Getting a black video on running a sample deepstream application

Hi Actually by reducing the bitrate to 2000 in sink1 the above warnings disappeared but I am still getting a black video as my output

And this warning comes in the begining :
** (deepstream-app:5471): CRITICAL **: gst_ffmpeg_cfg_set_property: assertion ‘qdata->size == sizeof (gint64)’ failed

Please suggest how to overcome this problem: