Question

How can I insert ads on html5 video tag before the main video plays? Is there any open source tools to make this easier? Is there any reference that can guide me there?

It is working with this code:

<script type="text/javascript">
   // listener function changes src
   function myNewSrc() {
      var myVideo = document.getElementsByTagName('video')[0];
      myVideo.src="../main.webm";
      myVideo.load();
      myVideo.play();
    }

   // function adds listener function to ended event -->

    function myAddListener(){
     var myVideo = document.getElementsByTagName('video')[0];
     myVideo.addEventListener('ended',myNewSrc,false);
    }
</script>

but I can’t when it play the second one. It shows the poster. How do I get rid of the poster?

Answer 1

This is a quick off the cuff start of a solution that should at least point you in the right direction. This gives you a singleton with an init method that when called sets up a preroll on a particular video element.

var adManager = function () {
    var vid = document.getElementById("myVid"),
        adSrc = "videos/epic_rap_battles_of_history_16_adolf_hitler_vs_darth_vader_2_1280x720.mp4",
        src;

    var adEnded = function () {
        vid.removeEventListener("ended", adEnded, false);
        vid.src = src;
        vid.load();
        vid.play();
    };

    return {
        init: function () {
            src = vid.src;
            vid.src = adSrc;
            vid.load();
            vid.addEventListener("ended", adEnded, false);
        }
    };
}();

There are a number of things that aren’t covered here, though. For instance, if you set the init method to be called when you start playing the video, you’ll need to keep a flag that indicates whether there’s an ad playing so that the play handler won’t do anything when you’re transitioning from the ad to the content (which requires a “play” event after the load() call in order to get the seamless playback).

We use something similar in our video playing project, and most of the video ad services out there do something like this for HTML based video playback (as opposed to Flash video playback).

It’s relatively straightforward, but you just have to make sure to keep track of when event callbacks should be fired and when to add and remove those callbacks.

Another thing to consider is the unreliability of the “ended” event. I haven’t yet figured out when and on which platforms it consistently fires, but it’s a fairly well known problem. A possible solution is to use “timeupdate” instead and test whether the “currentTime” property is somewhere around a second less than the “duration” property so you know you’re right at the end of the video.