vf_fade: add support to options parsing

Extend fade syntax, required by a pending patch.

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index f8a2d1b285..2741f96e4f 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1139,7 +1139,7 @@ For more information about libfreetype, check:
 Apply fade-in/out effect to input video.
 
 It accepts the parameters:
-@var{type}:@var{start_frame}:@var{nb_frames}
+@var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
 
 @var{type} specifies if the effect type, can be either "in" for
 fade-in, or "out" for a fade-out effect.
@@ -1152,6 +1152,22 @@ effect has to last. At the end of the fade-in effect the output video
 will have the same intensity as the input video, at the end of the
 fade-out transition the output video will be completely black.
 
+@var{options} is an optional sequence of @var{key}=@var{value} pairs,
+separated by ":". The description of the accepted options follows.
+
+@table @option
+
+@item type, t
+See @var{type}.
+
+@item start_frame, s
+See @var{start_frame}.
+
+@item nb_frames, n
+See @var{nb_frames}.
+
+@end table
+
 A few usage examples follow, usable too as test scenarios.
 @example
 # fade in first 30 frames of video