I am writing some software that analyses some underwater footage of the Great Barrier Reef, we are towing a camera at roughly 2 mph and capturing on DVC-Pro. I am converting the footage to MPEG. When we are analysing the footage and something of interst goes past the user will pause the image and take a snapshot of that frame, be it a fish, crab, prawn, reef, shark etc. The problem is that we store (in a database) a reference to that frame in either milliseconds or a frame number but when we attempt to return to that exact frame it is close but never exact. Now I understand a little about the compression and that it will return to the I frame frame which generally occurs about every 12ish frames. My question is; is there any way using mpegs I can return to that exact frame, is there an I frame only MPEG, is this a special CODEC. Any help would be appreciated. I do not want to use AVI files that I know we can return to the exact frame.