lavfi: add smartblur filter

This is a port of the MPlayer smartblur filter (libmpcodecs/vf_smartblur.c)
by Michael Niedermayer.
Signed-off-by: Stefano Sabatini <stefasab@gmail.com>

Changelog

@@ -54,6 +54,7 @@ version next:
 - Ut Video encoder
 - Matroska demuxer now identifies SRT subtitles as AV_CODEC_ID_SUBRIP
   instead of AV_CODEC_ID_TEXT
+- smartblur filter ported from MPlayer
 
 
 version 0.11:

configure

@@ -1867,6 +1867,7 @@ ocv_filter_deps="libopencv"
 pan_filter_deps="swresample"
 removelogo_filter_deps="avcodec avformat swscale"
 scale_filter_deps="swscale"
+smartblur_filter_deps="gpl swscale"
 select_filter_deps="avcodec"
 showspectrum_filter_deps="avcodec"
 super2xsai_filter_deps="gpl"

doc/filters.texi

@@ -3253,6 +3253,35 @@ not specified it will use the default value of 16.
 Adding this in the beginning of filter chains should make filtering
 faster due to better use of the memory cache.
 
+@section smartblur
+
+Blur the input video without impacting the outlines.
+
+The filter accepts the following parameters:
+@var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
+
+Parameters prefixed by @var{luma} indicate that they work on the
+luminance of the pixels whereas parameters prefixed by @var{chroma}
+refer to the chrominance of the pixels.
+
+If the chroma parameters are not set, the luma parameters are used for
+either the luminance and the chrominance of the pixels.
+
+@var{luma_radius} or @var{chroma_radius} must be a float number in the
+range [0.1,5.0] that specifies the variance of the gaussian filter
+used to blur the image (slower if larger).
+
+@var{luma_strength} or @var{chroma_strength} must be a float number in
+the range [-1.0,1.0] that configures the blurring. A value included in
+[0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
+will sharpen the image.
+
+@var{luma_threshold} or @var{chroma_threshold} must be an integer in
+the range [-30,30] that is used as a coefficient to determine whether
+a pixel should be blurred or not. A value of 0 will filter all the
+image, a value included in [0,30] will filter flat areas and a value
+included in [-30,0] will filter edges.
+
 @section split
 
 Split input video into several identical outputs.

libavfilter/Makefile

@@ -14,6 +14,7 @@ FFLIBS-$(CONFIG_MOVIE_FILTER)                += avformat avcodec
 FFLIBS-$(CONFIG_PAN_FILTER)                  += swresample
 FFLIBS-$(CONFIG_REMOVELOGO_FILTER)           += avformat avcodec
 FFLIBS-$(CONFIG_MP_FILTER)                   += avcodec postproc
+FFLIBS-$(CONFIG_SMARTBLUR_FILTER)            += swscale
 
 HEADERS = asrc_abuffer.h                                                \
           avcodec.h                                                     \
@@ -125,6 +126,7 @@ OBJS-$(CONFIG_SETSAR_FILTER)                 += vf_aspect.o
 OBJS-$(CONFIG_SETTB_FILTER)                  += f_settb.o
 OBJS-$(CONFIG_SHOWINFO_FILTER)               += vf_showinfo.o
 OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o
+OBJS-$(CONFIG_SMARTBLUR_FILTER)              += vf_smartblur.o
 OBJS-$(CONFIG_SPLIT_FILTER)                  += split.o
 OBJS-$(CONFIG_SUPER2XSAI_FILTER)             += vf_super2xsai.o
 OBJS-$(CONFIG_SWAPUV_FILTER)                 += vf_swapuv.o

libavfilter/allfilters.c

@@ -116,6 +116,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (SETTB,       settb,       vf);
     REGISTER_FILTER (SHOWINFO,    showinfo,    vf);
     REGISTER_FILTER (SLICIFY,     slicify,     vf);
+    REGISTER_FILTER (SMARTBLUR,   smartblur,   vf);
     REGISTER_FILTER (SPLIT,       split,       vf);
     REGISTER_FILTER (SUPER2XSAI,  super2xsai,  vf);
     REGISTER_FILTER (SWAPUV,      swapuv,      vf);

libavfilter/version.h

@@ -29,8 +29,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  13
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR  14
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \