vf_scale: ensure the palette is set for output.

Since those are pseudo-palette formats, swscale does not write
into data[1], swscale must initialize the palette properly itself.
This lead to frames that actually decoded as all-gray before.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavfilter/vf_scale.c

@@ -28,6 +28,7 @@
 #include "libavutil/eval.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/pixdesc.h"
+#include "libavutil/imgutils.h"
 #include "libavutil/avassert.h"
 #include "libswscale/swscale.h"
 
@@ -279,6 +280,8 @@ static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
     outpicref->video->h = outlink->h;
 
     outlink->out_buf = outpicref;
+    if(scale->output_is_pal)
+        ff_set_systematic_pal2(outpicref->data[1], outlink->format == PIX_FMT_PAL8 ? PIX_FMT_BGR8 : outlink->format);
 
     av_reduce(&outpicref->video->sample_aspect_ratio.num, &outpicref->video->sample_aspect_ratio.den,
               (int64_t)picref->video->sample_aspect_ratio.num * outlink->h * link->w,

tests/ref/lavfi/pixfmts_crop

@@ -13,7 +13,7 @@ bgra                395c9f706fccda721471acaa5c96c16c
 gray                8c4850e66562a587a292dc728a65ea4a
 gray16be            257b4339925b0e672f552d8c9511f2c3
 gray16le            67cf7b26cda55356cc25e0f4e42cc136
-pal8                d6c1b598244f41e2f005e42407d234d2
+pal8                0a7c8a7029b77619a6d847cf6f6ad0ac
 rgb24               3b90ed64b687d3dc186c6ef521dc71a8
 rgb48be             e6fd353c0eb9bea889423954414bea35
 rgb48le             68a1723da11ce08b502d42e204376503

tests/ref/lavfi/pixfmts_null

@@ -22,7 +22,7 @@ monob               668ebe8b8103b9046b251b2fa8a1d88f
 monow               9251497f3b0634f1165d12d5a289d943
 nv12                e0af357888584d36eec5aa0f673793ef
 nv21                9a3297f3b34baa038b1f37cb202b512f
-pal8                dec8ed2258ec89b8a796f21cad4df867
+pal8                09b4a6a3167576627fe0540994c3eb24
 rgb0                1ed8e8027126d283e6ed7359e81c56e4
 rgb24               b41eba9651e1b5fe386289b506188105
 rgb444be            9e89db334568c6b2e3d5d0540f4ba960

tests/ref/lavfi/pixfmts_scale

@@ -22,7 +22,7 @@ monob               cb62f31b701c6e987b574974d1b31e32
 monow               fd5d417ab7728acddffc06870661df61
 nv12                4676d59db43d657dc12841f6bc3ab452
 nv21                69c699510ff1fb777b118ebee1002f14
-pal8                6324fa058e1bc157ed7132bfe4022317
+pal8                0e7e9aee9f4f02f50cb72bee640843df
 rgb0                a01995946117e77b20e851506d64688c
 rgb24               13ff53ebeab74dc05492836f1cfbd2c1
 rgb444be            46e466b2709f62b2fffc63708063eaaf

tests/ref/lavfi/pixfmts_vflip

@@ -22,7 +22,7 @@ monob               d0cf8732677a5360b6160133043590d8
 monow               ff9869d067ecb94eb9d90c9750c31fea
 nv12                046f00f598ce14d9854a3534a5c99114
 nv21                01ea369dd2d0d3ed7451dc5c8d61497f
-pal8                47ed19a7e128b0e33c25d2a463b0611a
+pal8                f20e2ccf7e884d31a6766d45a73c2cdf
 rgb0                972c4ed97786aa30b7137b083b0e0afc
 rgb24               eaefabc168d0b14576bab45bc1e56e1e
 rgb444be            06722e03f8404e7d2226665ed2444a32

tests/ref/vsynth1/zmbv

 5112508 ./tests/data/vsynth1/zmbv.avi
-cfbec364e41d70c9b177435b5655d8af *./tests/data/zmbv.vsynth1.out.yuv
-stddev:   46.47 PSNR: 14.79 MAXDIFF:  129 bytes:  7603200/  7603200
+4ad1ca9de7c65eab68a619c54fffaec8 *./tests/data/zmbv.vsynth1.out.yuv
+stddev:    8.61 PSNR: 29.43 MAXDIFF:   64 bytes:  7603200/  7603200

tests/ref/vsynth2/zmbv

 5116352 ./tests/data/vsynth2/zmbv.avi
-cfbec364e41d70c9b177435b5655d8af *./tests/data/zmbv.vsynth2.out.yuv
-stddev:   42.07 PSNR: 15.65 MAXDIFF:  112 bytes:  7603200/  7603200
+ee68a5292fd0745834246b4ec0d85e9b *./tests/data/zmbv.vsynth2.out.yuv
+stddev:    8.12 PSNR: 29.94 MAXDIFF:   32 bytes:  7603200/  7603200