lavfi: add psnr filter

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

Changelog

@@ -69,6 +69,7 @@ version <next>:
 - rotate filter
 - spp filter ported from libmpcodecs
 - libgme support
+- psnr filter
 
 
 version 1.2:

doc/filters.texi

@@ -5837,6 +5837,79 @@ pp=hb|y/vb|a
 @end example
 @end itemize
 
+@section psnr
+
+Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
+Ratio) between two input videos.
+
+This filter takes in input two input videos, the first input is
+considered the "main" source and is passed unchanged to the
+output. The second input is used as a "reference" video for computing
+the PSNR.
+
+Both video inputs 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 average PSNR is printed through the logging system.
+
+The filter stores the accumulated MSE (mean squared error) of each
+frame, and at the end of the processing it is averaged across all frames
+equally, and the following formula is applied to obtain the PSNR:
+
+@example
+PSNR = 10*log10(MAX^2/MSE)
+@end example
+
+Where MAX is the average of the maximum values of each component of the
+image.
+
+The filter accepts parameters as a list of @var{key}=@var{value} pairs,
+separated by ":".
+
+The description of the accepted parameters follows.
+
+@table @option
+@item stats_file, f
+If specified the filter will use the named file to save the PSNR of
+each individual frame.
+@end table
+
+The file printed if @var{stats_file} is selected, contains a sequence of
+key/value pairs of the form @var{key}:@var{value} for each compared
+couple of frames.
+
+The shown line contains .
+
+A description of each shown parameter follows:
+
+@table @option
+@item n
+sequential number of the input frame, starting from 1
+
+@item mse_average
+Mean Square Error pixel-by-pixel average difference of the compared
+frames, averaged over all the image components.
+
+@item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a
+Mean Square Error pixel-by-pixel average difference of the compared
+frames for the component specified by the suffix.
+
+@item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_g, psnr_a
+Peak Signal to Noise ratio of the compared frames for the component
+specified by the suffix.
+@end table
+
+For example:
+@example
+movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
+[main][ref] psnr="stats_file=stats.log" [out]
+@end example
+
+On this example the input file being processed is compared with the
+reference file @file{ref_movie.mpg}. The PSNR of each individual frame
+is stored in @file{stats.log}.
+
 @section removelogo
 
 Suppress a TV station logo, using an image file to determine which

libavfilter/Makefile

@@ -167,6 +167,7 @@ OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o
 OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o
 OBJS-$(CONFIG_PIXDESCTEST_FILTER)            += vf_pixdesctest.o
 OBJS-$(CONFIG_PP_FILTER)                     += vf_pp.o
+OBJS-$(CONFIG_PSNR_FILTER)                   += vf_psnr.o dualinput.o
 OBJS-$(CONFIG_REMOVELOGO_FILTER)             += bbox.o lswsutils.o lavfutils.o vf_removelogo.o
 OBJS-$(CONFIG_ROTATE_FILTER)                 += vf_rotate.o
 OBJS-$(CONFIG_SEPARATEFIELDS_FILTER)         += vf_separatefields.o

libavfilter/allfilters.c

@@ -162,6 +162,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(PERMS,          perms,          vf);
     REGISTER_FILTER(PIXDESCTEST,    pixdesctest,    vf);
     REGISTER_FILTER(PP,             pp,             vf);
+    REGISTER_FILTER(PSNR,           psnr,           vf);
     REGISTER_FILTER(REMOVELOGO,     removelogo,     vf);
     REGISTER_FILTER(ROTATE,         rotate,         vf);
     REGISTER_FILTER(SAB,            sab,            vf);

libavfilter/version.h

@@ -30,8 +30,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  78
-#define LIBAVFILTER_VERSION_MICRO 103
+#define LIBAVFILTER_VERSION_MINOR  79
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \