avfilter: add maskedmerge filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Changelog

@@ -12,6 +12,7 @@ version <next>:
 - tremolo filter
 - agate filter
 - chromakey filter
+- maskedmerge filter
 
 
 version 2.8:

doc/filters.texi

@@ -7625,6 +7625,25 @@ lutyuv=y='bitand(val, 128+64+32)'
 @end example
 @end itemize
 
+@section maskedmerge
+
+Merge the first input stream with the second input stream using per pixel
+weights in the third input stream.
+
+A value of 0 in the third stream pixel component means that pixel component
+from first stream is returned unchanged, while maximum value (eg. 255 for
+8-bit videos) means that pixel component from second stream is returned
+unchanged. Intermediate values define the amount of merging between both
+input stream's pixel components.
+
+This filter accepts the following options:
+@table @option
+@item planes
+Set which planes will be processed as bitmap, unprocessed planes will be
+copied from first stream.
+By default value 0xf, all planes will be processed.
+@end table
+
 @section mergeplanes
 
 Merge color channel components from several video streams.

libavfilter/Makefile

@@ -169,6 +169,7 @@ OBJS-$(CONFIG_LUT3D_FILTER)                  += vf_lut3d.o
 OBJS-$(CONFIG_LUT_FILTER)                    += vf_lut.o
 OBJS-$(CONFIG_LUTRGB_FILTER)                 += vf_lut.o
 OBJS-$(CONFIG_LUTYUV_FILTER)                 += vf_lut.o
+OBJS-$(CONFIG_MASKEDMERGE_FILTER)            += vf_maskedmerge.o framesync.o
 OBJS-$(CONFIG_MCDEINT_FILTER)                += vf_mcdeint.o
 OBJS-$(CONFIG_MERGEPLANES_FILTER)            += vf_mergeplanes.o framesync.o
 OBJS-$(CONFIG_MPDECIMATE_FILTER)             += vf_mpdecimate.o

libavfilter/allfilters.c

@@ -191,6 +191,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(LUT,            lut,            vf);
     REGISTER_FILTER(LUTRGB,         lutrgb,         vf);
     REGISTER_FILTER(LUTYUV,         lutyuv,         vf);
+    REGISTER_FILTER(MASKEDMERGE,    maskedmerge,    vf);
     REGISTER_FILTER(MCDEINT,        mcdeint,        vf);
     REGISTER_FILTER(MERGEPLANES,    mergeplanes,    vf);
     REGISTER_FILTER(MPDECIMATE,     mpdecimate,     vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR   8
+#define LIBAVFILTER_VERSION_MINOR   9
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \