Add a camera feed demo in misc

[shiena]

This is a demo project for camera feed and camera server.

Supported Platforms

• Linux
• macOS
• Android (4.5 or later)

Limitations

Pull requests have been proposed for Windows, iOS and Web.

• Add CameraFeed support for Windows godot#105476
• Add CameraFeed support for Windows godot#108538
• Add CameraFeed support for iOS godot#106305
• Add CameraFeed support for Web godot#106784

macOS and iOS are incomplete due to bugs.

• Support CameraFeed format on macOS godot#106777
• [macOS] Fix missing frame_changed signal to CameraFeed godot#104809

Android: Handle YUV_420_888 strides correctly in CameraFeed

• Android: Handle YUV_420_888 strides correctly in CameraFeed godot#110720

Support CameraServer.feeds_updated signal.

• Add CameraServer feeds_updated signal, and document async behavior godot#108165

Defer format_changed and frame_changed signal for all camera feeds.

• Defer format_changed and frame_changed signal for all camera feeds godot#109594

Preview

[Calinou]

Note that the demo requires 4.5 (even on unsupported platforms), as it references the monitoring_feeds property which doesn't exist on 4.4.1. This is not essential to fix to merge (it's fine for this demo to be 4.5+), but I thought I'd mention nonetheless.

Some feedback:

• The demo should be switched to the Compatibility rendering method if it doesn't use features exclusive to Forward+/Mobile.
• The demo's folder should be renamed from camerafeed to camera_feed.
• application/run/low_processor_mode should be enabled in the Project Settings to reduce CPU/GPU utilization when idle.

[shiena]

@Calinou
Updated based on review feedback:

• Add require 4.5
• Switch to the Compatibility rendering
• Rename from camerafeed to camera_feed
• Enable application/run/low_processor_mode

[Calinou]

The demo should use a lower window size on desktop platforms. Otherwise, on a 1080p display, it'll look like this when run from the editor with game window embedding enabled:

You can do this by changing Window Width Override and Window Height Override to 480 and 854 respectively. This will allow it to fit on a 1080p display. (The setting is ignored on mobile platforms.)

[shiena]

• Changed Window Width Override and Window Height Override

[shiena]

@AThousandShips Address review comments.

[Calinou]

I've tested the demo on macOS with 4.5.stable and I noticed that while the camera name appears, I can't choose any format:

After clicking Reload, I see a permission prompt. When I accept it, the LED next to the webcam lights up, but I still don't see anything. I don't see any errors in the terminal. This occurs regardless of how I'm running Godot (it's the official 4.5 .app bundle, I've tried running it from a terminal but also from Spotlight). Maybe I'm missing an entitlement? cc @bruvzg

[shiena]

@Calinou
Format is currently not supported. You will be able to select from a list once godotengine/godot#106777 is merged.

[bruvzg]

Current entitlements should be fine, but if you are using multiple bundles with the same id at the same (and all versions of Godot have the same id) permission can sometimes stop working. Removing it from the allowed app list in the system settings (minus button) completly and restarting the app should fix it.