Can I add some driver to my mp4?

[umbyfish]

i've a PMP mp4 player, it does a lot of things, it's like a psp.
it reads only asf file, and they're very large! can i add some codecs in order to read more formats like .wmv or .avi?
is there a program to better convert asf file???
help!!!!!!!!!

[maucor2]

you can use .mp4 format, it is better because is smaller than the asf and it has better quality