A camera is a device used to capture images and videos, widely used in surveillance, video conferencing, photography, and more. Modern cameras typically feature high resolution, autofocus, low-light enhancement, and other advanced functionalities.
The working principle of a camera involves focusing light through a lens onto an image sensor. The sensor converts the light signal into an electrical signal, which is then processed by a chip to produce a digital image.
When selecting a camera, factors such as resolution, frame rate, field of view, and low-light performance should be considered. High-resolution cameras capture clearer images, while high-frame-rate cameras are suitable for capturing fast-moving objects.
Modern browsers access the user's camera and microphone through WebRTC technology. WebRTC is an open-source project that enables real-time communication, allowing browsers to directly capture audio and video streams.
When the user clicks the "Start Test" button, the browser requests permission to access the camera. If the user grants permission, the browser accesses the camera using the getUserMedia API and displays the video stream on the page.
Permission Request: The browser displays a permission request dialog, and the user must explicitly allow access to the camera. If the user denies the request, the browser will be unable to access the camera and will throw an error.
How It Works: The video stream captured by the camera is displayed in real-time on the webpage using the <video> tag. The video stream can be controlled via JavaScript, such as starting, stopping, taking photos, or recording.
Security: To ensure user privacy, browsers only allow camera access over HTTPS or in local environments. If the website does not use HTTPS, camera access will be blocked.