[FFmpeg-devel] [PATCH v2 01/32] avfilter/palettegen: allow a minimum of 2 colors

[Clément Bœsch]

---
 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;
 }
 
-- 
2.39.0