[MPlayer-users] Understand cropping

[T]

Hi,

When I run mplayer crop detection, i.e.,

 mplayer -ao null -vf cropdetect dvd://1

I get:

  [CROP] Crop area: X: 1..709  Y: 83..400  (-vf crop=704:304:4:90).0 

Referring to the man page, which says:

 crop[=w:h:x:y]
       Crops the given part of the image and discards the rest.  Useful
       to remove black bands from widescreen movies.
	  <w>,<h>
	       Cropped width and height, defaults to original width and
	       height.
	  <x>,<y>
	       Position of the cropped picture, defaults to center.

If I gave -vf crop=704:304 to mplayer/mencoder, it will actually use
crop=704:304:8:88 instead of crop=704:304:4:90, correct? Because that's
what I calculate as the actual center, since:

 (720-704)/2 = 8
 (480-304)/2 = 88

If so, why cropdetect suggests crop=704:304:4:90?

thanks

-- 
Tong (remove underscore(s) to reply)
  http://xpt.sourceforge.net/