avfilter: add xmedian filter

Changelog

@@ -28,6 +28,7 @@ version <next>:
 - asoftclip filter
 - Support decoding of HEVC 4:4:4 content in vdpau
 - colorhold filter
+- xmedian filter
 
 
 version 4.1:

doc/filters.texi

@@ -18418,6 +18418,20 @@ Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for
 Default is @code{3}.
 @end table
 
+@section xmedian
+Pick median pixels from several input videos.
+
+The filter accept the following options:
+
+@table @option
+@item nb_inputs
+Set number of inputs. This must be odd number.
+Default is 3. Allowed range is from 3 to 255.
+
+@item planes
+Set which planes to filter. Default value is @code{15}, by which all planes are processed.
+@end table
+
 @section xstack
 Stack video inputs into custom layout.
 

libavfilter/Makefile

@@ -421,6 +421,7 @@ OBJS-$(CONFIG_W3FDIF_FILTER)                 += vf_w3fdif.o
 OBJS-$(CONFIG_WAVEFORM_FILTER)               += vf_waveform.o
 OBJS-$(CONFIG_WEAVE_FILTER)                  += vf_weave.o
 OBJS-$(CONFIG_XBR_FILTER)                    += vf_xbr.o
+OBJS-$(CONFIG_XMEDIAN_FILTER)                += vf_xmedian.o framesync.o
 OBJS-$(CONFIG_XSTACK_FILTER)                 += vf_stack.o framesync.o
 OBJS-$(CONFIG_YADIF_FILTER)                  += vf_yadif.o yadif_common.o
 OBJS-$(CONFIG_YADIF_CUDA_FILTER)             += vf_yadif_cuda.o vf_yadif_cuda.ptx.o \

libavfilter/allfilters.c

@@ -400,6 +400,7 @@ extern AVFilter ff_vf_w3fdif;
 extern AVFilter ff_vf_waveform;
 extern AVFilter ff_vf_weave;
 extern AVFilter ff_vf_xbr;
+extern AVFilter ff_vf_xmedian;
 extern AVFilter ff_vf_xstack;
 extern AVFilter ff_vf_yadif;
 extern AVFilter ff_vf_yadif_cuda;

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   7
-#define LIBAVFILTER_VERSION_MINOR  51
+#define LIBAVFILTER_VERSION_MINOR  52
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \