UDP (User Datagram Protocol) is an essential transport layer protocol in networking, known for its simplicity and speed. It plays a significant role in broadcasting and streaming applications, including digital TV delivery, where data packet loss can be tolerated but speed and delays are crucial.
One of the key applications of UDP is in the delivery of TV content over multicast networks. This approach is commonly used across a range of sectors, with some of the most prevalent use cases as follows:
Media Address configure the destination of the UDP stream. The format for this address is as follows:
In square bracket optional parameters.
interface - local interface name, such as
eth0. If this field is not defined, the UDP stream will be delivered according to the system routes
address - IPv4 address of the multicast group, localhost, or remote host for unicast delivery
port - network port for UDP delivery. If not specified, the default port
1234 is used
Additional options can be defined after the
# symbol and are separated by the
& symbol, similar to the parameters in a typical URL. Here are the available options:
socket_size=bytes - defines custom size of the system socket. If not specified, the default value is taken from the system configuration:
sync - enables the transmission of UDP in a separate thread with bitrate syncing
no_sync - disable bitrate syncing if it has been enabled globally
cbr=Kbps - enables bitrate syncing and turns on the insertion of stuffing packets to achieve a constant bitrate
ttl=n - controls the lifetime of the datagram to prevent it from looping indefinitely due to routing errors. The default value is
sap - turn on SAP. Read more on Session Announcement Protocol for Multicast
Here are some examples of how the media address format can be used in different scenarios with Astra:
188.8.131.52 via a specific network interface like
eth0, the address would look like this:
184.108.40.206 and you want the system to determine the route (interface), the address would be:
192.168.1.100, the address would look like this:
220.127.116.11 on a specific port, say
5000, the address would be:
24000Kbit/s, the address would be:
To configure a new UDP output using the Web Interface, begin by selecting "New Stream" from the main menu. Then, in the Output List, click on the gear icon and set the "Output Type" to UDP. Alternatively, you can modify an existing stream by opening its settings, adding a New Output, and clicking on the corresponding gear icon.
Most options presented in the web interface correspond directly to the components of the UDP address, as described in the "Media Address Format" section.