Guides · 5 min read
What is SRTLA? Bonding for IRL streams, explained
One stream, two networks. SRTLA is how IRL streamers stop a dead spot from ending the broadcast.
SRT first
SRT, short for Secure Reliable Transport, is the protocol most IRL apps send video over. When a packet goes missing on the way, the receiver asks for it again, and it has until the latency you set to arrive. On a weak connection, a lost packet becomes a resend rather than a frozen picture.
RTMP, the older protocol, has no such window. On a solid connection it is fine; on a weak one it falls behind and stutters.
What the LA adds
SRTLA stands for SRT link aggregation. It was built by the BELABOX project and is open source.
Your app splits the stream across every connection it has and sends more down the ones that are coping best. At the other end, a receiver puts the pieces back in order as one ordinary SRT stream. If one connection fails, the others carry the stream on.
Because the connections add together, two that could each hold roughly half a stream can carry all of it between them. That is what IRL streamers mean by bonding.
What you need
- Two or more connections, ideally on different networks. Two connections on the same network share the same towers, so when one is struggling the other usually is too.
- On a phone, that usually means its own mobile data plus Wi-Fi from a pocket hotspot with a SIM on another network.
- A bonding box such as BELABOX takes several USB modems, each with its own SIM.
- An app that speaks SRTLA. Moblin on iPhone does, and so does BELABOX. In any other app, look for SRTLA or bonding in its settings.
- A receiver at the other end. Streaming platforms do not take SRTLA themselves, so something has to put the stream back together before it goes on.
Setting it up on the LIVE Toolkit
The toolkit runs the receiver for you. Its Feed tab shows an SRTLA address beside the SRT one, and the relay that takes it hands your cloud OBS one camera, however many connections it arrived on.
In Moblin, the Open in Moblin button already uses the SRTLA address: tap it on the iPhone, or scan its QR code from a computer, and the stream is set up to bond. Then give the phone its second connection, for example by joining a hotspot's Wi-Fi with mobile data still on.
In BELABOX, copy the host and the SRTLA port into their own fields and paste the same stream ID. The guide to connecting your app has every app's boxes, step by step.
Latency, the one setting to know
SRT's latency is how long the receiver waits for a lost packet before giving up on it. Higher gives a weak connection more time to recover, and adds the same delay to everything you send. Your app's default is a sensible start; raise it if the picture breaks up on a bad network.
What bonding cannot do
Bonding adds connections together; it cannot make signal where there is none. If every network you carry drops at once, the feed stops like any other. The toolkit then shows your BRB screen and switches back once the feed has been steady again.
On Pro you can go further with a second phone on another network: if the phone on air drops, a steady one goes on air instead of the BRB screen.
Common questions
Is SRTLA the same as SRT?
No. SRT runs over one connection. SRTLA spreads SRT across several at once and puts it back together at the other end.
Do I need two SIM cards?
You need two connections, ideally on different networks. On a phone that can be its own mobile data plus a Wi-Fi hotspot on another network; a bonding box takes several modems with a SIM each.
Can I send SRTLA straight to Twitch or Kick?
No. You need a receiver in between. The LIVE Toolkit's relay takes SRTLA, puts the stream back together and hands it to your cloud OBS, which streams to Twitch, Kick or YouTube.
Does SRTLA work with HEVC?
Yes. SRTLA carries whatever your app encodes, and the LIVE Toolkit takes HEVC over SRT and SRTLA.
Last reviewed October 4, 2026. Rates in this guide are the live ones, not a snapshot.