Four Free SRT Encoders for Windows: A Guide for the "SDI/NDI → SRT" Task
In recent years, the SRT protocol has rightfully earned its place in the sun: it is used for delivering live video over the internet where latency and resilience to packet loss are critical. In this article, we look at the practical task of capturing a signal from an SDI card or an NDI stream and transmitting that stream via SRT to a remote server. We will examine solutions to this task for the Windows platform.
We'll compare four free encoders. Three of them are open-source projects (FFmpeg, GStreamer, OBS Studio). The fourth is SRT Streamer Lite: it is free software but proprietary (closed source, from a specific vendor).
We'll focus on several aspects:
ease of use — how quickly a person without a deep technical background can get a working SDI → SRT setup;
SDI card support — we'll look at support for SDI cards from various manufacturers (BlackMagic, AJA, Magewell, etc.);
multi-channel audio — the ability to transmit multiple audio channels, not just stereo;
NDI support — the ability to capture an NDI source is as important as SDI;
recovery after connection loss — what happens when the connection is lost.
All these tools use the canonical SRT library, so there is no difference between them in terms of SRT functionality. Additionally, all the tools under consideration support hardware encoding.
Ease of use: considering the advancements in AI, it can be said to be quite simple. ChatGPT or DeepSeek can easily write the command you need. SDI card support: maximum support for DeckLink cards. For cards from other manufacturers, you'll need to search for and try different builds from the hardware manufacturers. Multi-channel audio: full control, but it requires an understanding of what you want to achieve. NDI support: not available by default. Requires a special build. Recovery after connection loss: there is NO automatic restart in the event of connection loss or temporary loss of the source signal. The issue is resolved with external scripts.
GStreamer
What it is: A pipeline framework (a chain of elements), typically used via gst-launch-1.0 or a custom application.
Ease of use: Low; the syntax of pipelines and debugging "which element failed to negotiate caps" requires time.
SDI card support: Maximum support for DeckLink cards. For cards from other manufacturers, you'll need to find plugins from the hardware manufacturers.
Multi-channel audio: Extremely flexible: splitting tracks, mixing, separate branches for encoding — if the pipeline is built consciously.
NDI support: Supported via a special plugin. Due to the plugin architecture, unlike FFmpeg, adding the protocol requires installing only this plugin.
Recovery after connection loss: In the event of an SRT connection break, it will try to reconnect by default without stopping the command.
OBS Studio
What it is: A live streaming program with scenes, mixer, and overlays.
Example configuration:
According to the article's criteria:
Ease of use: The interface might seem somewhat confusing for a beginner, considering that OBS is a powerful tool for a wide range of tasks. While AI can assist by writing commands for FFmpeg and GStreamer, with OBS's interface, you'll need to click around yourself.
SDI card support: Maximum support for DeckLink cards. For cards from other manufacturers, it works via DirectShow filters, but there may be nuances.
Multi-channel audio: Capable of sending 6 audio pairs.
NDI support: so-so.
Recovery after connection loss: Automatically handles reconnections by default.
SRT Streamer Lite
What it is: A free utility for Windows designed with a "quickly set up and start" approach.
Where it's suitable: When you need a simple graphical interface on Windows: select SDI (or HDMI, NDI, etc., as needed), set the address, mode, bitrate, codec — and go. It is suitable for those who don't want to assemble long command-line strings.
As an additional feature, it includes a player for receiving studio return feedback, which can be output via SDI/HDMI, with the ability to select audio channels. This is convenient if you need to set up a bidirectional communication link.
According to the article's criteria:
Ease of use: The interface is designed for a single purpose and leaves no room for "getting lost."