Your mp4 needs to be modified before it will work...

right, so you finally have your mp4 file thats been lovingly hand crafted with x264. We are almost there, one (well one and half...) more steps to getting that little punk finally onto your PSP.

For whatever reason, sony decided to mess around with the standards and make the PSP video files different to normal. This could have been a major issue, but as usual, some smart folk managed to sort it out. Sadly I dont know who the original author was, but of course many thanks to them and also thanks to qyqgpower a kind user over on doom9 who recompiled atomachanger to remove the 29fps settings. Now it takes the FPS from the file, so 24fps etc. isnt an issue. A god send to use PAL folk of course, and those who have any HD stuff to convert from 23.97.

Anyway, its a command line tool but personally I just run it from a batch file. The file, atom.bat is included in the zip on the front page. There is nothing bad in the batch file, as you will see when you open it in notepage. Now, in the zip you will find atomchanger and the ini file it uses, AtomAVC.ini. Extract all 3 files into a folder, for ease of use, copy your mp4 into the same folder. Then open atom.bat in notepad (right click, edit) and you will see:

start /belownormal /b /w ATOMChanger.exe hthg.mp4 c:\MAQ00432.MP4 AtomAVC.ini

in this case, my mp4 is called hthg.mp4 which wasnt very smart as the PSP will use this name as the title. Anyway, edit the bat file so that the mp4 is the same name as your file and also the output isnt going to be an issue. you can change c:\MAQ00432.MP4 to whatever you wish z:\psp\MAQ00432.MP4 or whatever, but make sure the name of the output mp4 stays the same, or at least you only change the final three numbers.

Once you have done this, save the bat and double click to run it. It should open up a command window and finally output your changed mp4 to the destination selected. Thats it. run the mp4 to make sure it works, and then finally copy it to your E:\MP_ROOT\100ANV01 folder on your PSP (E: or whatever drive letter the PSP takes).

test it on your PSP and all should work just fine :D should, but probably wont for some stupid reason ;) but post in the doom9 thread:
http://forum.doom9.org/showthread.php?t=100116

if you get stuck, the geniuses on there will help you out :)