Video Aspect Ratio

The term Aspect Ratio refers to the width of a picture (or screen) in relation to its height. Ratios are expressed in the form "width x height". For example, a 4x3 ratio means the picture is 4 units wide by 3 units high. Alternatively a colon may be used (e.g. 4:3 or 16:9) or a ratio to the number 1 (e.g. 1.33:1 or 1.78:1). Note that the actual physical size of the picture is irrelevant — aspect ratio refers only to the relationship between width and height.