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doc/filters: itemize crop examples

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Stefano Sabatini 2012-12-15 17:03:12 +01:00
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doc/filters.texi
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@ -1610,42 +1610,72 @@ is approximated to the nearest valid value.
The expression for @var{x} may depend on @var{y}, and the expression
for @var{y} may depend on @var{x}.
Follow some examples:
@subsection Examples
@itemize
@item
Crop the central input area with size 100x100:
@example
# crop the central input area with size 100x100
crop=100:100
# crop the central input area with size 2/3 of the input video
"crop=2/3*in_w:2/3*in_h"
# crop the input video central square
crop=in_h
# delimit the rectangle with the top-left corner placed at position
# 100:100 and the right-bottom corner corresponding to the right-bottom
# corner of the input image.
crop=in_w-100:in_h-100:100:100
# crop 10 pixels from the left and right borders, and 20 pixels from
# the top and bottom borders
"crop=in_w-2*10:in_h-2*20"
# keep only the bottom right quarter of the input image
"crop=in_w/2:in_h/2:in_w/2:in_h/2"
# crop height for getting Greek harmony
"crop=in_w:1/PHI*in_w"
# trembling effect
"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"
# erratic camera effect depending on timestamp
"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
# set x depending on the value of y
"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
@end example
@item
Crop the central input area with size 2/3 of the input video:
@example
crop=2/3*in_w:2/3*in_h
@end example
@item
Crop the input video central square:
@example
crop=in_h
@end example
@item
Delimit the rectangle with the top-left corner placed at position
100:100 and the right-bottom corner corresponding to the right-bottom
corner of the input image:
@example
crop=in_w-100:in_h-100:100:100
@end example
@item
Crop 10 pixels from the left and right borders, and 20 pixels from
the top and bottom borders
@example
crop=in_w-2*10:in_h-2*20
@end example
@item
Keep only the bottom right quarter of the input image:
@example
crop=in_w/2:in_h/2:in_w/2:in_h/2
@end example
@item
Crop height for getting Greek harmony:
@example
crop=in_w:1/PHI*in_w
@end example
@item
Appply trembling effect:
@example
crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)
@end example
@item
Apply erratic camera effect depending on timestamp:
@example
crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
@end example
@item
Set x depending on the value of y:
@example
crop=in_w/2:in_h/2:y:10+10*sin(n/10)
@end example
@end itemize
@section cropdetect
Auto-detect crop size.