rounded corners on html5 video

It works in Firefox as long as you set the appropriate 180px height for the 320px width video (16:9 aspect ratio) - otherwise the curved borders aren't visible because they're outside the frame of the video.

There are some outstanding bugs in WebKit to do with it clipping content in concert with border-radius, like this one or this one specifically about the video element.

Try this. It should work.

-webkit-mask: url(mypath/mask.png);

where the mask.png should be a rounded corner shape. Did this quick with a circle. [url removed]

This can be done with canvas and JavaScript at least (Introduction how to manipulate video frame data with canvas). You basically draw a new canvas, apply the video frame data there, then clip the rounded corners off. I created this quickly, so didn't check whether the anti-aliasing could have been improved, but at least it does the rounding. Performance wise, you can imagine this isn't really as good as applying CSS or something, but it should work on all canvas supported browsers at least.

   var video = document.getElementById("video");
    var c1 = document.getElementById("roundy");
    var ctx = c1.getContext("2d");

    video.addEventListener("play", function() {
        timerCallback();
      }, false);

var timerCallback = function() {
    if (video.paused || video.ended) {
      return;
    }
    computeFrame();

    setTimeout(function () {
        timerCallback();
      }, 0);
  };

var computeFrame = function() {

        var w = 480;
    var h = 320;
    var r = 20;
    ctx.clearRect(0,0,w,h);





    ctx.globalCompositeOperation = 'destination-atop';

   ctx.fillStyle = "#09f";
  roundRect(ctx, 0,0,w,h,r,true,false);
      ctx.drawImage(video, 0, 0, w, h);



    return;
  }
    // http://js-bits.blogspot.com/2010/07/canvas-rounded-corner-rectangles.html

    function roundRect(ctx, x, y, width, height, radius, fill, stroke) {
  if (typeof stroke == "undefined" ) {
    stroke = true;
  }
  if (typeof radius === "undefined") {
    radius = 5;
  }
  ctx.beginPath();
  ctx.moveTo(x + radius, y);
  ctx.lineTo(x + width - radius, y);
  ctx.quadraticCurveTo(x + width, y, x + width, y + radius);
  ctx.lineTo(x + width, y + height - radius);
  ctx.quadraticCurveTo(x + width, y + height, x + width - radius, y + height);
  ctx.lineTo(x + radius, y + height);
  ctx.quadraticCurveTo(x, y + height, x, y + height - radius);
  ctx.lineTo(x, y + radius);