Source & Destination

The SRT protocol relies on bi-directional UDP traffic to optimize video streaming over public networks. In addition to the video data that is sent from a content source device (such as a Makito X Encoder) to a destination (such as a Makito X Decoder), there is a constant exchange of control information between the two endpoints, including “keep alive” packets (if needed) approximately every 10 ms, which enable SRT streams to be automatically restored after a connection loss.

Note

It is important to understand that with an SRT stream, the source is the device that is sending the content (audio and/or video data), while the destination is the device receiving the content. Elsewhere, you may encounter references to an SRT sender and an SRT receiver, but to avoid confusion in this document we will be using the terms source and destination.

In some cases, a device can act as both the source and the destination. For example, a Haivision Media Gateway may act as a destination while receiving an SRT stream from a Makito X Encoder, and then become a source device as it re-streams to a Makito X Decoder.*

* There is room for confusion inherent in discussions of SRT, where the terms “caller/listener”, “sender/receiver”, and “source/destination” often appear. But “caller/listener” has no direct correspondence with “source/destination” — each of the latter can be either of the former. And a destination device can be any intermediate node in an SRT streaming chain, such as a firewall. You can “call” an SRT source or an SRT destination.