hevc_nal: return only valid framerate

modules/packetizer/hevc_nal.c

@@ -1034,14 +1034,14 @@ bool hevc_get_frame_rate( const hevc_sequence_parameter_set_t *p_sps,
     {
         *pi_den = p_sps->vui.timing.vui_num_units_in_tick;
         *pi_num = p_sps->vui.timing.vui_time_scale;
-        return true;
+        return (*pi_den && *pi_num);
     }
     else if( pp_vps && pp_vps[p_sps->sps_video_parameter_set_id] &&
              pp_vps[p_sps->sps_video_parameter_set_id]->vps_timing_info_present_flag )
     {
         *pi_den = pp_vps[p_sps->sps_video_parameter_set_id]->vps_num_units_in_tick;
         *pi_num = pp_vps[p_sps->sps_video_parameter_set_id]->vps_time_scale;
-        return true;
+        return (*pi_den && *pi_num);
     }
     return false;
 }