avfilter/vf_vectorscope: make background opacity customizable

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index f141daecef..6f378d7153 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -12581,6 +12581,9 @@ Draw graticule for white point.
 @item black
 Draw graticule for black point.
 @end table
+
+@item bgopacity, b
+Set background opacity.
 @end table
 
 @anchor{vidstabdetect}