Ok. I have solved my problem.
I’m using Ardupilot_sitl and I could not find anything in ardupilot sitl that referenced video streaming.
There is a gazebo plugin that I found available in PX4_sitl
So this is how I accessed it for use in gazebo/ardupilot_sitl
git clone https://github.com/PX4/PX4-Autopilot.git --recursive
Edit the build.sh file to get gazebo9 it changes depending on ubuntu version.
Later ubuntu versions will automatically want to build for gazebo11 etc
But we need a build for gazebo9 (or whatever you are running).
So edit to fix, then run
bash ./PX4-Autopilot/Tools/setup/ubuntu.sh —no-nuttx
Once build we need some plugins compiled which will only be compiled
for certain models - in this case the typhoon_h480 model
make px4_sitl gazebo_typhoon_h480
This will start gazebo with that model, just exit.
You’ll find a bunch of plugins. You can either change your env variable to add this directory or
copy the ones you want to use to the place where gazebo looks for its plugins.
You’ll be interested in:
libgazebo_camera_manager_plugin.so -- if you want to control from QGroundControl
In the your model.sdf where you have the vehicle camera you should add"
<plugin name="GstCameraPlugin" filename="libgazebo_gst_camera_plugin.so">
In the .world that you are invoking add:
<plugin name="video_widget" filename="libgazebo_video_stream_widget.so"/>
This will make a gui button appear that allows you to stop start the video stream. Default is on.
If you are looking to add the camera manager plugin so that you can control the video feed with QGroundControl see the typhoon_h480.sdf for an example. I didn’t need this feature so I have not tested it.
Once you start gazebo with the above changes check that you have no errors and that the plugins have been found.
Then you can start a gstreamer pipeline to display the video,e.g.
gst-launch-1.0 -v udpsrc port=5600 caps='application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264' \
! rtph264depay ! avdec_h264 ! videoconvert ! autovideosink fps-update-interval=1000 sync=false
Where port is the same as what you specified in the plugin .sdf. Its sending RTP with the video encoded as H264. You can do anything you want with it that a gstreamer pipeline allows.
Note: none of this is directly related to Ardupilot sitl since the camera and the plugin that streams are independent of ardupilot_sitl. However it appears to be a common need - based on previous unanswered questions. So I have posted here.
I even managed to confuse myself on this topic because the plugin was found in the sitl for PX4
You can find more background details at Gazebo Simulation | PX4 User Guide