SRT Connection Mode Examples

In Figure 8 below, the SRT source device is in Caller mode, and the SRT destination device is in Listener mode. The SRT source (Caller) initiates the handshake by sending a series of control packets in a UDP stream (1). When the SRT destination (Listener) receives these control packets, it responds by sending its own (2). Once the handshake has successfully completed, the SRT source device begins adding media packets to the UDP stream (3).

Figure 8 – SRT source device initiates connection

Note

Regardless of which device is in which mode, when the SRT handshake is completed both source and destination continue to exchange control packets containing information about network conditions, dropped packets, etc. Once communication is established, the notion of which device is Caller and which is Listener becomes unimportant. What matters is the source/destination relationship, which is decoupled from the caller/listener relationship.

In Figure 9 below, the roles are reversed — the SRT source device is in Listener mode, and the SRT destination device is in Caller mode. The SRT destination (Caller) initiates the handshake by sending a series of control packets in a UDP stream (1). When the SRT source (Listener) receives these control packets, it responds by sending its own (2). Once the handshake has successfully completed, the SRT source device begins adding media packets to the UDP stream (3).

Figure 9 – SRT destination device initiates connection

In Figure 10 below, both the SRT source device and the SRT destination device are in Rendezvous mode. Both devices send a series of control packets in a UDP stream (1). Once the handshake has successfully completed, the SRT source device begins adding media packets to the UDP stream (2).

Figure 10 — SRT connection initiated using Rendezvous