[FFmpeg-cvslog] documentation: add setdar and setsar description to filters.texi

[Stefano Sabatini]

ffmpeg | branch: master | Stefano Sabatini <stefano.sabatini-lala at poste.it> | Sat Apr  9 13:49:48 2011 +0200| [2fd8756b9f5f5e809bec8f2635216f236106dff4] | committer: Anton Khirnov

documentation: add setdar and setsar description to filters.texi

Signed-off-by: Anton Khirnov <anton at khirnov.net>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2fd8756b9f5f5e809bec8f2635216f236106dff4
---

 doc/filters.texi |   56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 56 insertions(+), 0 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 872afc6..00a954c 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -789,6 +789,36 @@ ratio of the input image.
 
 The default value of @var{width} and @var{height} is 0.
 
+ at anchor{setdar}
+ at section setdar
+
+Set the Display Aspect Ratio for the filter output video.
+
+This is done by changing the specified Sample (aka Pixel) Aspect
+Ratio, according to the following equation:
+ at math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
+
+Keep in mind that this filter does not modify the pixel dimensions of
+the video frame. Also the display aspect ratio set by this filter may
+be changed by later filters in the filterchain, e.g. in case of
+scaling or if another "setdar" or a "setsar" filter is applied.
+
+The filter accepts a parameter string which represents the wanted
+display aspect ratio.
+The parameter can be a floating point number string, or an expression
+of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
+numerator and denominator of the aspect ratio.
+If the parameter is not specified, it is assumed the value "0:1".
+
+For example to change the display aspect ratio to 16:9, specify:
+ at example
+setdar=16:9
+# the above is equivalent to
+setdar=1.77777
+ at end example
+
+See also the "setsar" filter documentation (@pxref{setsar}).
+
 @section setpts
 
 Change the PTS (presentation timestamp) of the input video frames.
@@ -849,6 +879,32 @@ setpts=N/(25*TB)
 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
 @end example
 
+ at anchor{setsar}
+ at section setsar
+
+Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
+
+Note that as a consequence of the application of this filter, the
+output display aspect ratio will change according to the following
+equation:
+ at math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
+
+Keep in mind that the sample aspect ratio set by this filter may be
+changed by later filters in the filterchain, e.g. if another "setsar"
+or a "setdar" filter is applied.
+
+The filter accepts a parameter string which represents the wanted
+sample aspect ratio.
+The parameter can be a floating point number string, or an expression
+of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
+numerator and denominator of the aspect ratio.
+If the parameter is not specified, it is assumed the value "0:1".
+
+For example to change the sample aspect ratio to 10:11, specify:
+ at example
+setsar=10:11
+ at end example
+
 @section settb
 
 Set the timebase to use for the output frames timestamps.