SET_PARAMETER is simply *wrong*. Servers are not supposed to support except...

SET_PARAMETER is simply *wrong*. Servers are not supposed to support except for proprietary extensions (meaning we cannot use for just any random server).
Even GET_PARAMETER is hardly good, as it is not mandatory to implement either, but it is a defined way to ping (which SET_PARAMETER ain't).
In any case, the only proper way to ping a stream is RTCP feedback.
When it comes to the control session, better check OPTIONS Allow: header for GET_PARAMETER.

I really wonder how live555 can be so low-level though - smells like we are trying to be too intelligent here.

modules/demux/live555.cpp

@@ -1037,7 +1037,8 @@ static int Demux( demux_t *p_demux )
     /* Check if we need to send the server a Keep-A-Live signal */
     if( p_sys->b_timeout_call && p_sys->rtsp && p_sys->ms )
     {
-        p_sys->rtsp->setMediaSessionParameter( *p_sys->ms, "vlc" , "1" );
+        char *psz_bye = NULL;
+        p_sys->rtsp->getMediaSessionParameter( *p_sys->ms, NULL, psz_bye );
         p_sys->b_timeout_call = VLC_FALSE;
     }