News & Trends

We all rely on streaming technology daily for education, entertainment, and business. For most of us, video is the first thing we think of when we think of streaming, but the term also refers to data and audio. Streaming is the transfer of information in real time. Staying in touch. Keeping up to date. It’s an integral part of our day-to-day routine.

Since we’re so familiar with using streaming technology, it can be easy to overlook the importance of protocols in video streaming. All transport protocols available to content creators, broadcasters, and remote teams are not created equal and may have different purposes. The right protocol can mean the difference between an awkward, delayed video conference call and a seamless connection that brings a team together. Let’s compare the NDI protocol with SRT, for instance.

NDI might be a good option when live streaming a crowded event to an overflow room but once you need to bring in a source from outside your network, you may need an additional protocol to keep things running smoothly. This is because NDI is designed for use within a local area network, a network of computers that are connected with a router.

When the situation calls for connecting to those outside of the router, SRT is the preferred protocol. It’s designed to transport video over networks, including the public internet, making it ideal for those who want to transfer video over long distances. Choosing to use SRT is the ideal option for sending smooth, reliable video across town, the country, or beyond.

Understanding SRT Protocol

SRT is an open-source transport protocol that delivers audio and video across networks with minimal lag and maximum reliability. The qualities of the protocol are included in the name, SRT is an acronym that stands for Secure Reliable Transport. SRT monitors transmissions with a two-way back channel that catches issues such as packet loss and corrects errors in real-time, minimizing video jitter and lag.

Developed by Haivision, the SRT protocol was created in pursuit of cutting the cost of video contribution by satellite and private networks. Once released as an open-source technology stack and protocol, support for SRT grew quickly and its use became widespread in major streaming platforms, clouds, and broadcast providers. SRT protocol has the support of the SRT alliance, an open-source community that fosters widespread adoption and innovation. Today, the SRT alliance has over 600 members including Google Cloud, Paramount, Sony, and YouTube. 

Key Features of SRT Protocol

In today’s world, everyone is looking for two things: reliability and security. The key SRT features take these needs seriously. As the saying goes, safety first. SRT utilizes symmetric encryption algorithms for end-to-end security. The protocol has also simplified firewall transversal, allowing you to stream without asking your network admin for allowances.

The key to SRT’s reliability lies in the latency buffer on both the sender and receiver side. The SRT receiver reconstructs the streaming packets before they get sent to a decoder. If a packet has been dropped on the way, the receiver will send a negative acknowledgement (NAK) to the sender which will resend the missing packet. In reducing packet loss, this process reduces latency and network jitter.

SRT was designed to be open source from the very beginning, making it easy and cost-effective to adopt. When implementing SRT, there’s no need to worry about royalties, long-term contracts, or subscription fees. Because of this, the widespread adoption of the protocol has led to greater interoperability. SRT can be deployed throughout video and audio workflows and users can rest assured that multi-vendor products will work smoothly together. Users don’t have to stress about video and audio formatting either. Because of the way the SRT protocol transports your content, it is inherently payload agnostic.

Benefits of Using SRT Protocol

Low Latency

SRT protocol ensures smooth and steady streaming by checking and correcting errors that may result in jitter and bandwidth fluctuation in real time. The streaming quality is noticeable, even on unreliable networks. SRT offers faster media delivery than TCP/IP while remaining less susceptible to data loss and corruption than UDP transmission

Versatility

The stream error correction can be set up to accommodate whatever deployment conditions might be in play. SRT is also versatile when it comes to content. Acting as a wrapper, the transport can reliably carry a range of video formats, codecs, resolutions, or framerates.

Security

By utilizing the same 128/256-bit AES encryption that governments throughout the world have in place to protect their data, SRT ensures unauthorized parties can’t eavesdrop on streaming content. And because SRT limits the need to open exterior firewall ports with their handshaking process, it contributes to network safety and simplifies the workload for IT departments.

SRT Protocol in Remote Production

Remote production is any multi-camera production that takes place away from a studio setting such as live sports or concert broadcasting. When taking the production out of the studio, many challenges can occur. When you can’t rely on satellite or fiber to broadcast your data, streaming issues such as lag and jitter can interrupt the quality of your content.

As long as the SRT encoder is at the source and the receiver, the SRT protocol enables remote highly secure streaming across a range of networks including public internet. This protocol can be used for more reliable live broadcasting and cloud collaboration.

Comparing SRT Protocol with NDI Protocol

Much like SRT, NDI (Network Device Interface) enables remote production for a wide range of creators by offering high-quality data transport. However, NDI is a different tool, used for a different purpose.

Here are some distinctions between SRT and NDI protocols: 

Use cases

SRT and NDI are uniquely tailored for specific video transmission needs, each excelling in their respective domains. SRT shines in the realm of low-latency video transmission over unreliable networks, such as the public internet. It's built to thrive in long-distance and unpredictable conditions, ensuring that your video reaches its destination with minimal delay. This makes SRT an ideal choice for scenarios where network stability cannot be guaranteed.

On the other hand, NDI is crafted for local area network (LAN) environments, optimized for delivering low-latency, high-quality video in real-time production settings. Its prowess is often leveraged in live video production setups like studios, where seamless and rapid video transmission is crucial. Together, SRT and NDI provide versatile solutions for a range of video transmission challenges, ensuring you have the right tool for the task at hand.

Video quality

SRT and NDI both support high-quality video transmission, but they excel in different environments. SRT is designed to handle network challenges, compensating for jitter and packet loss to maintain video integrity even when conditions aren't ideal. NDI works within LANs, allowing it to transmit uncompressed or lightly compressed video with minimal quality loss, making it highly effective in local network environments.

Integration

SRT and NDI offer robust integration capabilities, though both protocols meet different video needs. SRT is a favorite in the broadcast industry, as it integrates seamlessly with many broadcast encoders, decoders, and streaming platforms. Its versatility is also amplified by the support from the SRT Alliance. This makes SRT a go-to choice for broadcasters seeking reliability and extensive compatibility.

NDI is the right protocol for video production workflows, due to how seamlessly it integrates with software and hardware from industry leaders like Ross Video and OBS. Its strong integration capabilities makes it an integral tool for production environments, enabling smooth operations and high-quality video transmission. 

Security

SRT is equipped with built-in encryption using AES 128/256, ensuring that video streams over the internet remain secure. This level of encryption makes SRT particularly well-suited for broadcast and public streaming where data protection of high importance. SRT ensures that content remains confidential and protected during transmission with its more robust security features.

NDI, on the other hand, doesn’t natively encrypt its stream. Since it is primarily utilized in controlled, closed environments such as studios or production networks, encryption mechanisms are not incorporated within the protocol. These secure and managed spaces have their own network security protocols to account for this shortcoming. NDI is focused on delivering high-quality video transmission efficiently within these protected contexts.

The Takeaway

There’s an old saying: A stitch in time saves nine. Well, what if that stitch took a mere millisecond, less than a twitch of the eye, then that’s exactly what SRT does. The two-way back channel catches errors and corrects them before they cause problems, greatly reducing troublesome latency. It can be used far afield from home offices and corporate studios, capturing the action where it happens, in the real world.

As an open-source protocol, SRT access is growing stronger every moment, becoming more available to everyday people who may have never thought about their streaming protocols before. It’s a protocol that, when added to your toolbox, can expand your reach and improve your content.

SRT is growing more popular in an AV world that moves fast. Keep up with the times when you sign up for AVIXA’s Broadcast AV Power Hour: Remote Video Control Techniques and Tools. This webinar can teach you about video protocols in remote production, production platforms, and vital networking practices.