If collecting the backchannel stream after the stream has begun preparing, make sure to join it to the RTSP media bin, as is done for dynamic payloaders in the pad-added handler. Add a new internal stream creation method for it, that could be publically exposed later if it proves useful. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8378>
gst-rtsp-server is a library on top of GStreamer for building an RTSP server There are some examples in the examples/ directory and more comprehensive documentation in docs/README.