avfilter/vf_frei0r: also set AVFilterLink.frame_rate

Signed-off-by: NMichael Niedermayer <michaelni@gmx.at>

libavfilter/vf_frei0r.c

@@ -471,6 +471,7 @@ static int source_config_props(AVFilterLink *outlink)
     outlink->w = s->w;
     outlink->h = s->h;
     outlink->time_base = s->time_base;
+    outlink->frame_rate = av_inv_q(s->time_base);
     outlink->sample_aspect_ratio = (AVRational){1,1};
 
     if (s->destruct && s->instance)