June 3, 2019

SRT sender max bandwidth

SRT is a streaming protocol which adapts to the network conditions, helps compensate for jitter, bandwidth fluctuations and has error recovery mechanism to minimize the packet loss.

These excellent features lead to the lost packets re-transmission, which increases the bandwidth between sender and receiver. This is why if the network conditions are bad enough, the re-sent packets may consume all available throughput.

As you cannot control the network environment completely, you should set up the maximum bandwidth available for transmission over SRT for every SRT sender. Even if your network is fine now, it's a good practice to prevent any fluctuations in the future.

This maximum bandwidth limitation is set up using "maxbw" parameter for SRT streaming.
It needs to be set on sender side.

We recommend having maxbw value twice as much as your stream bandwidth, e.g. if you send 1Mbps, your maxbw should be 2Mbps.

We also strongly encourage you to set both "maxbw" and "latency" parameters for streaming via SRT. Please read this article to learn more about this parameter.

Proper configuration option is also available for SRT setup in Nimble Streamer. First, please refer to SRT setup article to get familiar with the general setup process. Once you complete all required steps, use custom parameter fields to define appropriate entry as shown on the figure below.

Please notice that maxbw is defined in bytes per second, NOT bits per second. So if you'd like to set maximum bandwidth to 1 Mbps, you'll have to specify 125000 as your designated value. This is an SRT-specific approach to value definition.

If you have any questions regarding SRT setup and usage, please feel free to contact our helpdesk so we could advise.

Related documentation

Nimble Streamer SRT feature setHaivision blog: Reliable Low Latency Delivery with SRT+SLDP