d2dcfea052
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>