On 11/10/17, Nicolas George <geo...@nsup.org> wrote: > Le septidi 17 brumaire, an CCXXVI, Paul B Mahol a ecrit : >> Signed-off-by: Paul B Mahol <one...@gmail.com> >> --- >> doc/filters.texi | 5 +++++ >> libavfilter/vf_tile.c | 53 >> ++++++++++++++++++++++++++++++++++++++++++--------- >> 2 files changed, 49 insertions(+), 9 deletions(-) >> >> diff --git a/doc/filters.texi b/doc/filters.texi >> index 2ba6e04166..a6d537485b 100644 >> --- a/doc/filters.texi >> +++ b/doc/filters.texi >> @@ -14439,6 +14439,11 @@ refer to the pad video filter. >> Specify the color of the unused area. For the syntax of this option, >> check the >> "Color" section in the ffmpeg-utils manual. The default value of >> @var{color} >> is "black". >> + > >> +@item skip >> +Set the number of frames to skip from input before rendering output >> frame. >> +The default value is @code{0}, meaning skip @var{nb_frames} frames. If it >> is more >> +than @var{nb_frames} its is set to @var{nb_frames}. > > I had trouble understanding the logic of the code, until I realized the > problem was here: I think the documentation does not explain well what > the option is meant to do. > > If I understand correctly, using an example: if a 5x4 tile, the normal > mapping is: > > out 0 <- in 0 .. in 19 > out 1 <- in 20 .. in 39 > out 2 <- in 40 .. in 59 > out 3 <- in 60 .. in 79 > > But if "skip" is set to 15, it becomes: > > out 0 <- in 0 .. in 19 > out 1 <- in 15 .. in 34 > out 2 <- in 30 .. in 49 > out 3 <- in 45 .. in 64 > > In other words, the output frames overlap by nb_frames - skip input > frames. > > Is it what you intended?
Yes. > > If so, then the doc needs to be clarified. And I think the name of the > option is misleading. What about "step"? Or maybe "period"? It could be... > > Or possibly even better: reverse the direction of the option "overlap=5" > instead of "step=15". What if user sets overlap to same or greater than nb_frames, just error out? _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel