fate: add gradfun filter test.

tests/fate/filter.mak

@@ -48,6 +48,10 @@ FATE_HQDN3D += fate-filter-hqdn3d
 fate-filter-hqdn3d: CMD = framecrc -i $(SAMPLES)/smjpeg/scenwin.mjpg -vf hqdn3d -an
 FATE_FILTER-$(call ALLYES, SMJPEG_DEMUXER MJPEG_DECODER HQDN3D_FILTER) += $(FATE_HQDN3D)
 
+FATE_GRADFUN += fate-filter-gradfun
+fate-filter-gradfun: CMD = framecrc -i $(SAMPLES)/vmd/12.vmd -vf "sws_flags=+accurate_rnd+bitexact;gradfun=10:8" -an -frames:v 20
+FATE_FILTER-$(call ALLYES, VMD_DEMUXER VMDVIDEO_DECODER GRADFUN_FILTER) += $(FATE_GRADFUN)
+
 FATE_SAMPLES_AVCONV += $(FATE_FILTER-yes)
 
 #

tests/ref/fate/filter-gradfun

@@ -0,0 +1,21 @@
+#tb 0: 1/10
+0,          0,          0,        1,    76800, 0x441a686f
+0,          1,          1,        1,    76800, 0xfa354d07
+0,          2,          2,        1,    76800, 0x87222ea6
+0,          3,          3,        1,    76800, 0x36330279
+0,          4,          4,        1,    76800, 0x07cddd8c
+0,          5,          5,        1,    76800, 0x9c26b594
+0,          6,          6,        1,    76800, 0xf3a27e3e
+0,          7,          7,        1,    76800, 0x23df5149
+0,          8,          8,        1,    76800, 0xbc7e17e6
+0,          9,          9,        1,    76800, 0x3ab9e695
+0,         10,         10,        1,    76800, 0x793db568
+0,         11,         11,        1,    76800, 0xfd8f7a87
+0,         12,         12,        1,    76800, 0x20154d17
+0,         13,         13,        1,    76800, 0xb74c17f3
+0,         14,         14,        1,    76800, 0x9710e9e2
+0,         15,         15,        1,    76800, 0x02e1b96b
+0,         16,         16,        1,    76800, 0x580f8187
+0,         17,         17,        1,    76800, 0xb2d95790
+0,         18,         18,        1,    76800, 0x7ef121c8
+0,         19,         19,        1,    76800, 0xa30afa03