omxh264enc and nvvidconv NOT working unless...

Hi,
We follow this page to add /etc/systemd/system/rc-local.service

and add /etc/rc.local

#!/bin/bash

/usr/bin/gst-launch-1.0 v4l2src device=/dev/video1 num-buffers=300 ! video/x-raw,width=1920,height=1080,framerate=30/1,format=UYVY ! queue max-size-time=0 ! nvvidconv ! 'video/x-raw(memory:NVMM)' ! omxh264enc bitrate=5000000 ! video/x-h264 ! h264parse ! video/x-h264 ! queue ! flvmux name=mux streamable=true ! filesink location=/tmp/a.flv audiotestsrc num-buffers=500 ! queue ! audioconvert ! audioresample ! audio/x-raw,rate=44100 ! voaacenc bitrate=128000 ! audio/mpeg ! aacparse ! audio/mpeg, mpegversion=4 ! mux.

We can get a valid /tmp/a.flv. The USB camera used in the test is See3CAM CU135. FYR.