Install callbacks that will be called when data for a stream should be sent to a client.
This is usually used when sending RTP/RTCP over TCP.
| this | |
| send_rtp |
a callback called when RTP should be sent |
| send_rtcp |
a callback called when RTCP should be sent |
| notify |
called with the user_data when no longer needed. |
| user_data |
user data passed to callbacks |