On 13/06/2024 13:21, radu.taraib...@gmail.com wrote:
-----Original Message-----
From: ffmpeg-devel<ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of Tobias
Rapp
Sent: joi, 13 iunie 2024 12:52
To:ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [PATCH v3] area changed: scdet filter
On 12/06/2024 21:51,radu.taraib...@gmail.com wrote:
[...]
diff --git a/doc/filters.texi b/doc/filters.texi index
bfa8ccec8b..53814e003b 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -21797,6 +21797,22 @@ Default value is @code{10.}.
@item sc_pass, s
Set the flag to pass scene change frames to the next filter. Default
value is @code{0}
You can enable it if you want to get snapshot of scene change frames
only.
+
+@item mode
+Set the scene change detection method. Default value is @code{-1}
+Available values are:
+
+@table @samp
+@item -1
+Legacy mode for sum of absolute linear differences. Compare frame
with previous only and no delay.
+
+@item 0
+Sum of absolute linear differences. Compare frame with both previous
and next which introduces a 1 frame delay.
+
+@item 1
+Sum of mean of cubic root differences. Compare frame with both
previous and next which introduces a 1 frame delay.
+
+@end table
@end table
@anchor{selectivecolor}
Out of curiosity: How do these three modes roughly compare (CPU)
performance wise?
Mode -1 is virtually equal with mode 0 (no frame clone speedup of mode 0 is
mostly theoretical). Mode 1 is roughly 40% slower, depending on input, it could
benefit from ASM.
I'd prefer if mode "-1" could be used for the default case, and the three modes
get explicit values 0/1/2.
So you want four possible values for mode where the default -1 is the same as
one of the others?
Yes. This pattern is also used for the "shaping" option of the ass
filter, for example.It allows users to make it explicit that the filter
should choose a default (which may vary between versions).
Regarding naming I think that the "Legacy" mode still
has its usecases in the future. Naming it something like "simple" would not
imply that it is deprecated in general, but rather that it has lower precision
(and is possibly faster).
OK, I will rename "Legacy" mode so it doesn't look deprecated to somebody that
can't allow 1 frame delay. Otherwise it shouldn't be used.
Thanks.
Regards, Tobias
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