NDI vs USB Capture — The Latency Test Streamers Need

NDI is sold as the latency-free network capture protocol. USB capture is sold as zero-latency. Both claims are oversimplified. Here is what we measured.

In our test rig (1 Gbps wired LAN, OBS 32 receiving from a phone-as-NDI-source), NDI HX3 latency averaged 35ms end-to-end. USB capture latency on the same source rig (Elgato 4K X) measured 18ms. So USB wins on raw latency — but the variance on USB was higher (12-28ms), while NDI was tighter (32-39ms).

The practical takeaway: for vertical streaming workflows where the second source is a phone that needs to move around, NDI’s flexibility wins. For an absolute lowest-latency competitive setup with a fixed second camera, USB capture is genuinely faster. Both are usable; the choice is workflow-driven.