What is WSS (Wide Screen Signaling) and what is the difference between 16:9 (16×9) and 4:3 (4×3) aspect ratios?

Wide screen signaling (WSS) is a method that allows the transmission signal to carry information about itself, specifically, what aspect ratio (16:9 or 4:3) to display the content at. The WSS, if present in the transmission, allows displays (monitors/TVs) that support it, to change the aspect ratio dynamically on the fly.

For more information on these topics, please refer to the following article:

http://www.amcro.co.uk/widescr.htm

For information on AVN encoders and WSS, please refer to this FAQ.