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doc/filters: itemize examples for pad filter, and fix a few typos

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Stefano Sabatini 2012-08-21 12:34:10 +02:00
parent bc151aee60
commit 4a32b30e0c
1 changed files with 39 additions and 16 deletions
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doc/filters.texi
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@ -2795,36 +2795,59 @@ The default value of @var{color} is "black".
@end table
Some examples follow:
@section Examples
@itemize
@item
Add paddings with color "violet" to the input video. Output video
size is 640x480, the top-left corner of the input video is placed at
column 0, row 40:
@example
# Add paddings with color "violet" to the input video. Output video
# size is 640x480, the top-left corner of the input video is placed at
# column 0, row 40.
pad=640:480:0:40:violet
@end example
# pad the input to get an output with dimensions increased bt 3/2,
# and put the input video at the center of the padded area
@item
Pad the input to get an output with dimensions increased by 3/2,
and put the input video at the center of the padded area:
@example
pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
@end example
# pad the input to get a squared output with size equal to the maximum
# value between the input width and height, and put the input video at
# the center of the padded area
@item
Pad the input to get a squared output with size equal to the maximum
value between the input width and height, and put the input video at
the center of the padded area:
@example
pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
@end example
# pad the input to get a final w/h ratio of 16:9
@item
Pad the input to get a final w/h ratio of 16:9:
@example
pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
@end example
# for anamorphic video, in order to set the output display aspect ratio,
# it is necessary to use sar in the expression, according to the relation:
# (ih * X / ih) * sar = output_dar
# X = output_dar / sar
@item
In case of anamorphic video, in order to set the output display aspect
correctly, it is necessary to use @var{sar} in the expression,
according to the relation:
@example
(ih * X / ih) * sar = output_dar
X = output_dar / sar
@end example
Thus the previous example needs to be modified to:
@example
pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
@end example
# double output size and put the input video in the bottom-right
# corner of the output padded area
@item
Double output size and put the input video in the bottom-right
corner of the output padded area:
@example
pad="2*iw:2*ih:ow-iw:oh-ih"
@end example
@end itemize
@section pixdesctest