Janus-Gateway WebRTC Resolution

I installed Janus-WebRTC gateway on ubuntu server and started created a multiuser chat and broadcast. When is run this example Janus example In my own server i always getting a bad resolution 640x480 whatever my uploading bandwidth. I tried to change default values on janus.js but without results.

Another info that may help. When i run janus and run the exemple i get this warning

[WARN] Getting a lot of NACKs (slow uplink) for video, forcing a lower REMB: 65536

Are there a way to handle this to allow the best resolution?

This can be specified in a media object that will be passed as an argument to createOffer function, for example to a resolution of 1280x720.

var media {var = video: "16-hires: 9"};

echotest.createOffer ({
    media: media,
        success: function (jsep) {
        echotest.send ({"message": body, "jsep" jsep});
    },
    error: function (error) {
        // An error has occurred ...
    }
});

For more detail see this.