At the beginning I would like to connect small camera with PI3 only to check this part of configuration (using local area network). Next add pixhawk and modem and replace those part on my frame. Then I will be thinking about full telemetry but those 2 basic steps are the most important for me.
UAVcast using gStreamer to handle the video transmission. gStreamer does not support all usb cams. Im not familiar with the sj4000 type, and which format its streaming.
Do you see /dev/video0 in your RPI when it's connected?
If so, then type lsusb , and see if RPI is recognizing the camera. Also type dmesg and see the verbose output from RPI when usb cam is attached.
When i look at your gstreamer log, it looks like you are running gStreamer/UAVcast in PiCam mode? correct?
This wont work for USB cam. PiCam is used for the original Ribbon cameras .
Your best best is C920 or C615 for UAVcast, but i think it wont work.
You can find the UAVcast gStreamer pipelines here
Few years back i managed to stream video from GoPro cams in collaboration with USB Easycap device , but the lateancy was huge compared to C920 or PiCam. This way converts the AV to digital
What is the respons when typing in RPI shell and camera connected?
Just for your information, the pipeline i was using for easycap was
modprobe easycap 'bars=0'
v4l2-ctl -i 1
gst-launch-1.0 -v \
rtpbin name=rtpbin v4l2src device=/dev/video0 \
! video/x-raw,width=640,height=480,framerate=15/1 \
! queue \
! omxh264enc target-bitrate=900000 control-rate=3 \
! "video/x-h264,profile=high" \
! h264parse \
! queue max-size-bytes=10000000 \
! rtph264pay pt=96 config-interval=1 \
! rtpbin.send_rtp_sink_0 rtpbin.send_rtp_src_0 \
! udpsink port=5000 host=10.0.0.225 ts-offset=0 name=vrtpsink rtpbin.send_rtcp_src_0 \
! udpsink port=5001 host=10.0.0.225 sync=false async=false name=vrtcpsink udpsrc port=5000
name=vrtpsrc \ ! rtpbin.recv_rtcp_sink_0