Description
About Camera Preview Delay Check
Introduction
Camera Preview Delay Check compares live webcam motion to real-world cues so you can sense whether local self-view feels snappy or clearly behind. Browsers do not expose true sensor-to-display latency, so this is a visual delay aid, not a lab meter.
What this tool does
It opens a local getUserMedia preview and guides a hand-wave or clock comparison. Any on-page delay figure is best-effort and may read N/A when APIs cannot support a meaningful number. Switch cameras or USB ports to compare relative feel.
When to use it
Use it when self-view feels late, when ranking webcams or capture paths, and when you need to know whether meeting-app lag is local preview versus encode/network. Prefer Camera FPS Test for hitching, Webcam Test for a plain preview.
How it works
Frames reach an HTMLVideoElement through the browser media pipeline. requestVideoFrameCallback can timestamp presentation but not ISP or USB delay inside the camera. Without specialized hardware, web pages only support coarse visual comparison. HTTPS and camera permission are required.
Step-by-step instructions
- Open Camera Preview Delay Check and allow camera access.
- Keep the tab focused and wave a hand or hold a phone stopwatch to the lens.
- Judge whether the preview trails real motion noticeably.
- Retry with another camera or USB port, then stop the stream when finished.
Common problems
Expecting absolute milliseconds from a web page leads to frustration; use relative rankings. Heavy CPU load, wireless displays, and virtual cameras add delay. If meetings feel worse than this page, encode and network delay are likely on top of local preview.
Privacy explanation
Preview stays local. DeviceHub does not upload or record video. Stop ends tracks; revoke camera access in site settings anytime.