homebridge-camera-ffmpeg by Sunoo and its contributors. It has worked reliably for years, and it is the reason anyone can put an RTSP camera in HomeKit at all. This plugin differs in the shape of its configuration and in how it handles credentials, snapshots and failure, not in the idea, which is theirs.
ffmpeg does the actual work, and ffmpeg-for-homebridge makes a suitable static build available without asking every user to compile one.
hap-nodejs implements the HomeKit Accessory Protocol, including the camera controller this plugin plugs into.
OpenBridge provides the bridge, the device model and the plugin host.
Sponsorship
MIT licensed and free. If it is useful, sponsorship helps: camera integrations need hardware to test against.