vf_scale: support PAL8 output by producing BGR8.

While quality is bad, PAL8 support is needed to allow testing some
encoders that only support PAL8 input.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavfilter/vf_scale.c

@@ -128,7 +128,7 @@ static int query_formats(AVFilterContext *ctx)
     if (ctx->outputs[0]) {
         formats = NULL;
         for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)
-            if (    sws_isSupportedOutput(pix_fmt)
+            if (   (sws_isSupportedOutput(pix_fmt) || pix_fmt == PIX_FMT_PAL8)
                 && (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {
                 avfilter_formats_unref(&formats);
                 return ret;
@@ -143,6 +143,7 @@ static int config_props(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AVFilterLink *inlink = outlink->src->inputs[0];
+    enum PixelFormat outfmt = outlink->format;
     ScaleContext *scale = ctx->priv;
     int64_t w, h;
     double var_values[VARS_NB], res;
@@ -212,21 +213,22 @@ static int config_props(AVFilterLink *outlink)
            scale->flags);
 
     scale->input_is_pal = av_pix_fmt_descriptors[inlink->format].flags & PIX_FMT_PAL;
+    if (outfmt == PIX_FMT_PAL8) outfmt = PIX_FMT_BGR8;
 
     if (scale->sws)
         sws_freeContext(scale->sws);
     scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
-                                outlink->w, outlink->h, outlink->format,
+                                outlink->w, outlink->h, outfmt,
                                 scale->flags, NULL, NULL, NULL);
     if (scale->isws[0])
         sws_freeContext(scale->isws[0]);
     scale->isws[0] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,
-                                    outlink->w, outlink->h/2, outlink->format,
+                                    outlink->w, outlink->h/2, outfmt,
                                     scale->flags, NULL, NULL, NULL);
     if (scale->isws[1])
         sws_freeContext(scale->isws[1]);
     scale->isws[1] = sws_getContext(inlink ->w, inlink ->h/2, inlink ->format,
-                                    outlink->w, outlink->h/2, outlink->format,
+                                    outlink->w, outlink->h/2, outfmt,
                                     scale->flags, NULL, NULL, NULL);
     if (!scale->sws || !scale->isws[0] || !scale->isws[1])
         return AVERROR(EINVAL);

tests/ref/lavfi/pixfmts_copy

@@ -20,6 +20,7 @@ monob               668ebe8b8103b9046b251b2fa8a1d88f
 monow               9251497f3b0634f1165d12d5a289d943
 nv12                e0af357888584d36eec5aa0f673793ef
 nv21                9a3297f3b34baa038b1f37cb202b512f
+pal8                dec8ed2258ec89b8a796f21cad4df867
 rgb0                ff1a9f355d43f9d25f07a191b5aa906c
 rgb24               b41eba9651e1b5fe386289b506188105
 rgb48be             cc139ec1dd9451f0e049c0cb3a0c8aa2

tests/ref/lavfi/pixfmts_crop

@@ -13,6 +13,7 @@ bgra                395c9f706fccda721471acaa5c96c16c
 gray                8c4850e66562a587a292dc728a65ea4a
 gray16be            257b4339925b0e672f552d8c9511f2c3
 gray16le            67cf7b26cda55356cc25e0f4e42cc136
+pal8                d6c1b598244f41e2f005e42407d234d2
 rgb24               3b90ed64b687d3dc186c6ef521dc71a8
 rgb48be             e6fd353c0eb9bea889423954414bea35
 rgb48le             68a1723da11ce08b502d42e204376503

tests/ref/lavfi/pixfmts_hflip

@@ -13,6 +13,7 @@ bgra                01ca21e7e6a8d1281b4553bde8e8a404
 gray                03efcb4ab52a24c0af0e03cfd26c9377
 gray16be            632535b46edec78a6534ef18d37f2b71
 gray16le            5c24e6f847bf9a41a40760c0d15df161
+pal8                6c1545bb295e9289add1760851a3d9c9
 rgb24               754f1722fc738590cc407ac65749bfe8
 rgb48be             d690412ca5fada031b5da47b87096248
 rgb48le             c901feb564232f5d0bc0eabd66dae3e7

tests/ref/lavfi/pixfmts_null

@@ -20,6 +20,7 @@ monob               668ebe8b8103b9046b251b2fa8a1d88f
 monow               9251497f3b0634f1165d12d5a289d943
 nv12                e0af357888584d36eec5aa0f673793ef
 nv21                9a3297f3b34baa038b1f37cb202b512f
+pal8                dec8ed2258ec89b8a796f21cad4df867
 rgb0                ff1a9f355d43f9d25f07a191b5aa906c
 rgb24               b41eba9651e1b5fe386289b506188105
 rgb48be             cc139ec1dd9451f0e049c0cb3a0c8aa2

tests/ref/lavfi/pixfmts_scale

@@ -20,6 +20,7 @@ monob               cb62f31b701c6e987b574974d1b31e32
 monow               fd5d417ab7728acddffc06870661df61
 nv12                4676d59db43d657dc12841f6bc3ab452
 nv21                69c699510ff1fb777b118ebee1002f14
+pal8                6324fa058e1bc157ed7132bfe4022317
 rgb0                1bd6f54ad067503ac9783a70062c8f87
 rgb24               13ff53ebeab74dc05492836f1cfbd2c1
 rgb48be             8fac63787a711886030f8e056872b488

tests/ref/lavfi/pixfmts_vflip

@@ -20,6 +20,7 @@ monob               d0cf8732677a5360b6160133043590d8
 monow               ff9869d067ecb94eb9d90c9750c31fea
 nv12                046f00f598ce14d9854a3534a5c99114
 nv21                01ea369dd2d0d3ed7451dc5c8d61497f
+pal8                47ed19a7e128b0e33c25d2a463b0611a
 rgb0                330bd6168e46c0d5eb4acbdbb50afa2e
 rgb24               eaefabc168d0b14576bab45bc1e56e1e
 rgb48be             62dd185862ed142283bd300eb6dbd216