("canvasDraw");
canvas.style.width = 1280;
canvas.style.height = 720;

var context = canvas.getContext('2d');

var video = document.getElementById('video');

function draw() {
  context.drawImage(video, 0, 0, 1280, 720);
  setTimeout(draw, 1000 / 30);
}
video.onplay = function () {
  setTimeout(draw, 1000 / 30);
}

But when I using widevine drm the frame came out is black but the audio is still playing.

Can someone help me with this ?

This is the widevine link I get from shaka-player demo

https://storage.googleapis.com/shaka-demo-assets/sintel-widevine/dash.mpd