rtMedia Pro - uploader.php adding custom data field

Hi !

I have followed this topic to add a custom data field in uploader and to save and display result in the lightbox.

I have added the codes below but I can't retrieve my custom data.
Perhaps that I need to add another function in php to be able to retrieve my custom data, or that I should modify the js file?

Thank you very much for your help !

In functions.php:

    function custom_data() {
            global $rtmedia_media;
            ?>  <div> city :<input class="city" id="city" type="text" name="city" value="" /> </div>
            <?php
            }
    add_action('rtmedia_uploader_before_start_upload_button', 'custom_data');

And in my js file:

(function($) {
"use strict";
$(document).ready(function() {
    rtMediaHook.register(
        'rtmedia_js_after_file_upload',
        function (args ) {
			
var donnees = $(this).serialize();     
$.ajax({
       type: "POST",
       url: "../../../plugins/buddypress-media/templates/media/media-single.php",
       data: donnees,
       success : function(data){
       $("#texte_a_inserer").html(data);
        }
	});
		});
});
})(jQuery);