vf_fps: add 'start_time' option

This allows for dropping or duplication to match a particular start time.

1 files changed, 8 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 2ee5ad556e..52971c76e9 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1241,6 +1241,14 @@ This filter accepts the following named parameters:
 @item fps
 Desired output framerate.
 
+@item start_time
+Assume the first PTS should be the given value, in seconds. This allows for
+padding/trimming at the start of stream. By default, no assumption is made
+about the first frame's expected PTS, so no padding or trimming is done.
+For example, this could be set to 0 to pad the beginning with duplicates of
+the first frame if a video stream starts after the audio stream or to trim any
+frames with a negative PTS.
+
 @end table
 
 @anchor{frei0r}