Using MeGUI to encode videos for PSP?

Hi, ever since I've had a PSP (PSP-3000 model), I've never been able to watch a video on it. It says that the file has to be a MP4, but even if the file is MP4, my PSP tells me that the format is unsupported. I tried using MeGUI with the x264:PSP setting, but it didn't work either. Can anyone with a PSP who doesn't have this problem tell me what I can do to make my MP4 videos work? Also, I did see the XviD4PSP thread, but that program doesn't have MP4 as one of its import formats.

Main profile Level 3.0 3 or less ref frames No b-pyramid Weightp 1

this is what you need... Code:

Thanks guys. I used the line that b66pak posted and Lighto was right about the resolution. It worked, but the audio didn't work though. It was making an horrible sound. All I did with the audio was extract the mp3 from the original file and mux it with the new encoded video. Are there restrictions when it comes to audio as well?