@@ -147,11 +147,15 @@ static int query_formats(AVFilterGraph *graph, AVClass *log_ctx)

                         return -1;

                     scale->filter->query_formats(scale);

-                    if(!avfilter_merge_formats(scale-> inputs[0]->in_formats,

-                                               scale-> inputs[0]->out_formats)||

-                       !avfilter_merge_formats(scale->outputs[0]->in_formats,

-                                               scale->outputs[0]->out_formats))

+                    if (((link = scale-> inputs[0]) &&

+                         !avfilter_merge_formats(link->in_formats, link->out_formats)) ||

+                        ((link = scale->outputs[0]) &&

+                         !avfilter_merge_formats(link->in_formats, link->out_formats))) {

+                        av_log(log_ctx, AV_LOG_ERROR,

+                               "Impossible to convert between the formats supported by the filter "

+                               "'%s' and the filter '%s'\n", link->src->name, link->dst->name);

                         return -1;

+                    }

                 }

             }

         }