How to convert a unix timestamp field in views
You can use hook_views_pre_render to change the output of your field..


  This hook is called right before the render process. The query has
  been executed, and the pre_render() phase has already happened for
  handlers, so all data should be available.
  
  Adding output to the view can be accomplished by placing text on
  $view->attachment_before and $view->attachment_after. Altering the
  content can be achieved by editing the items of $view->result.


function MYMODULE_views_pre_render(&amp;$view) {

   if ($view-&gt;name=='viewyouarelookingfor') {

      // do whatever you want

   }

 }