SRT Vs NDI, What Are Their Differences?

The two most common ways to send video from one computer to another are SRT (Secure Reliable Transprt) and NDI (Network Device Interface). Both work over UDP and can be used for live streaming or sending recorded video. They both work well with video conferencing applications, but they do differ in some key areas.


Also, They can be used to send video from one computer to another in real time. They are similar in many ways, but they have some differences that make them suitable for different use cases.


On the other hand, choosing a ptz camera supplier is a top priority before purchasing one. Find out more about the difference between SRT and NDI.

What is SRT?

SRT interface
Source: Unsplash

SRT stands for Secure Reliable Transport. It is an open source protocol that was developed by Haivision and Wowza. SRT retains the core idea and mechanism of UDT, solves complex transmission timing problems, and can greatly reduce delay. At the same time, SRT has strong data recovery capability and forward error correction technology (FEC), which can minimize the packet loss rate and ensure the stability of transmission.

What is NDI?

NDI interface
Source: Unsplash

NDI stands for Network Device Interface. It is a proprietary protocol developed by NewTek that offers some additional features compared to SRT, such as support for audio, multicast and dynamic bandwidth allocation.

What are differences SRT and NDI?

SRT and NDI are both protocols for streaming media over the network. They are similar, but also have some differences that make them each better suited for different scenarios.


Easier and faster deployment: The SRT and NDI protocols are very lightweight, which means they can be deployed in minutes. In comparison, the other popular streaming technologies require special hardware or software that needs to be installed on your computer. This is not only annoying but also takes a lot of time to install and configure everything. With SRT and NDI, you don't need to do any extra work to get started. All you need is a video source (e.g., webcam) and a streaming server (e.g., Wirecast). You can start streaming right away!

More reliable: Since there's no proprietary software involved, it's easy for anyone to access your stream and watch it live. You don't have to worry about whether or not people can see your stream; with SRT and NDI, it's guaranteed! It doesn't matter what type of device people are using; they'll still be able to view your stream as long as they have an internet connection and know where you're streaming from (e.g., Twitch). This makes it much more convenient than other methods that require complicated configurations before users can start watching your content


The main problem with SRT and NDI is that they are not as widely used as HD-SDI or 3G-SDI, so you might be limited to a smaller range of equipment.


In addition, SMPTE 2022 C and D are new standards and there is only a small number of devices that support them. There are also some limitations when it comes to the format of video data. For example, SMPTE 2022 A requires a pixel aspect ratio (PAR) of 1:1 while most HD sources use a PAR of 16:9 or 16:10.


With NDI you can use any source format, but because NDI is a network protocol, latency can be an issue if your network connection isn’t fast enough. The good news is that latency has been reduced significantly over previous versions of NDI, so it’s not usually an issue anymore – especially when you’re streaming over gigabit Ethernet or faster connections.


SRT NDI attributes
Source: Unsplash

The SRT is a single-threaded application. It runs only in one process and cannot be run or debugged in parallel with other applications.

The SRT is a native application. It is written using C++ language and runs on Windows platforms only. You can download a precompiled version of the SRT from this website or build it yourself using Visual Studio 2010 / 2012 / 2013.

NDI has the following attributes:

The NDI is a multi-threaded application. It runs in a separate process and can be debugged in parallel with other applications.

The NDI is an interpreted application (it does not need to be compiled). It is written using Python 2.7 language and runs on Windows, Linux, OS X platforms (except the 32-bit version). You can download precompiled versions of the NDI from this website or build it yourself using Python 2.7 compiler (e.g., ActivePython 2.7).


The most basic workflow in SRT is to capture a video stream from a camera, encode it into H.264, and send it over UDP to a RTSP server. The RTSP server can then pass the stream to a NDI client, which receives the stream and displays it on a screen. Other workflows are possible with SRT, but the basic idea is that SRT enables you to send H.264 encoded video streams over UDP.


NDI’s workflow is similar in that it allows you to send encoded video streams over UDP, but instead of using RTSP as an intermediary protocol, NDI uses RTP/RTCP/SDP directly. This means that you don’t need to install an RTSP server or configure any ports or firewall rules on your machine in order to use NDI. You can simply start sending encoded video streams to any other computer that has an NDI client installed on it – no configuration required!

Bandwidth Used

The bandwidth used by SRT and NDI is typically less than 1Mbps per camera. This is one of the considerations right now by the webcam factory. However, this can vary depending on your network infrastructure and the size of your video files.


SRT uses a variable bitrate ranging from approximately 30kbps to 400kbps depending on the frame rate, resolution, and codec configuration.


NDI uses a variable bitrate ranging from approximately 30kbps to 400kbps depending on the frame rate, resolution, and codec configuration.

Transmission Delay

NDI and SRT both have a delay in the transmission. NDI has a delay of approximately 500 milliseconds and SRT has a delay of approximately 150 milliseconds. The delay is due to the fact that these systems have to transmit the signal through the internet.


NDI is a proprietary protocol developed by NewTek, Inc. It was designed to work with video over IP networks (like those used in multi camera productions).


SRT is a standard developed by the Society of Motion Picture and Television Engineers (SMPTE). It was designed for use with video over traditional SDI cables or fiber optic cables.


SRT is an open source video transport protocol and technology stack that optimizes video streaming performance across unpredictable networks, while NDI is Network Device Interface.

NDI allows people to use real time, ultra low latency video on existing IP video networks, making giving everyone access to high-quality video using the equipment they have today possible. With the help of secure streams and simplified firewall traversal, SRT is able to deliver the best video over the worst networks.​

Applications of SRT include:

With the rapid development of the community, SRT is commonly used in hardware and software-based solutions, which simplifies interoperability for thousands of end-user organizations around the globe.

Broadcast, live streaming, video conference: end-to-end 128/256 bit AES encryption could help protect valuable content. With the attribute of low latency, SRT  protects against jitter, packet loss, and bandwidth fluctuation, delivering high-quality secure video and ensuring the best possible viewing experience under the most demanding network challenges.

Applications of NDI include:

NDI camera for conference
Source: Telycam

Video conferencing: A common application of NDI is video conferencing and live streaming that helps remote users to share their desktop with each other through network connections at any time or place. In addition to this, the standard allows remote users to use different operating systems without having to worry about compatibility issues between different platforms because the protocol does not rely on any specific operating system's protocols but only uses APIs (Application Programming Interfaces) from each platform's SDKs (Software Development Kits).

Which devices/software already support SRT?

SRT is a text-based subtitle format that is supported by many media players.


You can find a list of media players that support SRT here (not updated).


If you want to know if your device supports SRT, you can check the specifications on the manufacturer’s website or Google search for “SRT support” and see if there are any results. If not, contact the manufacturer directly (or maybe they will add support in future firmware updates?). 


Here are some examples of devices that support SRT:

Apple TV 4K and 4th Gen Apple TV

Amazon Fire TV Cube (but not Fire TV Stick)

Apple iPad (all models), iPhone & iPod touch (all models) iOS 6+

Android phone/tablet (Android 4+)

Linux desktop (VLC, MPlayer2, PotPlayer, MPC-HC)

Which one is better for video transmission?

NDI equipment ptz camera
Source: Telycam

For most applications, SRT is a better choice than NDI. This is because SRT offers higher quality and more control over the video signal than NDI.


SRT vs NDI – Which One Is Better for Video Transmission?


In the world of live video transmission, there are two major standards that have been developed to replace traditional analog methods: SMPTE 2022-6 (SMPTE 2022) and 3G-SDI. The former is a shared standard that allows for long distance transmission of uncompressed H.264 video signals with embedded audio, while the latter is used for short distance transmission of uncompressed H.264 video signals with embedded audio.


Both SRT and NDI can be used to transmit HDCP protected content over IP networks at distances up to 100m/328ft without requiring any additional hardware or software licenses beyond what you already use for your existing SDI equipment.


These protocols also allow you to transmit video in formats other than HD, including 4K/UltraHD and even 8K! Furthermore, both protocols support multiple simultaneous streams of uncompressed HD video at full frame rate (or higher) with sub-second latency across networks as wide as 100Mbps.

Choose Reliable PTZ Camera Manufacturer For SRT And NDI Productions

Telycam-Best Choice

telycam logo
Source: Telycam

Company Overview:

Brand Name: Telycam

Year Founded: 2014

Headquarters: Shenzhen, China


Telycam (Telecam Technology Co.,Ltd) is a specialized manufacturer of PTZ Cameras for video conferencing and live streaming. Telycam ( webcam & ptz camera company Telycam) , which has been involved in the audiovisual business since 2014, combines the benefits of a solid supply chain, well-organized production, significant R&D capabilities, and expert services in order to provide the finest audiovisual solutions to our consumers. They have established their name  because of their Telycam webcam & PTZ.


Telycam has grown at a quick pace since its inception in 2014. Throughout the years, we have insisted on innovation and have achieved little successes.


Key Products:

Video Conference Cameras

Live Streaming PTZ Cameras

PTZ Controllers


Other questions

What is the difference between NDI and SDI?

NDI is an open standard developed by Rovi, which allows any device to communicate with any other. The protocol enables the transfer of live video ( ndi ptz camera) and audio over Ethernet or IP networks without requiring proprietary hardware or special networking equipment.

SDI (Serial Digital Interface) was originally developed by Sony and Ampex in 1983 as a way to transfer digital audio over existing analog lines so that they could be connected to digital recording devices like DAT recorders. It uses a serial interface running at 48 kHz with 8-bit resolution at 2 channels of 20-bit audio per second each channel (32-bit sample size).

What is the difference between SRT and RTMP?

SRT is a video format ( ptz cameras for live streaming) that works with Flash Player. It is typically used for streaming live events such as sporting events, concerts and political debates.

The main difference of RTMP is that it allows videos to be streamed over the Internet, whereas SRT files can only be played back locally on your computer.

SRT is a video format ( ptz cameras for live streaming) that works with Flash Player. It is typically used for streaming live events such as sporting events, concerts and political debates.


In the end, no one is going to tell you whether your project is better with one or the other. There are reasons people find SRT preferable and reasons they choose NDI over SRT. 


The best way to know how much either is necessary for your project design is by understanding what each technology offers, their weaknesses, and quirks for both. 


Then you can decide for yourself which technology better suits your needs


Selecting a trustworthy PTZ manufacturer, like Telycam, is critical. If you want a normal ptz camera, grab a quote now!

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