avfilter/vf_pad: Add eval=frame support

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

1 files changed, 18 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 6ad2db2728..45a7569a80 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -10422,6 +10422,24 @@ Specify the color of the padded area. For the syntax of this option,
 check the "Color" section in the ffmpeg-utils manual.
 
 The default value of @var{color} is "black".
+
+@item eval
+Specify when to evaluate  @var{width}, @var{height}, @var{x} and @var{y} expression.
+
+It accepts the following values:
+
+@table @samp
+@item init
+Only evaluate expressions once during the filter initialization or when
+a command is processed.
+
+@item frame
+Evaluate expressions for each incoming frame.
+
+@end table
+
+Default value is @samp{init}.
+
 @end table
 
 The value for the @var{width}, @var{height}, @var{x}, and @var{y}