Hi people, i hope someone can help me

I have a mp4 player, and i'm using AMV COnversion tool 3.68
When a choose resolution 128X128 the video converted doesn't appears full width...a little part of the laterals are missing, and when I watch this on the mp4 player, there are two black strip on the sides (left, right)...

the hight are ok...just the widht of the video are missing parts

Someone knows if it is a problem of conversion tool ?? or of the resolution of video ??