Check that your camera works and see what it really delivers: a live preview, the resolution the browser negotiated next to the one you asked for, the measured frame rate, a lighting check, and a snapshot you can save.
Nothing opens until you press Start camera. The video stays in this tab and is never recorded or uploaded.
Press Start camera and the browser will ask for permission. The 1080p preset is selected; you can change it, or the camera, at any time.
Mirrored like a selfie view, so your right hand appears on the right. The other side of a video call sees the picture unmirrored, and snapshots are saved unmirrored unless you choose otherwise.
Changing either one while the camera is live restarts the stream on the new settings.
Browsers treat a size as a wish. Start the camera to see whether this one was granted, or quietly negotiated down.
Each frame is timestamped as it arrives, over a rolling two-second window.
Start the camera to measure the frame rate it really delivers, rather than the one it reports.
Twice a second, a 64 × 36 copy of the frame is averaged for brightness.
Start the camera to check whether the picture is too dark, dim, well lit, or overexposed.
Start the camera to read the size and frame-rate ranges it advertises to the browser.
Captured at the full delivered resolution, kept in this tab, and saved only when you download it.
Start the camera, then press Take snapshot. The frame is captured at the delivered resolution and stays on this device until you download it.
Every figure here is what this browser and this camera agreed on. The camera's own app, or a native app using a different driver path, may reach a higher resolution or frame rate than a browser is offered.
USB 2.0 ports, hubs, and long cables limit how much video gets through, and auto exposure in dim light lengthens every frame. A rate below the reported one usually points to one of those rather than a faulty camera.
Nothing is recorded or uploaded, and the page makes no network request with your video. A snapshot stays in this tab until you download it and is discarded when you leave the page.
The frame rate is measured from frame timestamps over a rolling 2-second window, and needs 8 frame intervals before it shows a figure, or 2 spanning 1.5 seconds for a slow camera. A gap of 1 second or more starts the window again, and the figure is cleared until frames return. Brightness is the mean Rec. 709 luma of a 64 × 36 copy of the frame, read every 500 ms. Pressing Stop camera, switching camera or size, or leaving the page stops every track, which is what turns the camera light off.
getUserMedia does not open a camera at a size; it hands the browser a wish list. The browser compares that list with the modes the camera offers, picks the closest one it can run, and starts the stream without saying what it gave up. This page asks for the size you choose, reads back what was negotiated from the track settings and from the frames themselves, times every frame as it arrives, and samples the brightness of the picture twice a second. All of it happens in this tab.
Press Start camera and choose Allow when the browser asks. Nothing opens before you click, and if access was blocked earlier the page names the setting to change, in the browser and in macOS or Windows privacy settings.
Choose a built-in or USB camera from the list, then a resolution preset. The panel beside the preview shows the size you asked for next to the size the camera actually delivered, which is often smaller.
Check the measured frame rate, the frame jitter, and the lighting verdict. Take a snapshot to keep a still at the full delivered resolution as PNG or JPEG, then press Stop camera so the light goes out.
Browsers treat a resolution as a wish, not an order. The page asks for the size you pick and reports the one the camera settled on, from both the track settings and the frames themselves, so a silent downgrade is in plain view.
Frames are timestamped as they arrive with requestVideoFrameCallback and turned into a rolling two-second rate, the mean frame interval, the jitter, and an estimate of frames missing against the rate the camera reports.
Twice a second a 64 × 36 copy of the frame is averaged for brightness. The verdict reads too dark, dim, good, or overexposed, and the advice connects dim light to the frame rate it costs.
Built-in cameras, USB webcams, capture cards, and virtual cameras are listed by name once access is granted, and the list refreshes by itself when a camera is plugged in or removed.
A mirrored preview by default, like a selfie view, a rule-of-thirds grid for framing your face, and a full-screen view for checking focus and grain up close.
A still is captured at the delivered resolution and kept in this tab until you download it as PNG or JPEG. It is saved unmirrored by default, the way other people see you, with a mirrored option.
Start the test and read the message it gives, because each failure has a different fix. Access was blocked means the browser or the operating system refused, and the fix is in the address bar or the privacy settings. No camera was found means it is unplugged, disabled in Device Manager or System Settings, or switched off by a hardware key. The camera could not start means another app is holding it. If the preview opens but stays black, look for a sliding privacy shutter over the lens; the lighting reading will sit near zero when the lens is covered.
Many cameras can be opened by only one program at a time, particularly on Windows. Zoom, Microsoft Teams, a Google Meet tab, OBS, FaceTime, and the manufacturer's own camera utility can all hold it, sometimes from the system tray after their window has closed. Quit them fully, close other tabs that used the camera, and press Try again. Unplugging and reconnecting a USB webcam also clears a driver that has stuck.
In Chrome and Edge, click the site settings icon at the left of the address bar, set Camera to Allow, and reload. In Safari on a Mac, open Safari, Settings, Websites, Camera, and set this site to Allow. In Firefox, click the camera or permissions icon in the address bar, remove the block, and try again. If the browser allows it and the test still fails, the operating system is refusing: on macOS open System Settings, Privacy & Security, Camera, and switch your browser on; on Windows open Settings, Privacy & security, Camera, and turn on camera access and the access for desktop apps.
Because a mirrored view is what people expect when they look at themselves: it behaves like a mirror, so moving left moves left on screen. This page mirrors the preview by default for that reason, and the Mirror toggle turns it off. The camera itself is not mirrored. People on the other side of a video call see you the right way round, so writing on a shirt or a page you hold up reads correctly for them even though it looks backwards to you. Snapshots are saved unmirrored for the same reason.
A size in the browser is a request the camera can quietly decline, and three things usually decline it. The browser chooses among the modes the camera offers and may settle lower; with no size requested at all, Chrome and Firefox usually open a camera at 640 × 480. The connection may not carry it: uncompressed 1080p at 30 frames per second needs far more than USB 2.0 can move, so cameras depend on compression for full HD, and a busy hub or a long extension cable pushes them down. And the app at the other end may cap it, since most video calls send 720p or less. Choose 1080p here and compare requested with delivered to see which side is the limit.
Auto exposure. When light is short, the camera keeps each frame exposed for longer to gather it, and a frame cannot arrive faster than its exposure: a 1/15 second exposure caps the rate at 15 frames per second however fast the camera is rated. Many webcams do this on their own in dim light, which is why the measured rate here can sit well below the reported one while the picture still looks bright enough. Put light in front of you, not behind, and watch the measured rate climb back.
Less than most cameras offer. Zoom, Microsoft Teams, and Google Meet send 720p or less for most calls, lower again in a gallery view or on a weak connection, and 1080p only on particular plans, meeting types, or settings. About 30 frames per second is the usual target. A camera that delivers a steady 720p at 30 frames per second is therefore enough for calls; a 4K webcam mainly helps with framing, digital zoom, and recording or streaming, where its full output is used.
No. The video goes from the camera into this tab and nowhere else: nothing is recorded, nothing is uploaded, and the page makes no network request with any frame. The measurements are arithmetic on frames already in memory. A snapshot stays in this tab until you download it and is discarded when you leave the page. Press Stop camera, or close the tab, and every track is stopped.
Plug the webcam straight into the computer rather than through a hub, then start the camera. Once access is granted the picker lists every camera by name, including built-in cameras, USB webcams, capture cards, and virtual cameras created by apps such as OBS, and it refreshes by itself when one is plugged in or removed. Select the external one and the stream restarts on it; the delivered resolution and frame rate then show whether the cable and port are keeping up. Each app chooses its own camera, so set it in your call app's settings as well.
On most cameras the light is tied to the sensor being powered, so it stays on while any program holds the camera open. This page stops every track when you press Stop camera, switch camera or resolution, or leave the page, and the light should go out within a second or two. If it stays on, something else has the camera: another tab, a call app running in the background, or a manufacturer utility. On a Mac, Control Center in the menu bar names the app using it. On Windows 11, Settings, Privacy & security, Camera lists the apps that used it recently.
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