DVD transfer & aliasing

gallois wrote on 3/10/2004, 11:01 PM

I have some blue screen footage that I transfered from a DVD using one of the free dvd to avi utilities, and the footage looks great except that any contrasty diagonal shows a weird vertical aliasing. Is this an artifact of incorrect sizing or something in the conversion process?

I put a couple screen shots here:

www.hugheshall.com/pics/aliasing1.jpg
www.hugheshall.com/pics/aliasing2.jpg

It's not easy to see, but on diagonals, like the arms or the white shirt, there's a staircase aliasing happening...

The problem is that when I creat a chromakey mask I can't get any clean edges because of this. Has anybody encountered this before??

Comments

farss wrote on 3/10/2004, 11:51 PM

Although I coouldn't say for sure it's probably been shot on DV, which will introduce some degree of artifacting due to its compression method, compressed again to mpeg-2 to go onto DVD and then converted back to DV with a new set of artifacting issues. Amazing it doesn't look worse.
Even straight from the best camera DV will exhibit some staircasing on diagonals, there just isn't that many pixels to start with.
Best solution would be a TINY amount of gaussion blur. But I thought the CC FX let you do that anyway, if not applying the blur first may give you a better key.