From: Multiplex USA on
There have been many posts about the 16:9 Formats Aspect Ratio. If you want
to read more about how A.C.E. pros do it and other professional moviemaking
tips, go to the ACE website at
http://www.ace-filmeditors.org/newace/downloads.html and if you want the
official spiel on aspect ratios, select "History Of Square Vs Wide Screen"
from that page.

http://www.ace-filmeditors.org/newace/downloads.html