When/How should I use an authentication to check if the user can see a protected content?

Question

I am building a client side player(using videojs) which takes an mpd (protected) and play it. I would like to ask When/How I should make an authentication to check If the user that request a license from a license server(widevine,playready) is authorized to see the protected content.

player.ready(function() {
    this.src({
        src:'http://yt-dash-mse-test.commondatastorage.googleapis.com/media/car-20120827-manifest.mpd',
        type: 'application/dash+xml'
    });
});

Answer 1

Typically you would authenticate the user even before showing the user the video playback page. But in addition to that, it is common to have some sort of authentication mechanism in your communication with the DRM License Server of choice. How to do this, depends on whether you are using a service provider that have this already defined, or whether you are planning to implement the license server yourself.