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View Full Version : A split screen tool exist to A/B compare encodes?


kikker
24th April 2009, 03:09
There are numerous technical and mathematical tools with which to measure the quality of an encode. However, the subjective test is the best one there. I'm trying to determine the maximum -crf value that would give visual transparency to the source for the equipment I would be using and at the distance I would be viewing it.

So, I thought that if I can carry out a series of encodes at various -crf levels and perhaps change up an x264 parameter or two just for kicks to "see" what they do to the picture, this task could probably be best performed with the aid of a split screen A/B compare.

Does something like this exist, or only in the professional domain?

Keiyakusha
24th April 2009, 03:18
Avisynth: StackVertical(), StackHorizontal(), Interleave()

poisondeathray
24th April 2009, 03:20
You can also use avisynth and AvsP, to switch between the scripts of each video quickly with the number keys (e.g. like you would tabs in a browser). It makes comparing specific frames very fast (e.g. you might be comparing the detail of a specific frame between encodes)

cacepi
24th April 2009, 03:22
Does something like this exist, or only in the professional domain?
You could try ShowFiveVersions() (http://avisynth.org/mediawiki/ShowFiveVersions").

kikker
24th April 2009, 03:59
Thanks for the tips. I also found a script in the 'Share function' section AVIsynth page called SeeTheDifference. http://avisynth.org/mediawiki/SeeTheDifference

I'll give one of these methods a go tomorrow.

Comatose
24th April 2009, 08:41
Are you looking for split screen, as in half the screen from one clip, and the other from another clip?

Try something like this:
a=Blackness(color=$FFFF00) # or another source
a=a.crop((a.width/2)+2,0,0,0).AddBorders(0,0,2,0)
b=Blackness(color=$FF00FF) # or another source
b=b.crop(0,0,-(b.width/2)-2,0).AddBorders(2,0,0,0)
stackhorizontal(a,b)

But personally, I find interleave(a,b) (without modifying them) to be better, because you can compare the same area of a frame very easily.