electron/docs/tutorial/testing-widevine-cdm.md

Testing Widevine CDM

In Electron you can use the Widevine CDM library in builds compiled with Widevine support.

Widevine Content Decryption Modules (CDMs) are how streaming services protect content using HTML5 video in web browsers without relying on an NPAPI plugin like Flash or Silverlight. Electron can register a Widevine CDM when the Electron binary is built with Widevine support and the application provides compatible CDM files.

Note

Widevine support in Electron is experimental.

Note on VMP

As of Electron v1.8.0 (Chrome v59), the below steps may only be some of the necessary steps to enable Widevine; any app on or after that version intending to use the Widevine CDM may need to be signed using a license obtained from Widevine itself.

Per Widevine:

Chrome 59 (and later) includes support for Verified Media Path (VMP). VMP provides a method to verify the authenticity of a device platform. For browser deployments, this will provide an additional signal to determine if a browser-based implementation is reliable and secure.

The proxy integration guide has been updated with information about VMP and how to issue licenses.

Widevine recommends our browser-based integrations (vendors and browser-based applications) add support for VMP.

Electron does not download, update, license, or sign Widevine CDM files for applications. Application developers are responsible for obtaining any required CDM files, licenses, and VMP signing support from Widevine or an authorized integration provider.

Using the library

When developing an unpackaged application, pass the path to the directory that contains manifest.json with the --widevine-cdm-path command line switch. Electron reads the CDM version from manifest.json when possible. If the manifest does not contain the version, pass the library's version with --widevine-cdm-version.

On Linux, these switches must be present on Electron's process command line for an unpackaged application. The zygote loads library CDMs before Electron runs the app's main script, so calling app.commandLine.appendSwitch from that script is too late for sandboxed renderers:

electron \
  --widevine-cdm-path=/path/to/WidevineCdm \
  --widevine-cdm-version=4.10.2891.0 \
  /path/to/app

The version switch is optional when manifest.json contains a valid version.

On Windows and macOS, an unpackaged application can append the switches from its main script before the ready event is emitted.

Example code for Windows and macOS:

const { app, BrowserWindow } = require('electron')

app.commandLine.appendSwitch('widevine-cdm-path', '/path/to/WidevineCdm')

// Optional when manifest.json contains a valid version.
app.commandLine.appendSwitch('widevine-cdm-version', '4.10.2891.0')

let win = null
app.whenReady().then(() => {
  win = new BrowserWindow()
  win.show()
})

Packaged applications ignore --widevine-cdm-path to prevent loading library code from an arbitrary command-line path. On all platforms, packaged applications must bundle the WidevineCdm directory beside the Electron executable.

Verifying Widevine CDM support

To verify whether Widevine is registered, you can use the Encrypted Media Extensions API:

const config = [
  {
    initDataTypes: ['cenc'],
    videoCapabilities: [
      {
        contentType: 'video/webm; codecs="vp8"'
      }
    ],
    audioCapabilities: [
      {
        contentType: 'audio/webm; codecs="opus"'
      }
    ]
  }
]

navigator
  .requestMediaKeySystemAccess('com.widevine.alpha', config)
  .then(() => {
    console.log('Widevine is available')
  })
  .catch((error) => {
    console.error('Widevine is unavailable:', error.name)
  })

This check only verifies key system availability. Successful protected playback also depends on the CDM package, media codec support, the license server, and any VMP or application-signing requirements imposed by the content provider.