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SRT streaming - best quality video over the worst networks

Dec 20, 2022

The ultimate goal of SRT broadcasting is to deliver video with the lowest possible latency over unpredictable public networks without any loss in quality.

In this post, we'll explore how SRT protocol works, why it's open source, and who uses it.

What is SRT streaming

SRT is a data transmission technology developed and implemented by Haivision. Considered safe and secure.

Regardless of the conditions, this protocol ensures stable signal transmission. The source code is open and therefore constantly improved. 

With SRT, you can stream safely without a firewall.

How it works

The protocol transmits data over the network between two points and quickly adapts to what is happening in it. 

For the SRT protocol to work correctly, the main thing is to set the buffer size and the latency correctly. Retransmission with minimal latency makes it possible to recover lost packets.

Can SRT replace satellites?

To answer this question, let's take a closer look at what opportunities this technology provides:

  • Connection is so secure that no outsider is able to listen in. Security and reliability are ensured through end-to-end transmission with 128/256-bit AES encryption.

  • SRT protocol has bypassed TCP/IP in terms of delay. It transmits even high-performance video with high quality, and it also knows how to check for errors.

  • SRT is content-agnostic and can transmit any video format with any characteristics to any device.

  • Video is transmitted without packet loss, artifacts, jitter, etc.

  • Using SRT via public networks is cheaper than satellite or user network infrastructure.

  • Unique bi-directional User Datagram Protocol (UDP) stream, continuously sends and receives control data during streaming.

Who needs SRT protocol

You may be using this technology without knowing it. The most common thing this protocol does is send MPEG streams over the open Internet.

Thousands of organizations around the world are using this protocol right now.

SRT is used for transmission from IP cameras, video encoders and decoders, gateways, OTT platforms and CDNs.

Notable technology partners are Avid, AWS and Microsoft, among others.

End users: NFL, Comcast, Al Jazeera, Fox News, Sky News and NASA.

NASA uses SRT technology to transmit video from space.

In 2020, SRT helped deliver over 600 broadcasts to show the virtual NFL Draft live.

Streaming has become an indispensable tool across all major industries - from business to government to education to defense.

Mark Cymontkowski, SRT Architect, explains how you can also use SRT:

  • to connect to the Internet of things (IoT)

  • to exchange metadata

  • as a communication protocol

  • to deliver uncompressed data

Last year, the developers of SRT, Haivision made a report on how the field of IP broadcasting has changed and what transmission protocols are used. In 53% of cases it was SRT broadcast.

SRT streaming community

The pioneers of this technology, Haivision, founded the SRT Alliance about 6 years ago. This was done so that the technology would remain accessible and continuously improved through open source.

To date, the alliance consists of hundreds of technology providers (more than 500) who are constantly working to improve it. Callaba Cloud is also a member of SRT Alliance.

Community members regularly update the roadmap and Interop Plugfests for compatibility with other technologies.

If you need to dive deeper into the topic, visit the online meeting “SRT Tuesday webinars”. You would be able to see how SRT broadcasting is used and implemented by major technology providers. You can follow the release notes on GitHub.


The Real Time Messaging Protocol (RTMP) is still very popular, but from the technical standpoint it is not as advanced as SRT.

The main function of RTMP is to transfer content from the encoder to the online video host.

Since this protocol is famous for its low latency and rare buffering, broadcasters have used it for live broadcasts.

But RTMP cannot transfer HEVC video content, so it's not ideal for new applications.

*HEVC (High Efficiency Video Coding), also known as H.265,  is a video compression codec that uses more efficient algorithms than H.264.

SRT is considered more modern.

22 years ago, RTMP appeared as a way to transfer video and audio information from servers to the Macromedia Flash player. In 2010, Adobe bought Macromedia, who owned the development of RTMP along with the technology, and upgraded it to broad streaming.

But here’s why SRT is technologically superior :

SRT features a unique bi-directional UDP stream that works non-stop with data while on the air. Network conditions may change, but you won't lose data and the quality won't change; SRT is capable of adapting to changes.

However, SRT and RTMP are not actually mutually exclusive, they complement each other.

For example, you can use SRT to bring remote guest feeds to your  production encoder, but stream your program over RTMP, because that's what your preferred CDN supports.

If we talk about easy access to this technology, then you can enjoy all the advantages of flexible broadcasting with Callaba Cloud.

Callaba Cloud supports SRT, MPEG-2/.TS, RTSP, RTMP, HTTP, UDP, HLS/m3u8, MPEG-DASH/mpd streaming in your region or worldwide.

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