Enabling audio from the plugin settings breaks live streaming from Home app
I've successfully managed to pull an rtsp stream from my VMS into homebridge and the Home app using this plugin! 

When I toggle audio on and restart Homebridge using the "Enable Audio" option in the camera ffmpeg plugin settings, live video stops working in the Home app, and I see an error in the Homebridge console from ffmpeg.

Disabling audio lets me stream live video from the Home app again.

The Home app still gets new thumbnails from the camera every ~10 seconds regardless of the audio being enabled or not, probably because that doesn't use audio. 

The error printed in the homebridge console is `FFmpeg exited with code: 1 and signal: null (Error)`

Happy to provide any additional information or logs! Thank you