Explainer · Engineering
Fixed vs drifting latency: why multicam falls out of sync.
"As fast as possible" sounds like the right goal for a live camera. In a multicam it's exactly wrong — what you want is a delay that's known and constant, on every camera, all show long.
The problem
Put two wireless cameras on the same subject and cut between them. If camera A is slightly behind camera B, every cut jumps backwards or forwards in time — a clap lands twice, a ball teleports, lips drift against the audio. The classic broadcast fix is simple: delay every camera to match the slowest one. But that only works if each camera's delay is a number you actually know — and that stays put.
Why latency drifts
A "lowest possible latency" pipeline is an elastic one. Its buffers grow when Wi-Fi stutters and shrink when it recovers; the encoder queues more or fewer frames depending on the scene. The result is a delay that's different every second — you can't align cameras against a moving target. That's the classic sync complaint in ad-hoc wireless multicams: each source is fast on average and unpredictable in the moment.
The fixed-delay approach
Airlive treats latency as a setting, not a race. Each camera runs a latency preset — from Unbuffered to Smooth — and the pipeline holds that delay steady: the buffer absorbs network hiccups instead of passing them on as timing changes. Set the same preset on every camera and the whole multiview moves in lockstep; cuts are clean because every source is equally "late".
Latency preset picker in the source settings (Unbuffered → Smooth).
How to choose a preset
- Conversation, IRL, camera-switching on the beat — lean low (toward Unbuffered), as low as your worst Wi-Fi moment allows.
- Music, critical AV sync, busy venues — lean smooth; a slightly larger but rock-steady delay is invisible to viewers, drift is not.
- Rule of thumb: rehearse at a low preset, watch for stutter, step up one notch — then set every camera to the same value and stop touching it.
FAQ
What number is "good latency"? Whichever one stays constant. A fixed delay is something you can plan a production around; a fluctuating "fast" one isn't.
Can I mix presets across cameras? You can, but for multicam you shouldn't — matching presets is what keeps the cut coherent. Solo camera into OBS? Pick whatever feels best — the OBS setup guide covers it.
Where do I set this? In the source properties of the OBS plugin, or per channel in Bridge.