There are three major kinds of CMIO Camera Extensions: software camera, creative camera, and output device. OffcutsCam and TechnicalDifficulties are examples of software cameras (all content generated inside the extension), ArtFilm is an example of a creative camera (modifies a feed originating from another camera) and this is an example of an output device.
In an output device, the camera extension shows software or creative camera content (in this case, the same ascending and descending software white line content as OffcutsCam), but the extension has an input stream it can send to a camera output, so the CMIO Camera Extension can optionally output video that is streaming into it from the container app (in this case, the AVCaptureSession feed from the Continuity Camera or .userPreferred camera, i.e. a live camera feed which is not part of the CMIO Camera Extension).
I wanted to thank Laurent Denoue again for providing a reference example of this type of CMIOExtensionStreamSource and how it can be addressed by the app.
If you want to give it a try, it is necessary to change all references to my team ID and organization ID to yours (this occurs in a few places) or it will not be possible for you to codesign and install. This can only be run on a Ventura beta or later (at the time of this writing, there was no general release of Ventura yet), and if you want to use the Continuity Camera, you also need iOS 16 on your phone.
This is part 3.5 😅 of my three-part series on CMIO Camera Extensions on The Offcuts