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/__main__.py

@@ -1,6 +1,5 @@
 import argparse
 import faulthandler
-import logging
 import signal
 import sys
 import threading
@@ -9,29 +8,20 @@ from pydantic import ValidationError
 
 from frigate.app import FrigateApp
 from frigate.config import FrigateConfig
-from frigate.log import log_thread
+from frigate.log import setup_logging
 
 
 def main() -> None:
     faulthandler.enable()
 
-    # Clear all existing handlers.
-    logging.basicConfig(
-        level=logging.INFO,
-        handlers=[],
-        force=True,
-    )
+    # Setup the logging thread
+    setup_logging()
 
     threading.current_thread().name = "frigate"
 
     # Make sure we exit cleanly on SIGTERM.
     signal.signal(signal.SIGTERM, lambda sig, frame: sys.exit())
 
-    run()
-
-
-@log_thread()
-def run() -> None:
     # Parse the cli arguments.
     parser = argparse.ArgumentParser(
         prog="Frigate",