RRtpSession allows you to create a send stream. NewSendSourceL() creates a new send stream and returns a handle to RRtpSendStream. This is done only once per RTP session. If the send stream handle already exists, call SendSource() to get a handle to the send stream.
RRtpSendSource manages the creation and sending of RTP packets. A session can have only one send stream. At any point of time only one packet can be sent.