摄像头遮挡检测器

When a camera will not show video, the cause is usually one of four different things — a browser permission block, an OS-level privacy block, a driver or hardware conflict, or a genuine physical lens cover — and each needs different guidance. This runs an actual sequence of checks and tells you which one you are dealing with, rather than guessing from a single symptom.

摄像头已关闭

检查项

诊断步骤

1. 浏览器权限状态：检查中…

—

2. 摄像头视频流测试：等待中

点击上方的「运行完整诊断」开始。

3. 画面内容检查：等待中

在视频流检查成功后运行。

说明

每种结果的真正含义

浏览器权限被拒绝浏览器本身正在阻止访问。可通过地址栏中的摄像头图标或浏览器自身的隐私设置来修复。

操作系统级阻止（浏览器显示已授权，视频流仍然失败）The most commonly missed cause — an operating-system privacy toggle sitting behind an already-granted browser permission. Check your OS's camera privacy settings directly.

未找到设备硬件 or driver issue — the browser cannot see any camera at all. Check cables, Device Manager, or whether the camera is disabled in the OS.

无法启动（正在使用中）Almost always another application already holds the camera open. Close other video apps and tabs first.

画面开启但看起来被遮挡Permission and stream both succeeded, but the image itself is near-uniformly black — consistent with a physical lens cover or privacy shutter left closed.

What this cannot check

No web page — this one included — can see other browser tabs, other applications, or background system processes. That is a deliberate security boundary, not a limitation of this specific tool. If you need to know exactly which application currently holds your camera, that information only exists at the operating-system level: Windows' camera privacy settings and Task Manager, or macOS's camera indicator and Activity Monitor, both show this directly.

基准参考

真实浏览器错误代码

错误名称	诊断	修复
NotAllowedError（权限已授予）	操作系统级阻止	检查操作系统的摄像头隐私设置。
NotAllowedError（权限未授予）	浏览器权限被拒绝	点击地址栏中的摄像头图标。
NotFoundError	未找到设备	检查线缆、设备管理器，或操作系统级别的禁用设置。
NotReadableError	摄像头正在别处使用	关闭其他正在使用摄像头的应用/标签页。
OverconstrainedError	参数不匹配，并非被阻止	Not actually inaccessible — request different settings.

These are the real, standard error names getUserMedia reports — this tool reads yours directly rather than guessing.

分步说明

如何运行诊断

点击「运行诊断」——无需任何设置。
响应权限提示（如果出现）。
Read the three-step readout: permission state, stream attempt result, and a frame-content check for physical obstruction.
按照显示的具体指引操作，针对实际检测到的错误（如果有的话）。

常见问题

网站能否知道另一个应用是否在窥探我的摄像头？

No, and any tool that claims to is not being straight with you. Browser security is specifically designed so a web page cannot see other tabs, other applications, or background processes — that isolation is a core protection, not a gap. This tool reports what a page genuinely can see: its own permission state and stream errors, plus a check of whether the live image looks physically obstructed.

My camera light is off but an app says it's in use — what's happening?

On the large majority of modern webcams, the indicator LED is wired directly to the camera's power rail specifically so software cannot disable it while hiding sensor activity. If the light is genuinely off, the sensor is almost certainly not capturing. Check your OS's own camera-usage indicator or Task Manager / Activity Monitor for which process actually has it open.

NotReadableError 是什么意思？

The camera was found but the operating system would not hand it over to the browser — almost always because another application already has it open. Close other video apps and browser tabs using the camera and try again.

如何在 Windows 或 Mac 上检查哪个应用正在使用我的摄像头？

Windows 10 and 11 show a camera-in-use indicator in the system tray, and Settings → Privacy → Camera lists recent app access. macOS shows an orange/green indicator light plus, in recent versions, a dot in the menu bar you can click to see which app is using the camera or microphone.

为什么显示「权限已授予」，但摄像头仍然无法启动？

That specific contradiction — browser reports granted, stream still fails — is the clearest signature of an OS-level privacy block sitting behind an already-approved browser permission. It means something outside the browser, not the browser itself, is the actual blocker.