Browser webcam hello world

Just below this paragraph, you can see yourself! In this post I show how webpages can access the webcam, then stream it to a <video> element.

Here’s the code that achieves this:

<!-- First, a video element to stream the webcam to ... -->
<video id="webcam" width="400"></video>
// ... then some JavaScript to access the webcam stream 
// and attach it to the video element.
const vidEl = document.getElementById("webcam");
navigator.mediaDevices.getUserMedia({ video: { facingMode: "user" } })
  .then(stream => {
    vidEl.srcObject = stream;
    vidEl.play();
  })
  .catch((err) => console.log("error getting webcam", err));

When this page loaded, it prompted you for permission to access your webcam. This happened when the page called navigator.mediaDevices.getUserMedia(...), which returns a Promise<MediaStream>. When you respond to the permission request, the promise resolves (or rejects, if you deny permission).

The <video> element, as an HTMLMediaElement, has a srcObject property which can be any MediaStream. By assigning the webcam stream to the <video> element’s input, we display the webcam.

Finally, to start using the source, you must call .play() on the <video> element.

I just released Vidrio, a free app for macOS and Windows to make your screen-sharing awesomely holographic. Vidrio shows your webcam video on your screen, just like a mirror. Then you just share or record your screen with Zoom, QuickTime, or any other app. Vidrio makes your presentations effortlessly engaging, showing your gestures, gazes, and expressions. #1 on Product Hunt. Available for macOS and Windows.

With Vidrio

With generic competitor

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Tagged #programming. All content copyright James Fisher 2019. This post is not associated with my employer. Found an error? Edit this page.