gnome-mplayer does not play videos in the correct aspect ratio

When I play via mplayer the resolution is perfect. It completely fullscreen. The playback on the other hand is terrible. It freezes and goes in slow motion. So is there a way I can get the resolution and playback to work in gnome-mplayer?

gnome-mplayer does not play videos in the correct aspect ratio

When I try to watch a video it does not cover the entire screen. Sometimes it is a small box playing in the center when it is full screen other times there are large chunks of black space on both sides of the monitor.