From cd4e6e404b4afdb4facffc85450c1dcd9abdfc5a Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Sun, 12 Sep 2021 17:03:38 +0200
Subject: [PATCH] avfilter/vf_extractplanes: fix regression

Report & solution provided by Andreas Rheinhardt.
---
 libavfilter/vf_extractplanes.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libavfilter/vf_extractplanes.c b/libavfilter/vf_extractplanes.c
index 111a132cad..6e7931b3e3 100644
--- a/libavfilter/vf_extractplanes.c
+++ b/libavfilter/vf_extractplanes.c
@@ -387,6 +387,7 @@ static av_cold int init_alphaextract(AVFilterContext *ctx)
     ExtractPlanesContext *s = ctx->priv;
 
     s->requested_planes = PLANE_A;
+    s->map[0] = 3;
 
     return 0;
 }