You don't need any filter in order to achieve that, just make a default src:

<img ng-src="{{('/media/upload/' + user.id + '.jpg')}}" src="/media/upload/default.jpeg" height="80px" width="80px"/>

The ngSrc directive whould replace the source only if available

In order to test all possible extensions, I would write a directive:

app.directive('multiSrc', function($q) {
  return {
    restrict: 'A',
    scope: { user: '=' },
    link: function(scope, element) {

      console.log(scope.user);

      var image = new Image();
      var _ext = ['jpg', 'jpeg', 'png', 'gif'];
      function _loadExt(index) {
        if(index >= _ext.length) {
          return;
        }
        _tryLoading(_ext[index])
        .then(function(successImage) {
          element[0].src = successImage.src;
        }, function() {
         return _loadExt(index + 1);
        });
      }
      function _tryLoading(extension) {
        var _defer = $q.defer();
        image.src = '/media/upload/' + scope.user.id + '.' + extension;
        image.onerror = function() {
          _defer.reject();
        };
        image.onload = function() {
          _defer.resolve(angular.copy(image));
        }
        return _defer.promise;
      }
      return _loadExt(0);
   }
 };
});

Edit

This is showing one way to implement it. But it IS NOT best practice at all.

The way this should be done, is when the user upload an image, save the path in the database (within the user object usually), then just request the registered path.