[Live-devel] RTCP: Changing RR packets receptions interval.

[Ross Finlayson]

> Is there any way, from the source side, to change the frequency of reception of the RR packets.

I presume that what you’re really asking is “How can you control the rate at which media receivers (e.g., RTSP clients) *send* RTCP RR packets?”

Endpoints send RTCP packets in accordance with the rules/algorithm specified in RFC 3550.  Our code implements this automatically, based on its estimate of the media’s bandwidth.  Programmers that use the LIVE555 library do not send RTCP RR or SR packets explicitly; instead, our library code does this automatically.  Therefore, for our code, your question reduces to: “How can you tell media receivers the estimated bandwidth of the stream?”.

This is done using the “b=AS:<bitrate-in-kbps>” line in the media’s SDP description (which RTSP clients receive when they perform a RTSP “DESCRIBE” operation).

If the SDP description does not contain a "b=AS:” line, then our client code will assume a bitrate of 500 kbps.

However, our RTSP server code will automatically include a “b=AS:” line in the SDP descriptions that it generates for each media stream (using the “estBitrate” result parameter from the call to the “createNewStreamSource()” virtual function.  Therefore, if the stream’s server is using our RTSP server implementation, then the proper bitrate should be passed to each RTSP client, and it will then send RTCP RR packets at the proper rate.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/