Convert Video on Linux for Nokia N97

you can save different configurations as profiles for mencoder use.

1. create configuration file ~/.mplayer/mencoder.conf if there is not.
if in windows, the file should be put in the same folder with config and input.conf

2. edit mencoder.conf

[n97]
profile-desc="MPEG4/AAC"
vf=scale=640:-3,harddup
ovc=lavc=yes
oac=lavc=yes
lavcopts=aglobal=1:vglobal=1:acodec=libfaac:vcodec=mpeg4:abitrate=96:vbitrate=896
af=lavcresample=44100
ofps=25
of=lavf=yes
lavfopts=format=mp4

[profile2]
..
..

the quality of video from the above setting is good enough. but you still can adjust them in the suitable range
abitrate: 96 ~ 192
vbitrate: 896 ~ 4000

3. specify which profile to use

mencoder -profile n97 -o output.mp4 input_file