Apply boxblur algorithm to the input video.
This filter accepts the parameters: luma_radius:luma_power:chroma_radius:chroma_power:alpha_radius:alpha_power
Chroma and alpha parameters are optional, if not specified they default to the corresponding values set for luma_radius and luma_power.
luma_radius, chroma_radius, and 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:
- w, h
-
the input width and height in pixels
- cw, ch
-
the input chroma image width and height in pixels
- hsub, vsub
-
horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" hsub is 2 and vsub is 1.
The radius must be a non-negative number, and must not be greater than
the value of the expression min(w,h)/2 for the luma and alpha planes,
and of min(cw,ch)/2 for the chroma planes.
luma_power, chroma_power, and alpha_power represent how many times the boxblur filter is applied to the corresponding plane.
Some examples follow:
-
Apply a boxblur filter with luma, chroma, and alpha radius set to 2:
boxblur=2:1
-
Set luma radius to 2, alpha and chroma radius to 0
boxblur=2:1:0:0:0:0
-
Set luma and chroma radius to a fraction of the video dimension
boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1