Question about video resolution

[teqnilogik]

I'm using TMPGEnc Xpress to encode some DVD movies to DivX. I have noticed that TMPGEnc will resize the movie to fit whatever resolution I choose, however, it is letterboxing the movie. Programs such as AutoGK will crop and resize the movie and change the resolution so there is no letterboxing done. It appears to me that TMPGEnc resizes the movie to fit into the chosen resolution such as 720x480 and then just adds black bars to letterbox it and keep the correct aspect ratio. Would I achieve better quality if I crop the movie manually, calculate the correct resolution for the movie using a program such as Aspect, and then resize the movie to the correct resolution using TMPGEnc? The way it is being done now, I assume that TMPGEnc is encoding the movie with the black bars on the top and bottom and I believe that would use unnecessary bits and possibly degrade quality. Is that correct?

[CWR03]

It depends mainly on your purpose for the files whether you should encode them at the proper AR to begin with or allow the bars to be added, but you will likely run into problems with playback doing it the way you are more than you'll lose quality.