Your studio accepts plain SRT, and not yet SRTLA. Apps that can send SRTLA can also send plain SRT: in Moblin or
IRL Pro, enter the address of your input the way the studio shows it, beginning with srt://. The app then sends
over one connection instead of several bundled ones.
SRTLA bonding is planned. Until then, what this page says applies.
What SRTLA is
SRTLA stands for "SRT Link Aggregation". The sender spreads the packets of one SRT stream over several connections, for example two SIM cards and a Wi-Fi network. The receiver puts them back together into one stream. When one connection gets weak, the others carry more. When one fails, the stream goes on over the rest.
The method comes from the BELABOX project and is open. It needs two sides: a sender that spreads the packets, and a receiver that understands SRTLA. A receiver for plain SRT cannot do anything with the packets of an SRTLA sender.
What works today
| Sender | Plain SRT | SRTLA |
|---|---|---|
| Moblin (iOS) | works | not yet |
| IRL Pro (Android) | works | not yet |
| BELABOX | the encoder does not send it | not yet |
The BELABOX encoder always sends SRTLA, even with a single modem. That is why it cannot send to your studio directly today.
How to switch the app over
Moblin. The QR code on the “Inputs” tab sets up plain SRT; there is nothing to change. See
Connecting Moblin with a QR code. If you enter the address by hand, its beginning decides:
srt:// is plain SRT, srtla:// is bonding. Take the address from the studio unchanged.
IRL Pro. Choose SRT as the protocol, not SRTLA, and enter host, port and stream ID from the address of your input.
The address is on the “Inputs” tab under “Connect source” and has the form
srt://<host>:<port>?streamid=<id>. There is no passphrase; the field stays empty.
How to tell that SRTLA is still selected
| What you see | What you do |
|---|---|
| The app keeps trying to connect, and the input stays on “No signal” | Check that the address begins with srt:// and that SRT is chosen as the protocol. |
With srt:// it still says “No signal” |
SRTLA is not the cause. Go on with No picture in the studio. |
An SRTLA sender first registers its connections, and your studio does not answer that. The app therefore shows no error that names SRTLA. It waits.
What helps on a single connection
| Measure | What it does |
|---|---|
| More SRT latency in the app | SRT gets more time to ask for lost packets again: 500 to 1000 ms on good mobile data, 1500 to 2000 ms on bad. See Setting the SRT latency. |
| Adaptive bitrate in the app | The app sends less when the network carries less, instead of losing packets. |
| A fallback scene | When the bitrate collapses or packets are lost for good, your studio cuts to "be right back" after two to three seconds, and back later. See Switching to “be right back” automatically. |
| Changing the network by hand | When you switch the phone from Wi-Fi to mobile data or to the second SIM, the SRT connection breaks and the app connects again. |
Through all of this the stream to Twitch or YouTube stays online. Your studio keeps sending even while nothing arrives from your camera: with the fallback scene if you have set one up, otherwise with your overlay.
If you need bonding now
If you regularly travel through areas where no single network holds, you need a receiver that speaks SRTLA today. Those are relay services or a server of your own. What there is, is described in IRLHost and IRLServer compared (in German).