Keeping the Image Quality the same when encoding at lower bitrates to MP4.

[Balefor]

Hello. I've recently discovered the wonderful compression of MPEG-4 for the PSP. I know MPEG-4 has been around for quite a while I just never had a reason to encode in it till now. I would like to know how I can keep the image quality the same as its original quality video. For example: The original video looks nice and clean with no pixelation. Is there a way to get the same great look of the original video at lower bitrates? Or does anyone have any suggesstions as to what codec I should use to fit the most amount of video on a memory stick (1GB), but still have the video be watchable? And as to what encoder and settings? I've been using the Datel PSP Media Manager for conversion. I would use SUPER but SUPER is just too slow. So what should I do? Awaiting replies if any is to be had.

[Balefor]

Never Mind I think I know my answer. I think I'll just have to stick with AVC not that thats not a bad choice but if anyone has any better ideas ono to what i should use to get what im looking for I'm game.