AutoGK: film size

[MrMagooba]

I noticed after backing up Spiderman, that the screen size looked to be smaller, so I ran the dvd and it was, I decided to test with another film, this time Black Hawk Down, and again it looked to have cropped some of the film away - width wise, height is fine.
When I used DVD2SVCD I used a program called AutoFitCD (as you may notice, I use user friendly progs!) and it converted the film to the proper size.

Why is AutoGK croping the width of my films and is there any way of making it convert the film at it's proper resolution/aspect ratio.

(I'm new to AVI encoding, which is why I'm using AutoGK! I tried GK first and was a little confused!!)

Thanks.

[manono]

Hi-

SVCDs are different from avi's. They get resized on playback (how much depends on if it's encoded with a 16:9 or 4:3 DAR), as do the original DVDs, and ordinarily aren't cropped on the width. So if you're encoding an anamorphic 16:9 DVD into a 4:3 SVCD (as per your 2 examples), about all you have to do is to add the bars above and below. And if there was some small amount of black on the left and right sides on the DVD, it'll stay, and will be hidden by your TV's overscan. If you were to encode an .avi into SVCD, then you might see some cropping into the sides of the .avi to maintain the AR (depending on the original .avi resolution).

Avi's are different since they are ordinarily encoded already resized. You first crop away all the black bars on all 4 sides, but you may have to crop some more away from the video to maintain proper AR. It can be disputed whether or not it's a good idea to crop into the video to keep the AR, or whether it's better to leave some of the black showing. Personally, I don't want any of the black at all remaining.

Then the question becomes whether to do the remaining cropping from the top and bottom, or from the sides. If you crop from the top and bottom, then you run the risk of a 2.35:1 movie (640x272) turning into a 2.50:1 movie (640x256). And that makes it even more narrow than before. So, again, I come down on the side that prefers to do the remaining cropping from the left and right sides. If AutoCrop is doing its job correctly, then there should be only a few pixels cropped from each side. You're right, in that there may be some picture missing from the sides. You're wrong in concluding that it therefore has improper AR.

Maybe Doom9's article on Aspect Ratios (http://www.doom9.org/aspectratios.htm) will help to explain it better.

[ukb007]

The reason why black bars should be completely cropped away is that a lot of bits are wasted in the margin between the picture and the black bar. These bits can be usefully put into the movie itself by doing away with those black bars.

The few pixels of cut into the picture then is necessary because of the AR restrictions of the codec. It may be possible to develop a codec without these restrictions. Or the movie directors may employ an AR keeping in mind the future DivX/XviD application...:)

Players also have AR restrictions. They meet these by adding black on the sides or above and below as required.

Regards.