[FFmpeg-cvslog] lavfi/overlay_vaapi: set defalut alpha value as 1.0

[Fei Wang]

ffmpeg | branch: master | Fei Wang <fei.w.wang-at-intel.com at ffmpeg.org> | Fri Aug  5 14:11:19 2022 +0800| [26890b6b6770214ad63fc9c9564ac75b3227f708] | committer: Haihao Xiang

lavfi/overlay_vaapi: set defalut alpha value as 1.0

The present default value of 0 will render the overlay video invisible.
A default of 1.0 is consistent with most common use cases.

Signed-off-by: Fei Wang <fei.w.wang at intel.com>
Reviewed-by: Philip Langdale <philipl at overt.org>
Signed-off-by: Haihao Xiang <haihao.xiang at intel.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=26890b6b6770214ad63fc9c9564ac75b3227f708
---

 doc/filters.texi               | 2 +-
 libavfilter/vf_overlay_vaapi.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index af7d60ca44..c85c33a104 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -26183,7 +26183,7 @@ Default value is the height of input overlay video.
 @item alpha
 Set transparency of overlaid video. Allowed range is 0.0 to 1.0.
 Higher value means lower transparency.
-Default value is @code{0.0}.
+Default value is @code{1.0}.
 
 @end table
 
diff --git a/libavfilter/vf_overlay_vaapi.c b/libavfilter/vf_overlay_vaapi.c
index b3a624ae15..3e6a0de13f 100644
--- a/libavfilter/vf_overlay_vaapi.c
+++ b/libavfilter/vf_overlay_vaapi.c
@@ -380,7 +380,7 @@ static const AVOption overlay_vaapi_options[] = {
     { "h", "Overlay height",
       OFFSET(overlay_oh), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, .flags = FLAGS },
     { "alpha", "Overlay global alpha",
-      OFFSET(alpha), AV_OPT_TYPE_FLOAT, { .dbl = 0.0}, 0.0, 1.0, .flags = FLAGS},
+      OFFSET(alpha), AV_OPT_TYPE_FLOAT, { .dbl = 1.0}, 0.0, 1.0, .flags = FLAGS},
     { NULL },
 };