[FFmpeg-cvslog] avfilter/palettegen: allow a minimum of 2 colors

[Clément Bœsch]

ffmpeg | branch: master | Clément Bœsch <u at pkh.me> | Tue Dec 27 22:06:23 2022 +0100| [cad9d7fc85bde0b30823ae7b8ce17e97b6f7a387] | committer: Clément Bœsch

avfilter/palettegen: allow a minimum of 2 colors

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=cad9d7fc85bde0b30823ae7b8ce17e97b6f7a387
---

 libavfilter/vf_palettegen.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavfilter/vf_palettegen.c b/libavfilter/vf_palettegen.c
index 27f74fd147..c03f62b942 100644
--- a/libavfilter/vf_palettegen.c
+++ b/libavfilter/vf_palettegen.c
@@ -82,7 +82,7 @@ typedef struct PaletteGenContext {
 #define OFFSET(x) offsetof(PaletteGenContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 static const AVOption palettegen_options[] = {
-    { "max_colors", "set the maximum number of colors to use in the palette", OFFSET(max_colors), AV_OPT_TYPE_INT, {.i64=256}, 4, 256, FLAGS },
+    { "max_colors", "set the maximum number of colors to use in the palette", OFFSET(max_colors), AV_OPT_TYPE_INT, {.i64=256}, 2, 256, FLAGS },
     { "reserve_transparent", "reserve a palette entry for transparency", OFFSET(reserve_transparent), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, FLAGS },
     { "transparency_color", "set a background color for transparency", OFFSET(transparency_color), AV_OPT_TYPE_COLOR, {.str="lime"}, 0, 0, FLAGS },
     { "stats_mode", "set statistics mode", OFFSET(stats_mode), AV_OPT_TYPE_INT, {.i64=STATS_MODE_ALL_FRAMES}, 0, NB_STATS_MODE-1, FLAGS, "mode" },
@@ -586,6 +586,11 @@ static int init(AVFilterContext *ctx)
     if (s->use_alpha && s->reserve_transparent)
         s->reserve_transparent = 0;
 
+    if (s->max_colors - s->reserve_transparent < 2) {
+        av_log(ctx, AV_LOG_ERROR, "max_colors=2 is only allowed without reserving a transparent color slot\n");
+        return AVERROR(EINVAL);
+    }
+
     return 0;
 }