avfilter: add hqx filter (hq2x, hq3x, hq4x)

Partially fixes Ticket #3404 (xbr filter remaining)

Changelog

@@ -29,6 +29,7 @@ version <next>:
 - showcqt multimedia filter
 - zoompan filter
 - signalstats filter
+- hqx filter (hq2x, hq3x, hq4x)
 
 
 version 2.2:

MAINTAINERS

@@ -350,6 +350,7 @@ Filters:
   vf_drawbox.c/drawgrid                 Andrey Utkin
   vf_extractplanes.c                    Paul B Mahol
   vf_histogram.c                        Paul B Mahol
+  vf_hqx.c                              Clément Bœsch
   vf_il.c                               Paul B Mahol
   vf_mergeplanes.c                      Paul B Mahol
   vf_psnr.c                             Paul B Mahol

doc/filters.texi

@@ -5203,6 +5203,20 @@ A floating point number which specifies chroma temporal strength. It defaults to
 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}.
 @end table
 
+@section hqx
+
+Apply a high-quality magnification filter designed for pixel art. This filter
+was originally created by Maxim Stepin.
+
+It accepts the following option:
+
+@table @option
+@item n
+Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for
+@code{hq3x} and @code{4} for @code{hq4x}.
+Default is @code{3}.
+@end table
+
 @section hue
 
 Modify the hue and/or the saturation of the input.

libavfilter/Makefile

@@ -130,6 +130,7 @@ OBJS-$(CONFIG_HFLIP_FILTER)                  += vf_hflip.o
 OBJS-$(CONFIG_HISTEQ_FILTER)                 += vf_histeq.o
 OBJS-$(CONFIG_HISTOGRAM_FILTER)              += vf_histogram.o
 OBJS-$(CONFIG_HQDN3D_FILTER)                 += vf_hqdn3d.o
+OBJS-$(CONFIG_HQX_FILTER)                    += vf_hqx.o
 OBJS-$(CONFIG_HUE_FILTER)                    += vf_hue.o
 OBJS-$(CONFIG_IDET_FILTER)                   += vf_idet.o
 OBJS-$(CONFIG_IL_FILTER)                     += vf_il.o

libavfilter/allfilters.c

@@ -148,6 +148,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(HISTEQ,         histeq,         vf);
     REGISTER_FILTER(HISTOGRAM,      histogram,      vf);
     REGISTER_FILTER(HQDN3D,         hqdn3d,         vf);
+    REGISTER_FILTER(HQX,            hqx,            vf);
     REGISTER_FILTER(HUE,            hue,            vf);
     REGISTER_FILTER(IDET,           idet,           vf);
     REGISTER_FILTER(IL,             il,             vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   4
-#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, \

tests/fate/filter-video.mak

@@ -146,6 +146,13 @@ FATE_FILTER-$(call ALLYES, SMJPEG_DEMUXER MJPEG_DECODER PERMS_FILTER HQDN3D_FILT
 fate-filter-hqdn3d-sample: tests/data/filtergraphs/hqdn3d
 fate-filter-hqdn3d-sample: CMD = framecrc -idct simple -i $(TARGET_SAMPLES)/smjpeg/scenwin.mjpg -filter_complex_script $(TARGET_PATH)/tests/data/filtergraphs/hqdn3d -an
 
+FATE_FILTER_HQX-$(call ALLYES, IMAGE2_DEMUXER PNG_DECODER HQX_FILTER) = fate-filter-hq2x fate-filter-hq3x fate-filter-hq4x
+FATE_FILTER-yes += $(FATE_FILTER_HQX-yes)
+fate-filter-hq2x: CMD = framecrc -i $(TARGET_SAMPLES)/filter/pixelart%d.png -vf hqx=2
+fate-filter-hq3x: CMD = framecrc -i $(TARGET_SAMPLES)/filter/pixelart%d.png -vf hqx=3
+fate-filter-hq4x: CMD = framecrc -i $(TARGET_SAMPLES)/filter/pixelart%d.png -vf hqx=4
+fate-filter-hqx: $(FATE_FILTER_HQX-yes)
+
 FATE_FILTER-$(call ALLYES, UTVIDEO_DECODER AVI_DEMUXER PERMS_FILTER CURVES_FILTER) += fate-filter-curves
 fate-filter-curves: CMD = framecrc -i $(TARGET_SAMPLES)/utvideo/utvideo_rgb_median.avi -vf perms=random,curves=vintage
 

tests/ref/fate/filter-hq2x

+#tb 0: 1/25
+0,          0,          0,        1,   877072, 0x9369339e
+0,          1,          1,        1,   877072, 0x32d119a1

tests/ref/fate/filter-hq3x

+#tb 0: 1/25
+0,          0,          0,        1,  1973412, 0xafc227fa
+0,          1,          1,        1,  1973412, 0x93aebf19

tests/ref/fate/filter-hq4x

+#tb 0: 1/25
+0,          0,          0,        1,  3508288, 0x034ef75e
+0,          1,          1,        1,  3508288, 0x738e9bbb