need help playing vids

What are the exact specs does video file need to have to be able to play on a psp? Do they need to have specific resolutions, file name, or location? I know they need to be mp4 but if I try to play mp4 videos i get from from video google and some other files they wont play. The only way i can get videos to work is by using PSP Video Express to convert non mp4 files to mp4 and transfering it onto my psp but the program sucks becasue the timing between the audio and video is off always. Oh yeah and i put the videos in \MP_ROOT\100MNV01 and renamed it M4V#####.MP4 so, does anybody know whay they dont play? maybe my psp is messed up? thanks

it depends what resolution ur using, u are missing one more folder in the mp_root. that one is 100ANV01. I would suggest using 3GP converter. Sometimes the audio is off, but not all the time. I have experienced that. Your PSP video express should rename it not you. If u need anymore help just ask. I will give u a link to website that explains it step by step.

Try PSP Video 9 it works great.