modules/video_output/opengl/sampler.c

@@ -436,7 +436,10 @@ opengl_init_swizzle(struct vlc_gl_sampler *sampler,
     else if (desc->plane_count == 2)
     {
         swizzle_per_tex[0] = "r";
-        swizzle_per_tex[1] = "rg";
+        if (oneplane_texfmt == GL_RED)
+            swizzle_per_tex[1] = "rg";
+        else
+            swizzle_per_tex[1] = "ra";
     }
     else if (desc->plane_count == 1)
     {