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/track/norfair_tracker.py

@@ -12,10 +12,10 @@ from norfair import (
 )
 from norfair.drawing.drawer import Drawer
 
+from frigate.camera import PTZMetrics
 from frigate.config import CameraConfig
 from frigate.ptz.autotrack import PtzMotionEstimator
 from frigate.track import ObjectTracker
-from frigate.types import PTZMetricsTypes
 from frigate.util.image import intersection_over_union
 from frigate.util.object import average_boxes, median_of_boxes
 
@@ -75,7 +75,7 @@ class NorfairTracker(ObjectTracker):
     def __init__(
         self,
         config: CameraConfig,
-        ptz_metrics: PTZMetricsTypes,
+        ptz_metrics: PTZMetrics,
     ):
         self.tracked_objects = {}
         self.untracked_object_boxes: list[list[int]] = []
@@ -85,7 +85,6 @@ class NorfairTracker(ObjectTracker):
         self.camera_config = config
         self.detect_config = config.detect
         self.ptz_metrics = ptz_metrics
-        self.ptz_autotracker_enabled = ptz_metrics["ptz_autotracker_enabled"]
         self.ptz_motion_estimator = {}
         self.camera_name = config.name
         self.track_id_map = {}
@@ -104,7 +103,7 @@ class NorfairTracker(ObjectTracker):
             #       the different tracker per object class
             filter_factory=OptimizedKalmanFilterFactory(R=3.4),
         )
-        if self.ptz_autotracker_enabled.value:
+        if self.ptz_metrics.autotracker_enabled.value:
             self.ptz_motion_estimator = PtzMotionEstimator(
                 self.camera_config, self.ptz_metrics
             )
@@ -315,7 +314,7 @@ class NorfairTracker(ObjectTracker):
 
         coord_transformations = None
 
-        if self.ptz_autotracker_enabled.value:
+        if self.ptz_metrics.autotracker_enabled.value:
             # we must have been enabled by mqtt, so set up the estimator
             if not self.ptz_motion_estimator:
                 self.ptz_motion_estimator = PtzMotionEstimator(