[MEncoder-users] problem with jvc SA divx reader

[Luigi]

i have  a problem with my jvc stand alone divx reader. i have converted a movie with mencoder and codec mpeg4 of libavcodec.
if i see movie with xine the result is good, while if i see it with the reader in object i see two black border at top and bottom of movie.
the problem is the movie has aspect ratio of 4/3 as my tv, therefore these two border don't must exist.
 i resize movie to 640x480 (4/3).
maybe is it a codec problem?
or maybe is it a reader problem?
perhaps i must use official divx codec....

thanks in advice
Luigi
NB: excuse fo my english.