Picture break-up when editing Mpeg files

Sometimes if I have a DVDSP project, and I am trying to do a few internal edits on a single clip...setting the duration shorter and butting up a new clip at the end of the video on the same track...most of the time, there is a glitch where there's about a dozen black "bricks" on the picture for the first frame on the new clip. Sometimes there isn't. I'm wondering what's making the difference. Usually if I'm going to do any internal edits, I'll do it when the video fades to black. Sometimes, I have to cut just a little piece out, and usually I get this glitch, but occasionally not.

Just trying to figure out why this happens...and what can be done to not get the glitch if possible.

Thanks!

Casey Petersen
www.unitedvideoinc.com

""and I am trying to do a few internal edits on a single clip""

How? What applications are you using to EDIT MPEG-2? To my knowledge, MPEG-2 is NOT EDITABLE?

MPEG-2 is Long GOP (groups of pictures) and can not be cut apart willy nilly. Only the first frame is a full frame. Each frame after the full frame only has the changed pixels from th last frame, etc.

This is all within DVDSP...adjusting the Clip Start Trim and the Duration.

I'm just wondering why this works sometimes, but usually not...just lucky?


Thanks!
Casey

Again, every 15th frame is a full frame. all the rest of the 14 are not a full frame rather differences between first full frame..1 and next-next-next......13.14.15. You can't just arbitratorally remove and shorten a GOP structure.

The only reason Final Cut Pro is able to edit HDV (MPEG-2) because of a codec that rebuilds a full frame where ever the FCP Playhead stop. pretty slick, but DVD Studio is not an editor, just assembler or assets already cooked.

Hmm...that's kind of what I thought.

I guess those few times were just luck.

The reason why I can do it consistently on a black frame is that you simply can't see the break-up.

Thanks!
Casey