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PSP uses mpeg4 as a video format. However, there are different types of codecs of audio that a video format can have. Also a video can have a certain quality and compression. Lets say you want to be able do take a video file and put it onto a PSP's memory stick.

If the file format is not an mp4 you will have to convert it. To do this, you can use programs on the web called video converters. Either search for a "PSP video converter" on the web or check out PSP Video 9. PSP Video 9 is a free PSP video converter. They make their money on donations and ads. If you like it fill free to donate.

There are other conversion programs out there that convert many different video file formats and one of my favorites is Magic Video Converter. It is not free but very easy to use.

Converting a video file to PSP mp4 video with PSP Video 9

Once the program is downloaded and installed the program open it up. You will usually see a browse button or an open button to find the file that is to be converted. Browse for that file and open it up. Below is an image of PSP Video 9 converting a video. Converting a video is also called transcoding.

Once the video is converted, there will be the old file and the newly converted file and their directories listed on either side. The video can be directly converted to the PSP or to another part of the computer's hard drive.

If you had chosen not to convert the video file directly to the PSP itself, find the newly transcoded PSP video and put it in the Video directory on the PSP. To do this go to My Computer in XP or Computer is Vista and you should find a removable disk. This happens after the PSP has been connected and identified by Windows.