mizt / coremediaio-dal-minimal-example

Intended to be the most minimalistic example of a macOS CoreMediaIO DAL plugin.

CoreMediaIO Device Abstraction Layer (DAL) Minimal Example

This example project is intended to present the simplest possible implementation of a CoreMediaIO DAL plugin for creating a virtual webcam on macOS. Apple provides sample code (also modernized by @lvsti) but it's extremely painful to read and modify.

The goal is for this plugin to serve static frames as a virtual webcam to host software (QuickTime, OBS, Chrome, etc)

Other Examples

Other projects that have implemented a DAL plugin are probably going to give the most insight as to what is missing here.

These projects are direct copies of Apple's own sample code.

• lvsti/CoreMediaIO-DAL-Example
• johnboiles/obs-mac-virtualcam - A fork of @lvsti's repo but adapted to work with OBS.

This project seems significantly different than the Apple sample code in its implementation.

• webcamoid/webcamoid

Other examples would be helpful!

Developing

To try this out:

• Build it in Xcode
• Find CMIOMinimalSample.plugin in Xcode's 'Products' folder
• Right click CMIOMinimalSample.plugin and choose 'Show in Finder'
• Copy the plugin bundle to /Library/CoreMediaIO/Plug-Ins/DAL/
• Open QuickTime
• Watch the logs in Console.app for any logs prefixed with CMIOMS

You may also need to change the codesigning to use your own personal developer identity.

Also take a look at Cameo by @lvsti. It allows you to inspect DAL plugins and see all their properties at a glance. It might be helpful to take a known-working plugin (perhaps johnboiles/obs-mac-virtualcam or Snap Camera and try to figure out the differences between those plugins and this plugin.

License

This software is licensed as MIT. Do what you want with it! But please, if you find ways to improve this software, or you find bugs, please open a Pull Request so others can benefit from it!