avfilter: add corr video filter

Changelog

@@ -26,6 +26,7 @@ version <next>:
 - QSV AV1 encoder
 - QSV decoding and encoding for 10/12bit 422, 10/12bit 444 HEVC and VP9
 - showcwt multimedia filter
+- corr video filter
 
 
 version 5.1:

doc/filters.texi

@@ -10110,6 +10110,30 @@ ffmpeg -f lavfi -i nullsrc=s=100x100,coreimage=filter=CIQRCodeGenerator@@inputMe
 @end example
 @end itemize
 
+@section corr
+
+Obtain the correlation between two input videos.
+
+This filter takes two input videos.
+
+Both input videos must have the same resolution and pixel format for
+this filter to work correctly. Also it assumes that both inputs
+have the same number of frames, which are compared one by one.
+
+The obtained per component, average, min and max correlation is printed through
+the logging system.
+
+The filter stores the calculated correlation of each frame in frame metadata.
+
+This filter also supports the @ref{framesync} options.
+
+In the below example the input file @file{main.mpg} being processed is compared
+with the reference file @file{ref.mpg}.
+
+@example
+ffmpeg -i main.mpg -i ref.mpg -lavfi corr -f null -
+@end example
+
 @section cover_rect
 
 Cover a rectangular object

libavfilter/Makefile

@@ -241,6 +241,7 @@ OBJS-$(CONFIG_CONVOLUTION_OPENCL_FILTER)     += vf_convolution_opencl.o opencl.o
 OBJS-$(CONFIG_CONVOLVE_FILTER)               += vf_convolve.o framesync.o
 OBJS-$(CONFIG_COPY_FILTER)                   += vf_copy.o
 OBJS-$(CONFIG_COREIMAGE_FILTER)              += vf_coreimage.o
+OBJS-$(CONFIG_CORR_FILTER)                   += vf_corr.o framesync.o
 OBJS-$(CONFIG_COVER_RECT_FILTER)             += vf_cover_rect.o lavfutils.o
 OBJS-$(CONFIG_CROP_FILTER)                   += vf_crop.o
 OBJS-$(CONFIG_CROPDETECT_FILTER)             += vf_cropdetect.o

libavfilter/allfilters.c

@@ -221,6 +221,7 @@ extern const AVFilter ff_vf_convolution_opencl;
 extern const AVFilter ff_vf_convolve;
 extern const AVFilter ff_vf_copy;
 extern const AVFilter ff_vf_coreimage;
+extern const AVFilter ff_vf_corr;
 extern const AVFilter ff_vf_cover_rect;
 extern const AVFilter ff_vf_crop;
 extern const AVFilter ff_vf_cropdetect;

libavfilter/version.h

@@ -31,7 +31,7 @@
 
 #include "version_major.h"
 
-#define LIBAVFILTER_VERSION_MINOR  51
+#define LIBAVFILTER_VERSION_MINOR  52
 #define LIBAVFILTER_VERSION_MICRO 100