how do i decrease the size of a file?

Question

it has the formats of BUP, VOB, and IFO.

NOT USING FILE COMPRESSION!

Answer 1

vob, bup, and ifo is video data from a DVD. You can re-encode the video at a lower resolution to make it smaller. This takes some time, and loses picture quality, though.

(For example, I often record video DVDs at half-resolution. It makes the picture quality about as good as a VHS VCR -- noticeably worse than DVD -- but it lets me fit 4 hours of video onto a 2-hour DVD blank.)