[FFmpeg-cvslog] vf_pad: add an example employing the sar variable

[Stefano Sabatini]

ffmpeg | branch: master | Stefano Sabatini <stefano.sabatini-lala at poste.it> | Sat Jul 30 18:23:24 2011 +0200| [3b5ddf07c0c4ab6a0d347d92ff8d9cfbac6b66ed] | committer: Stefano Sabatini

vf_pad: add an example employing the sar variable

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3b5ddf07c0c4ab6a0d347d92ff8d9cfbac6b66ed
---

 doc/filters.texi |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 68a82b7..2747402 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1264,6 +1264,12 @@ pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
 # pad the input to get a final w/h ratio of 16:9
 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
 
+# 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
+pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
+
 # double output size and put the input video in the bottom-right
 # corner of the output padded area
 pad="2*iw:2*ih:ow-iw:oh-ih"