[FFmpeg-user] Filters and chains

[JULIAN GARDNER]

Im trying to walk the filtergraphs chain using code to see what is happening
    for (i = 0; i < nb_filtergraphs; i++) {
    FilterGraph *fg = filtergraphs[i];
    int j;

        av_log( NULL, AV_LOG_WARNING, "Filter %3d %s [%d, %d]\n",
            fg->index, fg->graph_desc, fg->nb_inputs, fg->nb_outputs);

        for (j = 0; j < fg->nb_inputs; j++) {
            av_log( NULL, AV_LOG_WARNING, "  Input  %3d %s\n",
                j, fg->inputs[j]->name);
        }
        for(j = 0; j < fg->nb_outputs; j++) {
            av_log( NULL, AV_LOG_WARNING, "  Output %3d %s\n",
                j, fg->outputs[j]->name);
        }
    }

Now with this simple filter'scale=640:360,delogo=100:100:100:100,drawbox=10:10:16:9:4:color=yellow'
I get
Filter   0 scale=640:360,delogo=100:100:100:100,drawbox=10:10:16:9:4:color=yellow [1, 1]
  Input    0 scale
  Output   0 drawbox
Filter   1 (null) [1, 1]
  Input    0 (null)
  Output   0 (null)

Where is the delogo, is there another chain i need to walk?
joolz