[as I changed to a different avi, the resolution that applies to my information below was 608x256 for the avi file]
Thanks again to FakeOutdoorsman for the -vframes suggestion. I also discovered that I could do -ss and -t options to compile a specific segment, this way I avoid the opening credits and get straight to the movie at some specific place. For example, to view 60 seconds of movie starting at four minutes into the movie do:
After testing, I settled on:
ffmpeg ... -ss 00:4:00:00 -t 60 ... out.mpg
I basically offset the the standard NTSC DVD size (720x480) by the number of pixels in my padding (480-20-20=440) for a 720x440 size. This worked perfectly for my dvd player on the computer but was a little off on the final burn and on my DVD machine (explained later below).
ffmpeg -y -i ScroogeFinney.avi -target ntsc-dvd -s 720x440 -padbottom 20 -padtop 20 out.mpg
After the ffmpeg conversion, when I did dvdauthor, it gave me a mass of warnings about frame rate being off or something, and then nothing seemed to be happening but after a bit, it finished up doing it's job. Then I did the final step of the dvdauthor as outlined in the previous post, and then I did mkisofs to make an iso, and then I burned it.
It almost worked. The adjustment made automatically by dvdauthor made the images automatically cropped left and right on the DVD machine, and the images were still only slightly stretchy, so I think my padding should have been somewhere between 30 and 40 pixels. I'll give it one more shot at around 34 or 36 padding and see how that finally translates. It should be just fine. Actually, the final DVD was watchable, I mean, my wife, who's pretty picky, said the stretching was only slight enough I didn't need to try again, but since this is my favorite movie, I want to get it more precise.