How does GSpot calculate "Recommended display size" I've got a video and I thought it's size was 640x480 and this is shown on GSpot.

However also in the container section of GSpot it is saying

 Recommended Display Size: 853 x 480


does anyone know where it get's this from?

1) If it is calculated what from?

2) If it is a property of the file while isn't it the same as the width x height?
I don't know what tags or fields are present in a .MP4 file, but something is flagging the file as having a 16:9 'display aspect ratio' (shown as "dar" in GSpot), while the 'pixel aspect ratio' (par) is 4:3. 

((480 * 16) / 9) = 853