What is SRTLA, and why does IRL streaming need it?

SRT is a streaming transport that handles packet loss gracefully over lossy networks. It came out of broadcast and became the de facto standard for contribution video over the public internet. SRT is great over a single link. What if you have several?

That is where SRTLA comes in. SRTLA stands for SRT Link Aggregation. The idea is simple: you take one SRT stream and split it across multiple network links. The receiver reassembles the packets. If one link drops, the others carry the stream. If one link gets congested, the sender can lean harder on the healthier links. The useful throughput is roughly the sum of the working links, minus some overhead.

Why this matters for IRL

Cellular networks lose packets, change routes, and get crowded. A single 5G modem can look perfect for ten minutes, then stall when you turn a corner or walk into a packed venue. With one modem, the stream has nowhere else to go. With several links on different carriers, SRTLA can keep sending over the links that are still working.

How it works in IRLEncoder

Plug in your modems, your ethernet, and any tethered phones. Pick a relay that speaks SRTLA. Pick a bonding mode and a bitrate algorithm.

SRTLA modes (how the stream uses your links):

• classic: like the original BELABOX setup.
• enhanced: the default. Skips bad links and uses the good ones. When a bad link gets better, it comes back.

Bitrate algorithms (how quickly video quality changes):

• auto: the default. Pays attention to your modem signal and how hot the device is, then picks a safe bitrate.
• bela: the original BELABOX style, in case you want it.
• fight: pushes harder, recovers faster, takes more risk.

Switch any of these while live. Watch the bonded link diagram. You will see which link is doing the work.

What about Reed-Solomon, FEC, retransmits?

SRT asks the receiver to resend missing packets. SRTLA gives SRT more than one network path to try. On top of that, IRLEncoder sends a small amount of extra repair data with the stream. If a packet goes missing, the receiver can rebuild it from what arrived instead of asking again. When links are clean, the cost stays low. When loss picks up, the repair data picks up with it.