Snippets collected/distilled from gists/blog posts/etc. Combined here for fellow web-searchers -- goal is to have an easy/minimal sink for in-app use, and then forward that stream in another process.
Read camera, push to UDP sink (usually from appsrc, here v4l2 camera):
$ gst-launch-1.0 -vvvv v4l2src ! 'video/x-raw, width=640, height=480, framerate=30/1' ! videoconvert ! x264enc pass=qual quantizer=20 tune=zerolatency ! rtph264pay ! udpsink port=1234
Visualize above:
$ gst-launch-1.0 -vvv udpsrc port=1234 ! "application/x-rtp,media=(string)video,clock-rate=(int)90000,encoding-name=(string)H264" ! rtph264depay ! h264parse ! decodebin ! videoconvert ! xvimagesink sync=false