How to create dynamic json for jplayer dynamic media file type

        var jsonmedia = {};

        jsonmedia[mediatype] = mediafile;
        jsonmedia["poster"] = "/pccas/Uploads/AttachedDoc/Big_Buck_Bunny_Trailer_480x270.png";

        $("#jquery_jplayer_1").jPlayer({
                ready: function () {
                    $(this).jPlayer("setMedia", jsonmedia
                    );
                },
                swfPath: "/js",
                supplied: "m4v, ogv,m4a,mp3,mp4",
                size: {
                    width: "640px",
                    height: "360px",
                    cssClass: "jp-video-360p"
                },
            });