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diff --git a/doc/filters.texi b/doc/filters.texi index c71fd48..f3f7718 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -183,6 +183,66 @@ threshold, and defaults to 98. @var{threshold} is the threshold below which a pixel value is considered black, and defaults to 32. +@section boxblur + +Apply boxblur algorithm to the input video. + +This filter accepts the parameters: +@var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power} + +Chroma and alpha parameters are optional, if not specified they default +to the corresponding values set for @var{luma_radius} and +@var{luma_power}. + +@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent +the radius in pixels of the box used for blurring the corresponding +input plane. They are expressions, and can contain the following +constants: +@table @option +@item w, h +the input width and heigth in pixels + +@item cw, ch +the input chroma image width and height in pixels + +@item hsub, vsub +horizontal and vertical chroma subsample values. For example for the +pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. +@end table + +The radius must be a non-negative number, and must not be greater than +the value of the expression @code{min(w,h)/2} for the luma and alpha planes, +and of @code{min(cw,ch)/2} for the chroma planes. + +@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent +how many times the boxblur filter is applied to the corresponding +plane. + +Some examples follow: + +@itemize + +@item +Apply a boxblur filter with luma, chroma, and alpha radius +set to 2: +@example +boxblur=2:1 +@end example + +@item +Set luma radius to 2, alpha and chroma radius to 0 +@example +boxblur=2:1:0:0:0:0 +@end example + +@item +Set luma and chroma radius to a fraction of the video dimension +@example +boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1 +@end example + +@end itemize + @section copy Copy the input source unchanged to the output. Mainly useful for |