function resizeBackgroundImage(){
  // get image container size
  var scale = Math.max( windowHeight/streetImgHeight , windowWidth/streetImgWidth );
  var width = scale * streetImgWidth , height = scale * streetImgHeight;
  var left = (windowWidth-width)/2, top = (windowHeight-height)/2;
  $$videoContainer
    .width(width).height(height)
    .css('position','fixed')
    .css('left',left+'px')
    .css('top',top+'px');
  }