sub->rects = rects;
sub->end_display_time = FFMAX(sub->end_display_time, 10 * duration);
rects[sub->num_rects] = av_mallocz(sizeof(*rects[0]));
sub->rects = rects;
sub->end_display_time = FFMAX(sub->end_display_time, 10 * duration);
rects[sub->num_rects] = av_mallocz(sizeof(*rects[0]));