ECN capable transport with udpsink/src

[Samuel Hurst]

Hello,

Is there some non-obvious way to enable ECN with udpsink and/or udpsrc? 
I've found the qos-dscp parameter but that only sets the DS code point, 
not the two ECN bits in the IP header.

The reason for asking is that I'm interested in experimenting with ECN 
for RTP, as described in RFC 6679. I've tried manually adding some calls 
to g_socket_set_option and setting IP_RECVTOS and IP_TOS, but I'm not 
sure if this is just being swallowed by GSocket at the moment, as 
packets never seem to have the ECN-capable flag set on egress. I've 
validated with some other code that ECN does work on the network that 
I'm attempting to use.

Best regards,
-Sam