[FFmpeg-user] try to change complex filters on runtime

[lucie Lemonnier]

Hello, 
I want to change 
complex filters on runtime by changing the code of ffmpeg.c to change 
between different overlays or to change the value of x in crop 
parameters.
Before, i tried to change the overlays and crop with the 
use of simple filter.To try this, I call a fuction "filter_change" in 
the function transcode_step : 

void filter_change(char* newfilter){
               ost->avfilter = av_strdup(newfilter);
		if (configure_filtergraph(ost->filter->graph)) {
			av_log(NULL, AV_LOG_FATAL, "Error opening filters!\n");
			exit(1);
		}

}

I call for example : filter_change("movie = objets.png [mv1];[in][mv1] overlay=0:0 [out];[out] crop=1920:1080:0:0");
or 

filter_change("movie = transp.mov [mv1];[in][mv1] overlay=0:0 [out];[out] crop=1920:1080:0:0");
               

I
 use rtp to output. But when I add a video overlay for example, the 
output video (rtp) freeze and the output with overlay reappears after 5 
to 10 seconds. It's too long. I need a real-time change or almost.
That's why I test with complex filters.
I create a function reinit_filters_complex that I call in transcode_step :

void reinit_filters_complex(const char *arg){
	int i,j;
    for (i = 0; i < nb_filtergraphs; i++) {
        avfilter_graph_free(&filtergraphs[i]->graph);
        for (j = 0; j < filtergraphs[i]->nb_inputs; j++) {
            av_freep(&filtergraphs[i]->inputs[j]->name);
            av_freep(&filtergraphs[i]->inputs[j]);
        }
        av_freep(&filtergraphs[i]->inputs);
        for (j = 0; j < filtergraphs[i]->nb_outputs; j++) {
            av_freep(&filtergraphs[i]->outputs[j]->name);
            av_freep(&filtergraphs[i]->outputs[j]);
        }
        av_freep(&filtergraphs[i]->outputs);
        av_freep(&filtergraphs[i]);
    }
    av_freep(&filtergraphs);
	nb_filtergraphs = 0;
	GROW_ARRAY(filtergraphs, nb_filtergraphs);
	 if (!(filtergraphs[nb_filtergraphs - 1] = av_mallocz(sizeof(*filtergraphs[0]))))
        return AVERROR(ENOMEM);
    filtergraphs[nb_filtergraphs - 1]->index       = nb_filtergraphs - 1;
    filtergraphs[nb_filtergraphs - 1]->graph_desc = arg;

    configure_complex_filters();

}

For
 example , I call reinit_filters_complex("[0:0] crop=960:1080:0:0 
[tin];[2:0] crop=960:1080:0:0 [tmv]);[tin][tmv]overlay=0:0").
I 
passed in parameters of ffmpeg -i videoSource.mp4 -i transp.mov -i 
objets.png -filter_complex "[0:0] crop=960:1080:0:0 [tin];[1:0] 
crop=960:1080:0:0 [tmv]".
But It crash on this change.
I think it's because I free all in filtergraphs.
But I don't know what is missing for it to work.
Can you help me, please?
Thanks.