Trying to implement a Real Media specific way to set the bandwidth for a session (see attachments), I found the (to me) unsolvable problem to propagate the "bandwidth" parameter from a gstrtpsession to a specific extension.

At my ignorant eyes, it looks like rtsp extensions live by their own, not being aware neither of the pipeline they're working into nor of the rtspsrc element they're bound to. As a solution, I would propose to add a method to notify the extensions with at least a pointer to the latter.

Moreover, I found that as long as the rtspreal plugin is installed, any rtsp client based on GStreamer will expose itself as a RealMedia player.. pretty reductive, but it can probably be fixed with a fix in rtsp_ext_real_before_send to parse the URI and determine whether the stream has some probabilities to be powered by a real server before connecting to it. As it would be just an heuristic and very likely to fail in many cases, it would alternatively be good to allow gstrtspsrc to "probe" the server with a suitable method (OPTIONS?) and leave the extensions to process the OK response before altering what a client declares to be. In the case of rtspreal, it would probably require to send the OPTIONS twice, but imo it shouldn't require a modification in the design of the rtsp extensions.