Aspect ratio for VCD/SVCD/DVD

There are four aspect ratios defined for the mpeg standard
  1. 1:1
  2. 4:3
  3. 16:9
  4. 2.21:1
If you want to create a VCD/SVCD/DVD and the aspect ratio of the source video is not one of the four values permitted, you need to change the aspect ratio of the source video or the encoded video will be distorted.
There are two ways to change the aspect ratio of a movie: expand or crop.
Imagine your source video is 576x288 (aspect ratio 2:1) and you want to create a 16/9 NTSC DVD (720x480).
If you are expanding the video you have to add 36 horizontal black lines (576x324 aspect 16:9) and scale to 720x480 (NTSC DVD).
If you are cropping the video you have to cut 64 vertical lines (512x288 aspect 16:9) and scale to 720x480 (NTSC DVD).
If you expand the video, all the original video will be visible on the screen, but part of the screen will be black.
If you crop the video, the complete screen will be used for the video, but you will loose the borders of the original video.
In encode2mpeg add:
-mpegfixaspect expand
if you intend to expand the source video, or add
-mpegfixaspect crop
if you intend to crop the source video.