DVD Cropping

[Lighto]

My source appears to have some sort of black border at the left and right side.

Left side: 3px
Right side: 2px

I am only allowed to crop 2 px at a time to MeGUI AVS Creator, I am asking for advice on how to crop the source.

A: Crop 4 px from the left, 2 px from the right
B: Crop 4 px from the left, 4 px from the right

I am leaning towards option B since it keeps the centre of the source where it should be, however 2 px of the picture will be cropped off.

All suggestions and comments will be deeply appreciated. :thanks:

[kalehrl]

I am only allowed to crop 2 px at a time to MeGUI AVS Creator

I believe you can enter number 3 manually but not by pressing arrow buttons.

[Lighto]

I believe you can enter number 3 manually but not by pressing arrow buttons.

I am aware of that but I got this prompt when I do that.
http://i.imgur.com/eOsY9.png

Am I suppose to ignore that and carry on my encoding job?

[kypec]

Am I suppose to ignore that and carry on my encoding job?
You can't ignore that error - it prevents Avisynth script from providing valid video output so there would be nothing to encode for you.
Anyway, why are you so concerned about 1px of over-cropping one side of the frame? Unless your source horizontal resolution is below 20px then I doubt you would ever notice such distortion after encoding...just crop 2px + 4px from the sides and you're good to go.

[Lighto]

You can't ignore that error - it prevents Avisynth script from providing valid video output so there would be nothing to encode for you.
Anyway, why are you so concerned about 1px of over-cropping one side of the frame? Unless your source horizontal resolution is below 20px then I doubt you would ever notice such distortion after encoding...just crop 2px + 4px from the sides and you're good to go.

I am new to ripping and just need some assurance from experienced folks here, I know what to do now.
:thanks:

[Lyle_JP]

The reason you must crop by even numbers on DVD sources is because MPEG-2 uses 4:2:0 chroma sub-sampling. From Wikipedia:
In MPEG-2, Cb and Cr are cosited horizontally. Cb and Cr are sited between pixels in the vertical direction (sited interstitially).

My limited understanding of chroma sub-sampling tells me that the way the color information is paired across two pixels means that cropping on an odd number would render the remaining chroma information useless. Is this essentially correct?

[manono]

I am new to ripping and just need some assurance from experienced folks here, I know what to do now.
:thanks:

You'll lose a heck of a lot more video to your TV set's overscan than you will by cropping a few pixels into the active video.

[Amateur]

just decide what will bother you the least. having 1 pixel of border on that side or cutting into the image by 1 pixel. since it is the border, it's likely that if you overcrop by 1 pixel you won't be missing anything vital.