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desktopCapturer

Access information about media sources that can be used to capture audio and video from the desktop using the navigator.mediaDevices.getUserMedia API.

Process: Main

The following example shows how to capture video from a desktop window whose title is Electron:

// main.js
const { app, BrowserWindow, desktopCapturer, session } = require('electron')

app.whenReady().then(() => {
  const mainWindow = new BrowserWindow()

  session.defaultSession.setDisplayMediaRequestHandler((request, callback) => {
    // If we should use the system picker
    // Note: this is currently experimental
    if (desktopCapturer.isDisplayMediaSystemPickerAvailable()) {
      callback({ video: desktopCapturer.systemPickerVideoSource })
      return
    }
    desktopCapturer.getSources({ types: ['screen'] }).then((sources) => {
      // Grant access to the first screen found.
      callback({ video: sources[0], audio: 'loopback' })
    })
  })

  mainWindow.loadFile('index.html')
})

// renderer.js
const startButton = document.getElementById('startButton')
const stopButton = document.getElementById('stopButton')
const video = document.querySelector('video')

startButton.addEventListener('click', () => {
  navigator.mediaDevices.getDisplayMedia({
    audio: true,
    video: {
      width: 320,
      height: 240,
      frameRate: 30
    }
  }).then(stream => {
    video.srcObject = stream
    video.onloadedmetadata = (e) => video.play()
  }).catch(e => console.log(e))
})

stopButton.addEventListener('click', () => {
  video.pause()
})

<!-- index.html -->
<html>
<meta http-equiv="content-security-policy" content="script-src 'self' 'unsafe-inline'" />
  <body>
    <button id="startButton" class="button">Start</button>
    <button id="stopButton" class="button">Stop</button>
    <video width="320" height="240" autoplay></video>
    <script src="renderer.js"></script>
  </body>
</html>

See navigator.mediaDevices.getDisplayMedia for more information.

Note: navigator.mediaDevices.getDisplayMedia does not permit the use of deviceId for selection of a source - see specification.

Methods

The desktopCapturer module has the following methods:

`desktopCapturer.getSources(options)`

options Object
- types string[] - An array of strings that lists the types of desktop sources to be captured, available types can be screen and window.
- thumbnailSize Size (optional) - The size that the media source thumbnail should be scaled to. Default is 150 x 150. Set width or height to 0 when you do not need the thumbnails. This will save the processing time required for capturing the content of each window and screen.
- fetchWindowIcons boolean (optional) - Set to true to enable fetching window icons. The default value is false. When false the appIcon property of the sources return null. Same if a source has the type screen.

Returns Promise<DesktopCapturerSource[]> - Resolves with an array of DesktopCapturerSource objects, each DesktopCapturerSource represents a screen or an individual window that can be captured.

Note Capturing the screen contents requires user consent on macOS 10.15 Catalina or higher, which can detected by systemPreferences.getMediaAccessStatus.

`desktopCapturer.isDisplayMediaSystemPickerAvailable()` Experimental

Returns Boolean, whether or not requesting desktop content via the system picker is supported on this platform.

Currently this will only return true on macOS 14.4 and higher. When true you should respect this value and use systemPickerVideoSource as otherwise the OS may present scary warning dialogs to your users.

Properties

`desktopCapturer.systemPickerVideoSource` Experimental Readonly

A DesktopCapturerSource property that should be used in conjunction with session.setDisplayMediaRequestHandler to use the system picker instead of providing a specific video source from getSources.

Caveats

navigator.mediaDevices.getUserMedia does not work on macOS for audio capture due to a fundamental limitation whereby apps that want to access the system's audio require a signed kernel extension. Chromium, and by extension Electron, does not provide this.

It is possible to circumvent this limitation by capturing system audio with another macOS app like Soundflower and passing it through a virtual audio input device. This virtual device can then be queried with navigator.mediaDevices.getUserMedia.

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