Question about file size when transferring

[camilostatis]

Hi, first time on these boards, just wanted to say hi first

Basically I wanted to know why, when transferring a movie from my computer to my ps3 via wifi, the file size that ends up on my ps3 is much bigger than the original file size on my computer. I did some research and the answer I recieved was because it needed to transcoded (not 100% sure what that means) to a format that my "renderer" can play. To my knowledge, my renderer is a ps3 is it not? and the files I have been transferring are mp4, also to my knowledge, playstation 3's can play mp4's so why is it transcoding the file? and how can I make it not so huge?

Also, if I were to just transfer my file via usb stick, I guess the transcoding process would be skipped, in that case, what would be the outcome of the mp4 file?

Thanks for your time.