lavfi/avfiltergraph: improve error message in graph_check_validity()

Fix trac ticket #1944.

libavfilter/avfiltergraph.c

@@ -113,22 +113,25 @@ static int graph_check_validity(AVFilterGraph *graph, AVClass *log_ctx)
     int i, j;
 
     for (i = 0; i < graph->filter_count; i++) {
+        const AVFilterPad *pad;
         filt = graph->filters[i];
 
         for (j = 0; j < filt->nb_inputs; j++) {
             if (!filt->inputs[j] || !filt->inputs[j]->src) {
+                pad = &filt->input_pads[j];
                 av_log(log_ctx, AV_LOG_ERROR,
-                       "Input pad \"%s\" for the filter \"%s\" of type \"%s\" not connected to any source\n",
-                       filt->input_pads[j].name, filt->name, filt->filter->name);
+                       "Input pad \"%s\" with type %s of the filter instance \"%s\" of %s not connected to any source\n",
+                       pad->name, av_get_media_type_string(pad->type), filt->name, filt->filter->name);
                 return AVERROR(EINVAL);
             }
         }
 
         for (j = 0; j < filt->nb_outputs; j++) {
             if (!filt->outputs[j] || !filt->outputs[j]->dst) {
+                pad = &filt->output_pads[j];
                 av_log(log_ctx, AV_LOG_ERROR,
-                       "Output pad \"%s\" for the filter \"%s\" of type \"%s\" not connected to any destination\n",
-                       filt->output_pads[j].name, filt->name, filt->filter->name);
+                       "Output pad \"%s\" with type %s of the filter instance \"%s\" of %s not connected to any destination\n",
+                       pad->name, av_get_media_type_string(pad->type), filt->name, filt->filter->name);
                 return AVERROR(EINVAL);
             }
         }