Articles on: Receiving

Receiving SRT in Astra

The Secure Reliable Transport (SRT) protocol is a data transfer protocol designed to enable secure and reliable delivery of high-quality video over unpredictable networks. The Astra interface supports SRT as an input protocol, allowing users to receive SRT streams from remote sources

Available for Astra versions released after 2021-12-21

SRT protocol

The Secure Reliable Transport (SRT) protocol is an open-source video streaming protocol designed to provide low-latency, high-quality video streaming over unreliable networks. SRT uses end-to-end encryption and provides a range of features designed to enhance reliability and security, including error correction, congestion control, and retransmission of lost packets. SRT is often used for live video streaming applications, such as sports and news broadcasts, where maintaining a reliable, high-quality connection is critical

Address format

SRT address is used to identify the location of the media stream that is being transmitted over the network


SRT Options:

streamid=ID – stream identifier
passphrase=PASS – password for the encrypted transmission. Password length should be in range 10 .. 79 characters
pbkeylen=N – crypto key length in bytes. Possible values: 16, 24, 32
tsbpdmode – timestamp-based packet delivery mode
packetfilter - injecting extra processing instructions at the beginning and/or end of a transmission to implement Forward Error Correction (FEC)
interface – name of the local interface. If interface is not defined Astra accept requests from any interface
port – local port

Additional Options:

tsbpdmode – timestamp-based packet delivery mode

Web Interface

One of the biggest challenges of working with the Secure Reliable Transport (SRT) protocol is navigating the range of technical requirements and settings involved in the setup process. Fortunately, Astra streamlines this process by offering a comprehensive set of SRT input configuration options

To add a new SRT input in Astra, users can navigate to the "New Stream" tab or the settings of an existing stream and select the "Input Type" option as either SRT

Input type - this parameter is the first option on the SRT settings tab and is used to select the input type. To configure SRT reception, select "SRT" from the drop-down list. This enables the SRT-specific configuration options and allows you to enter the necessary information to receive an SRT stream
SRT mode - this parameter determines whether Astra will act as the caller or listener when establishing an SRT connection. To receive an SRT stream, select "Listener" from the drop-down list. This tells Astra to wait for incoming connections from the SRT stream's sender
Local interface - this parameter specifies the network interface that Astra will use to receive the SRT stream. The default value is "Any interface", which means that Astra will listen for incoming SRT connections according to system routing rules. If you want to restrict Astra to a specific interface, select it from the drop-down list
Port - this optional parameter specifies the network port that Astra will use to receive the SRT stream
Timeout - this optional parameter specifies the amount of time (in milliseconds) that Astra will wait for incoming data from the SRT stream before timing out. The default value is 5000 milliseconds (5 second), but you can increase or decrease this value if necessary
Latency - this optional parameter introduces a specified amount of delay (in milliseconds) into the SRT stream. The default value is 120ms. Increasing the latency can improve stability but increases delay, and decreasing it can reduce delay but may make the connection less stable
Passphrase - this optional parameter sets a passphrase for secure communication over the SRT stream. The default value is empty. If a passphrase is set, both sender and receiver must use the same one to establish a connection
Crypto key length - this parameter sets the length of the cryptographic key used to secure the SRT stream. The default value is 128 bits, which is enough for SRT reception to work. However, you can increase or decrease the key length if needed for stronger or weaker security
Timestamp - based packet delivery mode - this parameter enables or disables the timestamp-based packet delivery mode of SRT. When enabled (checked), SRT uses timestamps to ensure that packets are delivered in the correct order, even if they arrive out of order. This can improve the quality of the stream but may increase latency. The default state of this parameter is disabled

Updated on: 10/05/2023

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