may want to reduce this value, at the cost of a less effective filter and the
risk of various artefacts.
-If the overlapping value doesn't allow to process the whole input width or
+If the overlapping value doesn't permit processing the whole input width or
height, a warning will be displayed and according borders won't be denoised.
Default value is @var{blocksize}-1, which is the best possible setting.
fade-in effect the output video will have the same intensity as the input video,
at the end of the fade-out transition the output video will be filled with the
selected @option{color}.
-If both duration and nb_frames are specified, duration is used. Default is 0.
+If both duration and nb_frames are specified, duration is used. Default is 0
+(nb_frames is used by default).
@item color, c
Specify the color of the fade. Default is "black".
@end itemize
+@section fftfilt
+Apply arbitrary expressions to samples in frequency domain
+
+@table @option
+@item dc_Y
+Adjust the dc value (gain) of the luma plane of the image. The filter
+accepts an integer value in range @code{0} to @code{1000}. The default
+value is set to @code{0}.
+
+@item dc_U
+Adjust the dc value (gain) of the 1st chroma plane of the image. The
+filter accepts an integer value in range @code{0} to @code{1000}. The
+default value is set to @code{0}.
+
+@item dc_V
+Adjust the dc value (gain) of the 2nd chroma plane of the image. The
+filter accepts an integer value in range @code{0} to @code{1000}. The
+default value is set to @code{0}.
+
+@item weight_Y
+Set the frequency domain weight expression for the luma plane.
+
+@item weight_U
+Set the frequency domain weight expression for the 1st chroma plane.
+
+@item weight_V
+Set the frequency domain weight expression for the 2nd chroma plane.
+
+The filter accepts the following variables:
+@item X
+@item Y
+The coordinates of the current sample.
+
+@item W
+@item H
+The width and height of the image.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+High-pass:
+@example
+fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
+@end example
+
+@item
+Low-pass:
+@example
+fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
+@end example
+
+@item
+Sharpen:
+@example
+fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
+@end example
+
+@end itemize
+
@section field
Extract a single field from an interlaced image using stride