lavfi: add LUT (LookUp Table) generic filters

Signed-off-by: Anton Khirnov <anton@khirnov.net>

Changelog

@@ -50,6 +50,7 @@ easier to use. The changes are:
 - Apple ProRes decoder
 - CELT in Ogg demuxing
 - VC-1 interlaced decoding
+- lut, lutrgb, and lutyuv filters
 
 
 version 0.7:

doc/filters.texi

@@ -701,6 +701,118 @@ a float number which specifies chroma temporal strength, defaults to
 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
 @end table
 
+@section lut, lutrgb, lutyuv
+
+Compute a look-up table for binding each pixel component input value
+to an output value, and apply it to input video.
+
+@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
+to an RGB input video.
+
+These filters accept in input a ":"-separated list of options, which
+specify the expressions used for computing the lookup table for the
+corresponding pixel component values.
+
+The @var{lut} filter requires either YUV or RGB pixel formats in
+input, and accepts the options:
+@table @option
+@var{c0} (first  pixel component)
+@var{c1} (second pixel component)
+@var{c2} (third  pixel component)
+@var{c3} (fourth pixel component, corresponds to the alpha component)
+@end table
+
+The exact component associated to each option depends on the format in
+input.
+
+The @var{lutrgb} filter requires RGB pixel formats in input, and
+accepts the options:
+@table @option
+@var{r} (red component)
+@var{g} (green component)
+@var{b} (blue component)
+@var{a} (alpha component)
+@end table
+
+The @var{lutyuv} filter requires YUV pixel formats in input, and
+accepts the options:
+@table @option
+@var{y} (Y/luminance component)
+@var{u} (U/Cb component)
+@var{v} (V/Cr component)
+@var{a} (alpha component)
+@end table
+
+The expressions can contain the following constants and functions:
+
+@table @option
+@item E, PI, PHI
+the corresponding mathematical approximated values for e
+(euler number), pi (greek PI), PHI (golden ratio)
+
+@item w, h
+the input width and heigth
+
+@item val
+input value for the pixel component
+
+@item clipval
+the input value clipped in the @var{minval}-@var{maxval} range
+
+@item maxval
+maximum value for the pixel component
+
+@item minval
+minimum value for the pixel component
+
+@item negval
+the negated value for the pixel component value clipped in the
+@var{minval}-@var{maxval} range , it corresponds to the expression
+"maxval-clipval+minval"
+
+@item clip(val)
+the computed value in @var{val} clipped in the
+@var{minval}-@var{maxval} range
+
+@item gammaval(gamma)
+the computed gamma correction value of the pixel component value
+clipped in the @var{minval}-@var{maxval} range, corresponds to the
+expression
+"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
+
+@end table
+
+All expressions default to "val".
+
+Some examples follow:
+@example
+# negate input video
+lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
+lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
+
+# the above is the same as
+lutrgb="r=negval:g=negval:b=negval"
+lutyuv="y=negval:u=negval:v=negval"
+
+# negate luminance
+lutyuv=negval
+
+# remove chroma components, turns the video into a graytone image
+lutyuv="u=128:v=128"
+
+# apply a luma burning effect
+lutyuv="y=2*val"
+
+# remove green and blue components
+lutrgb="g=0:b=0"
+
+# set a constant alpha channel value on input
+format=rgba,lutrgb=a="maxval-minval/2"
+
+# correct luminance gamma by a 0.5 factor
+lutyuv=y=gammaval(0.5)
+@end example
+
 @section noformat
 
 Force libavfilter not to use any of the specified pixel formats for the

libavfilter/Makefile

@@ -33,6 +33,9 @@ OBJS-$(CONFIG_FREI0R_FILTER)                 += vf_frei0r.o
 OBJS-$(CONFIG_GRADFUN_FILTER)                += vf_gradfun.o
 OBJS-$(CONFIG_HFLIP_FILTER)                  += vf_hflip.o
 OBJS-$(CONFIG_HQDN3D_FILTER)                 += vf_hqdn3d.o
+OBJS-$(CONFIG_LUT_FILTER)                    += vf_lut.o
+OBJS-$(CONFIG_LUTRGB_FILTER)                 += vf_lut.o
+OBJS-$(CONFIG_LUTYUV_FILTER)                 += vf_lut.o
 OBJS-$(CONFIG_NOFORMAT_FILTER)               += vf_format.o
 OBJS-$(CONFIG_NULL_FILTER)                   += vf_null.o
 OBJS-$(CONFIG_OCV_FILTER)                    += vf_libopencv.o

libavfilter/allfilters.c

@@ -54,6 +54,9 @@ void avfilter_register_all(void)
     REGISTER_FILTER (GRADFUN,     gradfun,     vf);
     REGISTER_FILTER (HFLIP,       hflip,       vf);
     REGISTER_FILTER (HQDN3D,      hqdn3d,      vf);
+    REGISTER_FILTER (LUT,         lut,         vf);
+    REGISTER_FILTER (LUTRGB,      lutrgb,      vf);
+    REGISTER_FILTER (LUTYUV,      lutyuv,      vf);
     REGISTER_FILTER (NOFORMAT,    noformat,    vf);
     REGISTER_FILTER (NULL,        null,        vf);
     REGISTER_FILTER (OCV,         ocv,         vf);

libavfilter/avfilter.h

@@ -29,8 +29,8 @@
 #include "libavutil/rational.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  2
-#define LIBAVFILTER_VERSION_MINOR  7
-#define LIBAVFILTER_VERSION_MICRO  2
+#define LIBAVFILTER_VERSION_MINOR  8
+#define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \

libavfilter/formats.c

@@ -21,6 +21,7 @@
 
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
+#include "internal.h"
 
 /**
  * Add all refs from a to ret and destroy a.
@@ -70,6 +71,17 @@ AVFilterFormats *avfilter_merge_formats(AVFilterFormats *a, AVFilterFormats *b)
     return ret;
 }
 
+int ff_fmt_is_in(int fmt, const int *fmts)
+{
+    const int *p;
+
+    for (p = fmts; *p != PIX_FMT_NONE; p++) {
+        if (fmt == *p)
+            return 1;
+    }
+    return 0;
+}
+
 AVFilterFormats *avfilter_make_format_list(const int *fmts)
 {
     AVFilterFormats *formats;

libavfilter/internal.h

@@ -52,4 +52,7 @@ int ff_avfilter_graph_config_formats(AVFilterGraph *graphctx, AVClass *log_ctx);
 /** default handler for freeing audio/video buffer when there are no references left */
 void ff_avfilter_default_free_buffer(AVFilterBuffer *buf);
 
+/** Tell is a format is contained in the provided list terminated by -1. */
+int ff_fmt_is_in(int fmt, const int *fmts);
+
 #endif /* AVFILTER_INTERNAL_H */