Is SRT or RTMP better for IRL streaming?

SRT is the better default for IRL over cellular: it retransmits lost packets on the single link and adds encryption. RTMP is simplest on a stable connection.

What's the difference between SRT and SRTLA?

SRT carries your stream over a single connection. SRTLA does the same but bonds multiple connections at once (e.g. two or three SIMs) into one resilient stream — if one drops, the others keep it running.

Can Twitch or YouTube ingest SRT or SRTLA directly?

No — they take RTMP. Send SRT or SRTLA to a relay or OBS, which then outputs RTMP to the platform.

What's the actual latency difference between SRT and RTMP?

Both can run at roughly 1-3 seconds glass-to-glass on a good connection. The real difference shows up under packet loss: RTMP stalls and rebuffers, adding seconds of delay per drop, while SRT's tunable latency buffer (typically 200ms-4000ms) absorbs the loss without a visible freeze.

Is RTMP/SRT (using both) even possible in one stream?

Not in a single connection — each stream uses one protocol at a time. But your encoder app can offer both as connection options, and a relay like StreamRelay accepts either, so you can switch protocols between streams without changing anything else in your setup.

SRT vs. SRTLA vs. RTMP: Which Is Better for IRL Streaming?

When you stream live from out and about, your phone (or an encoder — an app or small device that turns your camera into a stream, e.g. Moblin, IRLPro or Larix) sends video to OBS on your home PC through a relay (a middleman server that catches your stream and hands it on). The “protocol” you pick is simply the language your phone and the relay use to talk to each other — and it changes how your stream behaves when the network gets shaky. Here are the three main choices — SRT, SRTLA and RTMP — compared for exactly this job, plus which one to use with your StreamRelay endpoint.

SRT vs SRTLA vs RTMP at a glance

	RTMP	SRT	SRTLA
Latency	Low	Lower (tunable)	Lower (tunable)
Recovery on packet loss	Stalls / reconnects	ARQ retransmit on the link	ARQ retransmit, across bonded links
Connection bonding	No	No (single connection)	Yes — combines multiple connections
Encryption	No (RTMPS adds TLS)	Built-in AES	Built-in AES
Setup	Paste-and-go	A few params (latency, stream id)	Same as SRT, plus a bonding/modem setup
App support	Universal	Wide and growing	Growing (dedicated SRTLA-capable apps/senders)
Best for	Stable connections	Variable / cellular connections, single link	Moving through dead zones, tunnels, driving — needs multiple links

What is RTMP?

RTMP (Real-Time Messaging Protocol) is the old, reliable workhorse of streaming — it’s been around for years and almost everything speaks it. It’s simple: you paste in a server address and a key, hit go, and you’re live.

Strengths of RTMP

Supported by virtually every encoder and app — it just works everywhere.
Zero tuning needed — paste it in and go.
Fast and predictable when your connection is stable, like wired internet or strong Wi-Fi.

Limitations of RTMP

It insists on receiving every piece of video in order, so if a piece goes missing your stream pauses while that piece is re-sent — you see a freeze.
No built-in encryption (a version called RTMPS adds it, but not every app or platform supports RTMPS).
It struggles on mobile data, where little drop-outs are normal.

What is SRT?

SRT (Secure Reliable Transport) is the newer protocol, built specifically for pushing live video over the unpredictable public internet — exactly the conditions you face streaming from a phone on the move.

Strengths of SRT

ARQ is its trick for dealing with a flaky network: when a bit of video goes missing on the way, SRT quietly asks for it again and slots it back in, so brief drop-outs don’t freeze your picture.
Built-in AES encryption — your stream is scrambled so others can’t snoop on it, no extra setup required.
Tunable latency: you can tell it to wait a little longer before playing, which gives it more time to fix problems. More delay, but a smoother stream.

Limitations of SRT

A little more setup than RTMP — you set a latency value (how long it’s allowed to buffer) and a stream id (a label that tells the relay which stream is which).
Platforms like Twitch and YouTube can’t receive SRT directly — they only take RTMP. So you need a relay or OBS in the middle to translate, which is exactly the setup you’re building here.
Plain SRT still runs over a single connection — if that one connection drops out completely, the stream drops with it.

What is SRTLA?

SRTLA (SRT Transport Proxy with Link Aggregation) is an extension of SRT built for exactly the moment plain SRT can’t help: when your one connection dies completely. Instead of relying on a single network path, SRTLA bonds multiple connections at once — for example two or three phone/LTE modems, or Wi-Fi plus cellular — into a single, more resilient stream. If one connection drops or slows down, the others carry the stream while it recovers.

Strengths of SRTLA

Connection bonding — combines several links into one, so total drop-outs on one link don’t take your whole stream down.
Keeps all the SRT benefits: ARQ error recovery, built-in AES encryption, tunable latency — just applied across bonded links instead of one.
Built for the hardest IRL conditions: moving vehicles, tunnels, dead zones, crowded venues with unreliable cellular.

Limitations of SRTLA

More setup than plain SRT — you’re managing multiple network connections (several SIMs/modems) instead of one.
Overkill if a single connection already holds up fine — added complexity and cost (extra SIMs/data plans) for no real benefit.
Same platform limitation as SRT: Twitch/YouTube don’t ingest SRTLA directly, so it still needs a relay or OBS in the middle.

Head-to-head comparison

SRT vs RTMP latency: the actual numbers

Latency is delay: how long it takes from something happening in front of your camera to viewers seeing it. On a clean, stable connection, RTMP and SRT land close together, typically 1-3 seconds glass-to-glass (camera to viewer’s screen), plus whatever the platform (Twitch, YouTube) adds on top.

The gap shows up once the network gets messy, which for mobile IRL streaming is most of the time. RTMP has no way to recover lost data mid-stream. When a packet goes missing, the player has nothing to show until it’s re-sent, so you get a stall or a frozen frame, often a full second or more per drop. SRT handles this differently: it runs a small tunable latency buffer, usually set somewhere between 200ms and 4000ms, that holds a short window of video in reserve. When a packet is lost, SRT’s ARQ mechanism quietly re-requests it and slots it into that buffer before playback catches up. The viewer sees smooth video instead of a freeze. The cost is that same buffer: a higher latency setting means more delay, but more room to absorb loss without it showing.

On rock-solid Wi-Fi, RTMP’s simplicity wins and the latency gap barely matters. On cellular with any packet loss, which is the normal case moving around outdoors, SRT’s buffered recovery keeps the stream watchable for a small, predictable delay cost, while RTMP’s stalls are unpredictable and can pile up.

Reliability on unstable mobile networks

This is where SRT shines. Thanks to ARQ, when a packet (a small chunk of your video) gets lost on your mobile connection, SRT re-requests it over that same connection and patches the gap — so a quick signal hiccup doesn’t freeze your scene the way RTMP would. That’s recovery over a single connection. If your connection doesn’t just hiccup but drops out entirely — driving through a dead zone, a tunnel, a crowded venue — that’s where SRTLA takes over: it bonds several connections together, so the others carry the stream while one recovers or reconnects.

Encryption and security

SRT encrypts your stream out of the box with AES (a strong, standard way of scrambling data). RTMP doesn’t — you’d need the RTMPS variant for that, and RTMPS isn’t supported everywhere.

Encoder app support

RTMP works in every app. SRT is supported by Moblin, Larix, IRLPro and OBS — in other words, all the apps you’d actually use for IRL streaming. SRTLA support is growing fast too, with dedicated senders and the same major apps adding bonding modes.

Which should you use?

Pick SRT if…

You stream over mobile data or any connection that comes and goes, you want low delay, or you want your stream encrypted — and a single connection is good enough. This is the best default for most IRL streaming.

Pick SRTLA if…

You’re moving through spots where no single connection holds up — a driving vehicle, tunnels, dead zones, or crowded venues — and you can run multiple connections (e.g. two or three SIMs) at once to bond together.

Pick RTMP if…

Your connection is rock-solid (strong Wi-Fi or wired), or your app or workflow only supports RTMP, or you simply want the easiest paste-it-in-and-go path with nothing to configure.

All three work with your StreamRelay endpoint

StreamRelay accepts RTMP, SRT, and SRTLA. Use plain SRT for the simple single-connection case, or connect via SRTLA when you need multiple connections bonded into one resilient stream. Whichever protocol you pick, the relay carries that stream from your device into OBS.

Latency, DE-CIX Frankfurt and why location matters

Whichever protocol you choose, the biggest factor in delay is plain geography — how far your video physically has to travel and how directly it gets there. You choose your relay location in the dashboard. Today that’s DE-CIX Frankfurt, one of the world’s largest internet exchange points (a major hub where networks meet and hand traffic over) — with more EU locations on the way. That means EU traffic takes a short, well-connected route. It’s also GDPR-compliant (built to the EU’s data-protection rules) and EU-hosted, and your stream keys stay yours.

Keep reading

Ready to set it up? Follow the phone-to-OBS guide or the OBS setup guide. New to IRL? Start with the complete IRL streaming guide.