How a pre-motion clip works
Most motion recorders start recording at the moment they notice movement, which means the clip often begins with someone already halfway across the frame. Webcam Motion Detector keeps a rolling buffer of the last few seconds at all times. When motion is detected, that buffer becomes the start of the clip.
Recording then continues for as long as there is movement, plus a run-on you choose, from 5 seconds to 2 minutes after the last change. A person who pauses and moves again within that time stays in one clip instead of three.
Motion is measured as how much of the picture changes between frames. Turn on the outline while you set it up and you can see exactly what it reacted to, then raise or lower the sensitivity until a passing shadow is ignored and a person is not.
How to set up webcam motion detection in Windows
Webcam Motion Detector works with any camera Windows can see, built-in, USB or a capture device. A few settings on one page decide what counts as motion and what gets saved.
- Choose the camera by name. The app remembers it across restarts.
- Set the sensitivity to Low, Medium or High, and turn on the outline to see what it reacts to.
- Set the head start, from 0 to 10 seconds, and how long it keeps recording after the last movement, from 5 seconds to 2 minutes.
- Pick the folder for clips, whether they are named by date and time or numbered, and whether an alarm sounds.
- Start watching, then close the window. It keeps watching from the notification area.
Watching your webcam motion detector from a phone
Scan the code in the app with your phone's camera and the phone shows the camera live, with no app to install and no account. From that page you can start or stop watching, see when motion last happened with a snapshot of it, and see how many clips your PC has saved since the app started.
On the same Wi-Fi as your PC the picture runs at about 15 frames a second, and a few a second on mobile data. While the phone view is open, the app on your PC says "Watched on phone", so nobody in the room is watched without knowing.
Where a webcam motion detection recorder keeps its clips
Clips are saved as ordinary H.264 MP4 files in a folder you choose. They play in anything, and you can keep them, move them or delete them like any other file.
Each clip is recorded at the camera's own resolution, or at a fixed 480p, 720p or 1080p if you prefer. A mirror switch flips the picture for a camera pointed back at you.
Limits to know before you rely on it
Clips are video only, with no sound. The app keeps your PC awake while it is writing a clip and lets go when it finishes, so set Windows' own sleep timer if the PC needs to stay awake between clips.
The phone buzzes on motion only while the phone page is open. Close it and your PC keeps recording as usual. Windows may also ask you once, in Settings, to allow camera access for desktop apps, and that is the only permission involved.
