Custom classes for Process and Metrics (#13950)

* Subclass Process for audio_process

* Introduce custom mp.Process subclass

In preparation to switch the multiprocessing startup method away from
"fork", we cannot rely on os.fork cloning the log state at fork time.
Instead, we have to set up logging before we run the business logic of
each process.

* Make camera_metrics into a class

* Make ptz_metrics into a class

* Fixed PtzMotionEstimator.ptz_metrics type annotation

* Removed pointless variables

* Do not start audio processor when no audio cameras are configured

frigate/types.py

@@ -1,42 +1,11 @@
-from multiprocessing import Queue
-from multiprocessing.context import Process
-from multiprocessing.sharedctypes import Synchronized
-from multiprocessing.synchronize import Event
-from typing import Optional, TypedDict
+from typing import TypedDict
 
+from frigate.camera import CameraMetrics
 from frigate.object_detection import ObjectDetectProcess
 
 
-class CameraMetricsTypes(TypedDict):
-    camera_fps: Synchronized
-    capture_process: Optional[Process]
-    detection_fps: Synchronized
-    detection_frame: Synchronized
-    ffmpeg_pid: Synchronized
-    frame_queue: Queue
-    process: Optional[Process]
-    process_fps: Synchronized
-    read_start: Synchronized
-    skipped_fps: Synchronized
-    audio_rms: Synchronized
-    audio_dBFS: Synchronized
-
-
-class PTZMetricsTypes(TypedDict):
-    ptz_autotracker_enabled: Synchronized
-    ptz_tracking_active: Event
-    ptz_motor_stopped: Event
-    ptz_reset: Event
-    ptz_start_time: Synchronized
-    ptz_stop_time: Synchronized
-    ptz_frame_time: Synchronized
-    ptz_zoom_level: Synchronized
-    ptz_max_zoom: Synchronized
-    ptz_min_zoom: Synchronized
-
-
 class StatsTrackingTypes(TypedDict):
-    camera_metrics: dict[str, CameraMetricsTypes]
+    camera_metrics: dict[str, CameraMetrics]
     detectors: dict[str, ObjectDetectProcess]
     started: int
     latest_frigate_version: str