Cropping in AutoGK

[VistaXP]

Okay, I like to remove of course the top and bottom black bars on a widescreen, also in some movies there's a small bit of black on the left side of a movie about 2-4 pixel, so I like to remove that as well. I know AutoGK have auto crop but its not removing the black bars completely so I like to do it manually. How would I accurately calculate the ammount of cropping?


Note: I use Virtualdub Mod, as its easier for cropping. Could I use those x's y's for autgk?

[mats.hogberg]

Stick to what AutoGK suggests - you can't crop "pixel perfect", as the frame size has to be multiples of 8

/Mats

[VistaXP]

what happens if its not multiple of 8?

[mats.hogberg]

The AVI wont play at all, or be a complete mess if it does.. It's not a shotcoming of AutoGK - that's the way XviD and DivX codecs work.

/Mats

[celtic_druid]

Actually XviD can handle mod4 for horizontal and mod2 for vertical. No idea about DivX.You should stick with mod16 though which would mean cropping 8 pixels from each side so 704x???. That's only if you aren't resizing though.

If you want to do things manually, you are really using the wrong app.

[VistaXP]

can you please provide a guide or something so i can better understand the mod 8 and mod16 thing. Of have an idea but like to learn a bit more.

[mats.hogberg]

mod8 means multiple of 8, mod16 multiple of 16.
I've made a rule of always resizing to a multiple of 8, which has never failed me so far.

/Mats

[VistaXP]

nm thank you.

[manono]

If progressive and YV12, the cropping can be Mod2 for both the height and width:

http://www.avisynth.org/Crop

It's the resize that should be Mod16, something AutoGK follows. If the autocrop isn't doing the job, then you can go into the hidden options and tighten up the autocrop, or crop manually:

- Sometimes auto crop used with default parameters by AutoGK cannot totally remove black bars or removes too much of a movie material. In this case "Tune auto crop parameters" is very handy. Threshold defines how sensitive auto crop will be: the higher the value the more cropping will be done. To completely disable audio crop you can set threshold to 0. "Number of frames to examine" is useful parameter to change if movie is a mixture of full screen/wide screen shots, so by selecting different frames that auto crop examines you can improve cropping process. "Starting frame" can help auto crop in situation when you have a full screen logo as a part of widescreen movie, in which case autocrop might decide that the whole source is full screen. By selecting a different starting frames you force auto crop not to examine irrelevant starting movie sequence. "Force cropping" option allows you to crop additional pixels after autocrop operation (if you find that you need to always crop several more pixels you can use this option). If you disable autocrop with threshold 0 then "force cropping" option becomes fully manual crop. Remember always to check how movie looks like after you set new auto crop parameters using Preview function of AutoGK.

http://www.autogk.me.uk/modules.php?name=TutorialEN#6