SRT Encoder: What It Is, How It Works, and How to Choose One

SRT is quickly replacing RTMP as the go-to contribution protocol for professional live streaming. Tests show that SRT can deliver video with 2 to 12 times lower latency than RTMP, depending on whether you use software or dedicated hardware. For developers and broadcast engineers building live video workflows, an SRT encoder is now a core piece of the streaming pipeline.

But what exactly is an SRT encoder, and how does it differ from the RTMP encoders most teams already use? This guide covers everything you need to know: how SRT encoding works under the hood, the types of encoders available, top hardware and software options, configuration best practices, and how to get started with SRT-based ingest in your own application.

What Is an SRT Encoder?

An SRT encoder is a hardware device or software application that compresses raw video into a streamable format and transmits it using the Secure Reliable Transport (SRT) protocol. SRT is an open-source video transport protocol built on top of UDP that improves live video delivery across unpredictable networks like the public internet.

Where a traditional RTMP encoder sends video over TCP, an SRT encoder uses UDP combined with an intelligent error-correction mechanism called ARQ (Automatic Repeat reQuest). This means the encoder detects lost packets in real time and retransmits only the missing data, rather than waiting for the entire TCP stream to catch up.

The result is lower latency, better resilience on unstable connections, and built-in AES encryption that RTMP does not offer natively.

An SRT encoder handles two main jobs:

1. Encoding — Compressing raw video from a camera, capture card, or screen into a codec like H.264 or HEVC.
2. Transport — Wrapping that compressed video in the SRT protocol and sending it to a destination server, decoder, or cloud platform.

Because SRT is codec-agnostic, an SRT encoder can pair the protocol with H.264, HEVC, or even AV1 depending on the encoder’s capabilities.

SRT Encoder vs RTMP Encoder

If your team currently uses RTMP for live ingest, you might wonder why switching to SRT matters. Here is a direct comparison of the two encoder types:

SRT is the stronger choice for contribution feeds where latency and reliability matter, such as remote production, sports broadcasting, and event streaming. RTMP still has wider platform compatibility for distribution to social media endpoints, but many platforms now accept both. LiveAPI supports both RTMP and SRT ingest, so you can choose whichever protocol fits your workflow.

How Does an SRT Encoder Work?

Understanding the SRT encoding pipeline helps you configure it correctly. Here is the step-by-step process from camera to viewer:

1. Video capture. The encoder receives raw video from an input source — an HDMI or SDI camera feed, a screen capture, or a file. Hardware encoders have physical inputs. Software encoders capture from connected devices or virtual sources.

2. Compression. The encoder compresses the raw video using a codec (usually H.264 or HEVC). This reduces the data from gigabits per second of raw video down to a manageable bitrate, typically 2-20 Mbps depending on resolution and quality settings.

3. SRT packetization. The compressed video is wrapped into SRT packets and sent over UDP. Each packet gets a sequence number and timestamp so the receiver can detect gaps.

4. ARQ error correction. If the receiver detects a missing packet, it sends a NAK (negative acknowledgment) back to the encoder. The encoder then retransmits only the missing packet. This is faster than TCP’s approach of halting the entire stream until lost data is recovered.

5. Latency buffer. SRT uses a configurable latency buffer (default 120 ms) that gives the protocol time to request and receive retransmissions before the packet’s playback deadline. Setting this correctly is critical for stream quality.

6. AES encryption. If configured, SRT encrypts the entire payload using AES-128 or AES-256. Both the encoder and decoder must share the same passphrase and key length.

7. Connection modes. SRT supports three connection modes:

• Caller — The encoder initiates the connection to a listener (most common for pushing to a server).
• Listener — The encoder waits for an incoming connection (useful when a server pulls from the encoder).
• Rendezvous — Both sides initiate at the same time, and the first to complete the handshake becomes the caller.

8. Delivery. The SRT stream arrives at the destination — a decoder, a media server, or a cloud video streaming platform — where it is decoded and either played back or transcoded into HLS for distribution to viewers.

Types of SRT Encoders

SRT encoders fall into two categories: hardware and software. Each has distinct strengths depending on your use case.

Hardware SRT Encoders

A hardware SRT encoder is a dedicated physical device with built-in video inputs (HDMI, SDI), an encoding chip, and SRT transport capability. You plug in a camera, configure the destination, and the device handles everything.

Best for: Remote production, fixed installations, field contribution, mission-critical broadcasts where reliability is non-negotiable.

Key characteristics:

• Dedicated encoding hardware (ASIC or FPGA) that does not compete with other software for CPU
• Physical inputs for professional cameras (SDI, HDMI)
• Always-on reliability with no operating system crashes or software conflicts
• Compact, portable form factors for field use
• Higher upfront cost ($500-$5,000+ depending on features)

Software SRT Encoders

A software SRT encoder is an application running on a general-purpose computer (Windows, macOS, or Linux) that uses the machine’s CPU or GPU for encoding and sends the output via SRT.

Best for: Budget-conscious setups, creative productions with overlays and scene switching, development and testing, streams that need frequent reconfiguration.

Key characteristics:

• Runs on existing hardware (laptops, desktops, servers)
• Flexible scene composition with overlays, transitions, and multiple sources
• Lower cost (many options are free or under $100)
• Depends on host machine performance and stability
• Easier to update and reconfigure

Hardware vs Software SRT Encoder Comparison

Top SRT Encoders for Live Streaming

Here are the leading SRT encoder options across both hardware and software categories.

Hardware Options

Haivision Makito X4 — A broadcast-grade video encoder used by major broadcasters and sports networks. Supports up to four simultaneous 4K HEVC SRT streams with sub-second latency. Designed for rack-mount deployment in production environments. Price: Enterprise pricing (contact Haivision).

Epiphan Pearl Nano — A compact, single-channel SRT encoder built for remote contribution. Supports 4K HDMI input, SRT caller and listener modes, and can be pre-configured for ship-to-site deployments. Cloud-manageable via Epiphan Edge. Price: Around $1,500.

Teradek Vidiu X — A portable encoder that supports SRT, RTMP, and RTMPS. Handles 1080p60 H.264 encoding with bonded cellular connectivity for field use. Good for mobile journalists and event streamers. Price: Around $1,000.

Magewell Ultra Encode — A versatile encoder supporting SRT, RTMP, RTSP, and NDI output. Available in HDMI and SDI models with 4K input support. Compact desktop form factor. Price: Around $1,000-$1,500.

LiveU Solo — A field encoder with SRT support and cellular bonding for streaming from locations without reliable internet. Supports up to 4K HEVC. Popular for news gathering and remote event coverage. Price: Around $1,000.

Software Options

OBS Studio — The most popular free, open-source encoder. Supports SRT output natively with caller, listener, and rendezvous modes. Handles H.264 and HEVC encoding via x264, NVENC, or QuickSync. Available on Windows, macOS, and Linux.

vMix — A professional production suite for Windows that supports SRT output with up to four simultaneous SRT destinations. Includes mixing, overlays, instant replay, and NDI support. Price: $60-$1,200 depending on license tier.

Wirecast — A professional streaming and production tool from Telestream. Supports SRT output alongside RTMP. Offers multi-camera switching, graphics, and ISO recording. Price: Starting at $599.

FFmpeg — A command-line tool that supports SRT encoding and decoding. Useful for developers building automated encoding pipelines or serverless workflows. Free and open source.

Larix Broadcaster — A mobile SRT encoder app for iOS and Android. Supports SRT, RTMP, and RIST protocols from a smartphone. Good for mobile contribution feeds. Free with optional paid features.

Advantages of SRT Encoders

Lower Latency Than RTMP

SRT encoders typically achieve 300-500 ms end-to-end latency, compared to 1-3 seconds with RTMP. For remote production, sports, and interactive streaming, this difference is significant. The protocol’s UDP foundation and selective retransmission avoid the head-of-line blocking that slows TCP-based protocols.

Built-In AES Encryption

Every SRT encoder can encrypt the stream using AES-128 or AES-256 without any additional infrastructure. RTMP has no native encryption — you need RTMPS (RTMP over TLS) for secure transport, and not all endpoints support it. SRT encryption is configured with a shared passphrase between encoder and decoder.

Network Resilience and Error Correction

SRT’s ARQ mechanism retransmits only the specific packets that were lost, rather than halting the entire stream. Combined with a configurable latency buffer, SRT encoders maintain stream quality over networks with packet loss, jitter, and fluctuating bandwidth — like cellular connections, satellite links, or congested public internet paths.

Firewall and NAT Traversal

SRT’s caller/listener model makes it easier to traverse firewalls and NAT devices compared to RTMP. The caller mode initiates an outbound connection (which most firewalls allow), while listener mode opens a specific port. Rendezvous mode lets both sides initiate, which can work even when both are behind NAT.

Codec Flexibility

Unlike RTMP, which is effectively limited to H.264, SRT is codec-agnostic. An SRT encoder can transmit H.264, HEVC, AV1, or any other video codec. This future-proofs your encoding pipeline as newer codecs gain adoption.

Open Source and Royalty-Free

The SRT protocol is open source under the MPL-2.0 license, maintained by the SRT Alliance with over 500 member organizations. There are no licensing fees to use SRT in your products or workflows, unlike some proprietary transport solutions.

Disadvantages of SRT Encoders

Limited Platform Support for Distribution

While SRT adoption is growing fast, many consumer-facing platforms (YouTube Live, Facebook Live, Twitch) still primarily accept RTMP for ingest. You may need an intermediary server or service to convert SRT to RTMP or HLS for final distribution. Services like LiveAPI handle this conversion automatically — you can ingest via SRT and distribute via HLS to any device.

Requires Matching Decoder

Both ends of an SRT connection must speak the protocol. If your destination server does not support SRT ingest, you cannot use an SRT encoder without adding a decoder or gateway in between. RTMP, by comparison, is accepted almost everywhere.

Configuration Complexity

SRT has more tunable parameters than RTMP — latency buffer, bandwidth overhead, encryption settings, and connection modes. Misconfiguring these (especially the latency value) can cause stream breaks or excessive delay. RTMP is simpler: point at a URL with a stream key and go.

Higher Hardware Cost

Dedicated hardware SRT encoders cost $500-$5,000+, while basic RTMP hardware encoders can start under $200. Software SRT encoders (like OBS) are free, but if your use case demands hardware reliability, the price difference matters.

Learning Curve for Caller/Listener Modes

SRT’s caller, listener, and rendezvous modes add flexibility but also complexity. Teams used to RTMP’s simple push model need to understand which mode to use, which side opens the port, and how to handle NAT traversal. This is straightforward once learned, but it is an additional concept to master.

With a clear picture of what SRT encoders offer and where they fall short, the next step is getting one running in your own streaming workflow.

How to Set Up an SRT Encoder

Here is a step-by-step guide to configuring an SRT encoder, using OBS Studio as the software example and a cloud streaming API as the destination.

Step 1: Choose Your Encoder

Pick a hardware or software SRT encoder based on your requirements. For testing and development, start with OBS Studio (free). For production field work, consider a hardware encoder like the Epiphan Pearl Nano or Haivision Makito X4.

Step 2: Configure Video Settings

Set your encoding parameters based on your content and available bandwidth:

• Resolution: 1080p (1920×1080) for most use cases, 4K (3840×2160) if your encoder and network support it
• Frame rate: 30 fps for standard content, 60 fps for sports or gaming
• Codec: H.264 for maximum compatibility, HEVC for better quality at lower bitrates
• Bitrate: 4-8 Mbps for 1080p H.264, 2-6 Mbps for 1080p HEVC

Step 3: Set Up SRT Output in OBS

In OBS Studio:

1. Go to Settings > Stream
2. Set Service to “Custom”
3. Enter the SRT URL in the Server field:

srt://your-server-ip:port?mode=caller&latency=200000&passphrase=yourkey

1. Leave the Stream Key field empty (SRT does not use stream keys)
2. Click Apply

Key SRT URL parameters:

• mode=caller — OBS initiates the connection (default)
• latency=200000 — Latency buffer in microseconds (200 ms in this example)
• passphrase=yourkey — AES encryption passphrase (minimum 10 characters)
• pbkeylen=32 — Key length in bytes (16 for AES-128, 32 for AES-256)

Step 4: Set the Latency Buffer

The latency value is the most important SRT configuration parameter. Set it too low and you will get stream breaks. Set it too high and you add unnecessary delay.

Rule of thumb: Set latency to at least 2.5x the round-trip time (RTT) between your encoder and the destination server. For most internet connections, 120-300 ms works well. For cellular or satellite links, use 500-1,000 ms.

Step 5: Enable Encryption

Set a passphrase on both the encoder and decoder sides. The passphrase must match exactly. Use AES-256 for maximum security. If either side has a mismatched passphrase or key length, the connection will fail silently.

Step 6: Test the Connection

Start the stream and verify the connection:

• In OBS, check the status bar for “Streaming” with a green indicator
• On the receiving end, verify the stream is playing
• Monitor for dropped frames or reconnection events

Using SRT with a Streaming API

For developers building applications, you can use a live streaming API that accepts SRT ingest. LiveAPI supports SRT ingest natively — send your SRT stream to LiveAPI’s servers, and the platform handles transcoding, adaptive bitrate packaging, and CDN delivery via HLS.

// Create a live stream with SRT ingest via LiveAPI
const sdk = require('api')('@liveapi/v1.0#5pfjhgkzh9rzt4');
sdk.post('/streams', {
  name: 'SRT Production Feed',
  input_type: 'srt',
  quality: '1080p'
})
.then(res => {
  console.log('SRT ingest URL:', res.data.srt_ingest_url);
  // Use this URL in your SRT encoder
})
.catch(err => console.error(err));

This approach eliminates the need to manage your own SRT decoder, transcoder, and distribution infrastructure.

SRT Encoder Configuration Best Practices

Getting the most out of your SRT encoder requires tuning a few key parameters beyond the defaults.

Bandwidth Overhead

SRT adds protocol overhead on top of your video bitrate. A safe starting point is 25% overhead. If your video bitrate is 5 Mbps, ensure your network can handle at least 6.25 Mbps. In high-loss environments, increase overhead to 50-100%.

Formula: Required bandwidth = Video bitrate + Audio bitrate + (Total bitrate x Overhead %)

Connection Mode Selection

• Use Caller mode when your encoder pushes to a known server IP (most common)
• Use Listener mode when a server or decoder pulls from your encoder (useful when the encoder has a public IP)
• Use Rendezvous when both sides are behind NAT and neither can open a port

Bitrate and Resolution Matching

Match your video bitrate to your resolution and codec:

Encryption Settings

Always enable encryption for streams over the public internet. Use AES-256 with a passphrase of at least 10 characters. The encryption adds minimal latency (under 1 ms on modern hardware) and protects against stream interception.

Is an SRT Encoder Right for Your Project?

An SRT encoder is a good fit if:

• You need sub-second latency for remote production, sports, or interactive events
• Your streams travel over unreliable networks (cellular, satellite, public internet)
• You require encrypted transport without extra infrastructure
• You want to future-proof your pipeline with a codec-agnostic, open-source protocol
• You are building a live streaming application that needs reliable ingest from field encoders

An SRT encoder may not be the best choice if:

• Your destination platforms only accept RTMP and you cannot add a conversion step
• You need the simplest possible setup with no configuration tuning
• Your budget limits you to the cheapest hardware encoders (RTMP-only devices start lower)
• You are streaming only to social media platforms that handle ingest natively

For most professional and developer-focused workflows in 2026, SRT is the better default. If you are building on top of a streaming platform that supports both protocols, you get the flexibility to use SRT where it matters and fall back to RTMP where compatibility requires it.

SRT Encoder FAQ

What is an SRT encoder?

An SRT encoder is a device or software application that compresses video and transmits it using the Secure Reliable Transport (SRT) protocol. SRT uses UDP with ARQ error correction to deliver low-latency, encrypted video over the public internet. SRT encoders are used for live streaming contribution, remote production, and point-to-point video transport.

Is SRT better than RTMP for live streaming?

For contribution and ingest, SRT is better in most scenarios. SRT delivers 300-500 ms latency versus 1-3 seconds for RTMP, includes built-in AES encryption, and handles packet loss more efficiently. RTMP still has wider platform support for distribution, but SRT is rapidly becoming the industry standard for professional streaming.

Does OBS support SRT encoding?

Yes. OBS Studio supports SRT output natively. You can configure SRT by going to Settings > Stream, selecting “Custom,” and entering an SRT URL with parameters for mode, latency, and encryption. OBS supports caller, listener, and rendezvous modes.

What is the difference between SRT caller and listener mode?

In caller mode, the encoder initiates the connection to a remote listener (similar to how a web browser connects to a server). In listener mode, the encoder opens a port and waits for an incoming connection. Caller mode is the most common for pushing streams to a server. Listener mode is used when a server or decoder needs to pull from the encoder.

What latency should I set on my SRT encoder?

Set the SRT latency buffer to at least 2.5 times the round-trip time (RTT) between your encoder and the receiving server. For most internet connections, 120-300 ms is a good range. For cellular or satellite links with higher packet loss, use 500-1,000 ms. The default in most encoders is 120 ms.

Can I use SRT with H.265 (HEVC)?

Yes. SRT is codec-agnostic, meaning it can transport any video codec including H.264, HEVC, and AV1. The choice of codec depends on your encoder’s capabilities and your destination’s decoding support. HEVC offers better compression than H.264, which means higher quality at the same bitrate or equal quality at a lower bitrate.

What is the best hardware SRT encoder?

The best choice depends on your use case. The Haivision Makito X4 is the broadcast standard for multi-channel 4K HEVC contribution. The Epiphan Pearl Nano is a strong choice for single-channel remote contribution at a lower price point. The Teradek Vidiu X works well for mobile field streaming. For developers building API-driven workflows, using a software encoder with a cloud streaming API is often more practical.

How do I encrypt an SRT stream?

Set a passphrase on both your encoder and decoder. The passphrase must be at least 10 characters and must match exactly on both sides. Choose AES-128 or AES-256 key length (AES-256 recommended). In OBS, add passphrase=yourkey&pbkeylen=32 to your SRT URL parameters. On hardware encoders, configure encryption in the device’s web interface.

Can I convert SRT to HLS for web delivery?

Yes. SRT is a contribution protocol (encoder to server), while HLS is a distribution protocol (server to viewer). You need a media server or streaming platform that accepts SRT ingest and transcodes the stream into HLS for playback in browsers and mobile apps. LiveAPI handles this automatically — ingest via SRT or RTMP, and the platform delivers HLS with adaptive bitrate streaming.

Is SRT open source?

Yes. SRT is an open-source protocol released under the MPL-2.0 license. It was originally developed by Haivision and is now maintained by the SRT Alliance, which includes over 500 member organizations. The protocol’s source code is available on GitHub, and there are no licensing fees to use it.

Start Streaming with SRT

SRT encoders give you lower latency, built-in encryption, and better network resilience than RTMP — the three things that matter most when you are sending live video over the internet. Whether you choose a hardware encoder for field reliability or a software encoder for studio flexibility, SRT is the protocol that professional streaming workflows are standardizing on in 2026.

The fastest path from SRT encoder to global audience is pairing your encoder with a streaming API that handles the rest — transcoding, adaptive bitrate packaging, multi-CDN delivery, and player embedding. Get started with LiveAPI to send SRT streams from any encoder and deliver HLS to every device, with just a few lines of code.