[mythtv-users] trouble with ffmpeg and mpeg4 codec

[ffrr]

I am using ffmpeg (and mencoder) from the command line to convert video 
to a small format for my PDA (as I mentioned in another thread).  I 
decided to try a different codec from the default in ffmpeg, in fact I 
am trying mpeg4.  The command line I am using is

ffmpeg -i infile -vcodec mpeg4 -b 200 -ab 96 -s 480x270 outfile


and ffmpeg accepts that.  It starts converting, but if I try playing the file, gxine tells me it is a 1x7 mpeg (libmpeg2) (and shows no picture).

I uninstalled, then reinstalled ffmpeg using urpmi.  The rpm it is installing is ffmpeg-0.4.9-0.pre1.5mdk.i586.rpm.

Is this version broken (if so how can I get one that's not)?  
Any other ideas?