lavfi/select: add scene detection.

Based on the shotdetect algorithm (http://shotdetect.nonutc.fr/ by Johan
MATHE johan.mathe tremplin-utc.net).

1 files changed, 15 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 324a1542e8..d9d503f610 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2603,6 +2603,12 @@ the frame is bottom-field-first
 @item pos
 the position in the file of the filtered frame, -1 if the information
 is not available (e.g. for synthetic video)
+
+@item scene
+value between 0 and 1 to indicate a new scene; a low value reflects a low
+probability for the current frame to introduce a new scene, while a higher
+value means the current frame is more likely to be one (see the example below)
+
 @end table
 
 The default value of the select expression is "1".
@@ -2635,6 +2641,15 @@ select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
 @end example
 
+Complete example to create a mosaic of the first scenes:
+
+@example
+ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
+@end example
+
+Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
+choice.
+
 @section setdar, setsar
 
 The @code{setdar} filter sets the Display Aspect Ratio for the filter