boxblur_opencl

Apply a boxblur algorithm to the input video.

It accepts the following parameters:

'luma_radius, lr'

'luma_power, lp'

'chroma_radius, cr'

'chroma_power, cp'

'alpha_radius, ar'

'alpha_power, ap'

A description of the accepted options follows.

'luma_radius, lr'

'chroma_radius, cr'

'alpha_radius, ar'

Set an expression for the box radius in pixels used for blurring the corresponding input plane.

The radius value 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.

Default value for 'luma_radius' is "2". If not specified, 'chroma_radius' and 'alpha_radius' default to the corresponding value set for 'luma_radius'.

The expressions 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'

The horizontal and vertical chroma subsample values. For example, for the pixel format "yuv422p", hsub is 2 and vsub is 1.

'luma_power, lp'

'chroma_power, cp'

'alpha_power, ap'

Specify how many times the boxblur filter is applied to the corresponding plane.

Default value for 'luma_power' is 2. If not specified, 'chroma_power' and 'alpha_power' default to the corresponding value set for 'luma_power'.

A value of 0 will disable the effect.

Command line examples

Apply boxblur filter, setting each pixel of the output to the average value of box-radiuses luma_radius, chroma_radius, alpha_radius for each plane respectively. The filter will apply luma_power, chroma_power, alpha_power times onto the corresponding plane. For pixels on the edges of the image, the radius does not extend beyond the image boundaries, and so out-of-range coordinates are not used in the calculations.

• Apply a boxblur filter with the luma, chroma, and alpha radius set to 2 and luma, chroma, and alpha power set to 3. The filter will run 3 times with box-radius set to 2 for every plane of the image.

  -i INPUT -vf "hwupload, boxblur_opencl=luma_radius=2:luma_power=3, hwdownload" OUTPUT
  -i INPUT -vf "hwupload, boxblur_opencl=2:3, hwdownload" OUTPUT
  

• Apply a boxblur filter with luma radius set to 2, luma_power to 1, chroma_radius to 4, chroma_power to 5, alpha_radius to 3 and alpha_power to 7.

  For the luma plane, a 2x2 box radius will be run once.

  For the chroma plane, a 4x4 box radius will be run 5 times.

  For the alpha plane, a 3x3 box radius will be run 7 times.

  -i INPUT -vf "hwupload, boxblur_opencl=2:1:4:5:3:7, hwdownload" OUTPUT