From e7a0b2e05409489b3bd1decbb51c9ae67f4859c5 Mon Sep 17 00:00:00 2001 From: Stefano Sabatini Date: Tue, 11 Dec 2012 23:31:54 +0100 Subject: doc/filters: itemize select/aselect examples Improve rendering. --- doc/filters.texi | 50 ++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 38 insertions(+), 12 deletions(-) (limited to 'doc') diff --git a/doc/filters.texi b/doc/filters.texi index 1043911f2c..67789001dd 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -4728,45 +4728,71 @@ value means the current frame is more likely to be one (see the example below) The default value of the select expression is "1". -Some examples follow: +@subsection Examples +@itemize +@item +Select all frames in input: @example -# select all frames in input select +@end example -# the above is the same as: +The example above is the same as: +@example select=1 +@end example -# skip all frames: +@item +Skip all frames: +@example select=0 +@end example -# select only I-frames +@item +Select only I-frames: +@example select='eq(pict_type\,I)' +@end example -# select one frame every 100 +@item +Select one frame every 100: +@example select='not(mod(n\,100))' +@end example -# select only frames contained in the 10-20 time interval +@item +Select only frames contained in the 10-20 time interval: +@example select='gte(t\,10)*lte(t\,20)' +@end example -# select only I frames contained in the 10-20 time interval +@item +Select only I frames contained in the 10-20 time interval: +@example select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)' +@end example -# select frames with a minimum distance of 10 seconds +@item +Select frames with a minimum distance of 10 seconds: +@example select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)' +@end example -# use aselect to select only audio frames with samples number > 100 +@item +Use aselect to select only audio frames with samples number > 100: +@example aselect='gt(samples_n\,100)' @end example -Complete example to create a mosaic of the first scenes: - +@item +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. +@end itemize @section asendcmd, sendcmd -- cgit v1.2.3