Video size issue selecting from gallery

[iosdev4rnd]

hi,
i have a video of size 1.6 mb (480 x 270). imported to library too for testing (same video). now when i select this video using picker, the size i get after upload is 2.6 (480 x270). everything is same, except size. why is so ? or i am missing something which needs to be done.

thanks