I have a film but its an mp4 file. I have dvx codec etc, but not having any luck playing it. Is there any free software I can use to convert the file?

Thanks

klite codec pack includes classic media player andhas played everything I have chucked at it:

http://www.free-codecs.com/download/K_lite_codec_pack.htm

I usually use vlc (http://www.videolan.org/vlc/)

Many thanks. Downloaded the free codecs and the movie playing with no problems.