What about your
EYES?
I do only make comparisons using my eyes on a PC Monitor or my Panasonic 32" 16:9 TV Set. In a clear served RGB input out of the to RGB output settet SAP There you can even see if a GOP is set to 15 or 30 (the picture is that clear and detailed that you can recognise the "pumping" at the change to the next "I" Frame. Even on orig DVDs!
Thats why GOPs longer than 15 is no longer an issue for me and my taste.
Today you got a normal TV and you see your backups in a quality your TV can offer. But some Day, you do purchase a good LCD or a good CRT like mine mentioned above and THEN you can see using your good eyes what your encodings are made of.
So ..... I do compare outputs NOT on mathematical values, but at least on the best comparison technique given: The PC Monitor.
Do import the encoded and the orig stream in an avisynth script like this:
Code:
encoded1 = mpeg2source("encoded1.d2v").subtitle("encoded1",10,10)
encoded2 = mpeg2source("encoded2.d2v").subtitle("encoded2",10,10)
Interleave(encoded1, encoded2)
Now open that in Vdub und move frame per frame forward.
you then can switch to the orig and the encoded one by back and forth.
THATs a comparison you can trust in as your EYES will be the ones which do enjoy the movie finally.