I have a client who wants 16:9 1290X720 and 16:9 720X480 both videos need to be compressed to mpg4 from a 1920X1080 video. When I compress the 480 video I am using 853X480 with a 16:9 anamorphic NTSC setting (which should make 720X480), however when I do that setting the video is compressed looking more strecthed compared to my 1280X720 mpg4 video.
Here is how it looks
You're doubling up on the stretch. 720x480 with 16x9 PAR = 853x480 in square pixel land. So encode for either 853x480 square pixels, or 720x480 with 16x9 pixel aspect. What you write above is encoding 853x480 with 16x9 pixel aspect - this is doubling the stretch.