fate: add a test for scale with variable input format.

tests/fate/avfilter.mak

@@ -27,6 +27,7 @@ FATE_LAVFI = fate-lavfi-alphaextract_rgb                                \
              fate-lavfi-pixfmts_vflip                                   \
              fate-lavfi-scale200                                        \
              fate-lavfi-scale500                                        \
+             fate-lavfi-scalenorm                                       \
              fate-lavfi-select                                          \
              fate-lavfi-setdar                                          \
              fate-lavfi-setsar                                          \

tests/lavfi-regression.sh

@@ -132,6 +132,7 @@ do_lavfi_lavd() {
 
 do_lavfi_lavd "life"                 "life=s=40x40:r=5:seed=42:mold=64" -t 2
 do_lavfi_lavd "testsrc"              "testsrc=r=7:n=2:d=10"
+do_lavfi_lavd "scalenorm"            "testsrc=s=128x96:d=1:r=5,format=yuv420p[a];testsrc=s=160x120:d=1:r=5[b];[a][b]concat=unsafe=1,scale=::sws_flags=+accurate_rnd+bitexact"
 
 # TODO: add tests for
 # direct rendering,

tests/ref/lavfi/scalenorm

+scalenorm           a6222528806dee9c438ce9a5f66220e4