How to Send a Live Stream to an SRT Destination
SRT destinations need a few more details than RTMP: a mode, a host and port, and often a stream ID, passphrase and latency. Here's what each part of an srt:// URL means and how to get a stream connected.
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To send a live stream to an SRT destination, get an srt:// address from the receiver, confirm which side listens and which side calls, and match the stream ID, passphrase and latency the receiver expects. Then open the receiver's UDP port, start the sender and check that video arrives before relying on it.
Small mismatches break SRT setups, so match every detail. New to the protocol? Start with what SRT streaming is.
Key takeaways
- One side of an SRT connection listens on a UDP port and the other calls it.
- An srt:// URL carries host and port plus options like mode, streamid and passphrase.
- Most failures come from a closed port, two callers, or a passphrase or stream ID mismatch.
- Test locally before pointing a 24/7 stream at a production receiver.
Who actually uses SRT destinations
You won't usually send SRT to a mainstream social platform. SRT destinations tend to be systems that a broadcaster, company or partner runs:
- Broadcast playout and production. Studios receive contribution feeds over SRT into hardware decoders, switchers and playout systems.
- Media servers. Self-hosted and commercial media servers accept SRT and repackage it for players, recording or further distribution.
- Partner handoffs. A channel supplying programming to a network, venue screens or a distributor often delivers it over SRT.
- Cloud video services. Some professional platforms offer SRT ingest alongside RTMP.
In each case, the receiver's operator gives you connection details to match exactly. If the far end only offers RTMP, follow the custom RTMP server guide instead.
Caller, listener and rendezvous modes
Every SRT connection needs one side that waits and one side that dials.
- Listener binds to a UDP port and waits for connections. It needs a reachable address and an open firewall port.
- Caller connects to a listener's host and port, and works from behind most firewalls because the connection is outbound.
- Rendezvous has both sides call each other at once on agreed ports, which can help when neither side accepts inbound traffic.
Mode is unrelated to which way video flows. When a cloud service or encoder delivers to your server, the usual arrangement is sender as caller and receiver as listener.
The classic mistake is two callers or two listeners. Both sides wait with no clear error, so confirm the mode with the receiver's operator.
Reading an srt:// URL piece by piece
An SRT address usually looks something like this:
srt://ingest.example.com:9000?mode=caller&streamid=channel-main&passphrase=YOUR-LONG-SECRET
- Host and port. The receiver's hostname or IP address and the UDP port it listens on. There's no universal default port, so use the one you're given.
- mode. Your side's role: caller, listener or rendezvous.
- streamid. An identifier some receivers use to route or authorize a feed, similar to a stream key. Its format depends on the receiver.
- passphrase. The shared secret for AES encryption, commonly required to be 10 to 79 characters. Both ends must match exactly.
- pbkeylen. Optional key length of 16, 24 or 32 bytes, meaning AES-128, 192 or 256.
- latency. The recovery buffer. Some tools take milliseconds while FFmpeg-based software commonly expects microseconds, so check before copying a number from another setup.
Preparing the receiving end
If you run the receiver yourself, prepare it before anything is sent:
- Set up a listener on a fixed UDP port in your media server, decoder or playout software.
- Open that UDP port in the server firewall and in any cloud security group or router in front of it. TCP rules don't cover SRT.
- Choose a passphrase and, if your software routes by stream ID, an ID for this feed.
- Pick a latency that suits the path; long or unstable routes need more.
- Confirm the format. SRT typically carries MPEG-TS with H.264 video and AAC audio, so make sure the receiver accepts it.
- Test locally by sending a short feed from OBS or FFmpeg on another machine.
If the receiver only accepts approved addresses, allow the sender's too.
Troubleshooting SRT connections that won't start
SRT errors are often vague, so diagnose by symptom:
- Connection times out. The UDP port is closed or not forwarded, the host is wrong, or both sides use the same mode.
- Connection is rejected. Usually a passphrase mismatch, a passphrase set on only one side, or a stream ID the receiver doesn't recognize.
- Connects, then stutters or drops. Latency is too low for the network path, or bandwidth is below the bitrate plus retransmission overhead. Raise latency first.
- Connects with no picture or sound. The receiver expects a different container or codec, and its logs usually say which.
Once it works, record every value that connected. The broader habits in keeping a 24/7 stream online apply to SRT destinations too.
Adding an SRT destination to a StreamHouse stream
In StreamHouse, SRT is a custom destination alongside the built-in platforms. Paste the receiver's full srt:// URL, including options it requires such as a passphrase. If you were given a stream ID or key separately, enter it in the stream ID field, and StreamHouse adds it as the streamid parameter when the URL doesn't already contain one. Without a mode in the URL, StreamHouse connects as the caller, so your receiver should listen.
Send a looping playlist of pre-encoded videos to your receiver around the clock, or add SRT next to YouTube, Twitch and other RTMP destinations on the same stream without using extra stream slots. It runs in the cloud and reconnects automatically after hiccups. The getting-started guide walks through a first stream.
Frequently asked questions
What port does SRT use?
There's no single standard port. The listener can use any available UDP port, and the receiver's operator tells you which one. That port must be open for UDP traffic in every firewall between the sender and the listener.
Should my SRT sender be the caller or the listener?
Usually the sender calls and the receiver listens, because receivers tend to have fixed addresses and open ports while senders sit behind firewalls. Either works technically, as long as the sides use opposite modes or both use rendezvous.
What latency should I set for SRT streaming?
A common starting point is several times the round-trip time between sender and receiver, increased for lossy or long-distance links. Start conservatively, watch for dropped packets, then lower it gradually. Confirm whether your tool expects milliseconds or microseconds.
Can I send SRT and RTMP from the same stream?
Yes, if your tool supports multiple outputs. A cloud service can deliver RTMP to public platforms and SRT to a private receiver at the same time, with no extra upload from your connection. Each destination still needs its own correct details.
