Originally Posted by ali
I found that all PDF's I tried so far could be cropped manually by editing the MediaBox.
PDF files conforming to older versions of the format can be done that way ... as long as you do not add or delete any characters! -- that will screw up the object offset table, and it's not certain that recovery will work. (If you have some other Box nearby, containing the same data, you may be able to remove it to get the extra character space: if I remember, all Boxes default to MediaBox if they aren't specified.)
Of course, if your editor changes the original newlines behind your back, it will mess up thing even more. PDF files should be treated as binary files.