LPR improvements (#17289)

* config options

* processing in maintainer

* detect and process dedicated lpr plates

* create camera type, add manual event and save snapshot

* use const

* ensure lpr events are always detections, typing fixes

* docs

* docs tweaks

* add preprocessing and penalization for low confidence chars

frigate/config/camera/camera.py

@@ -1,4 +1,5 @@
 import os
+from enum import Enum
 from typing import Optional
 
 from pydantic import Field, PrivateAttr
@@ -42,6 +43,11 @@ from .zone import ZoneConfig
 __all__ = ["CameraConfig"]
 
 
+class CameraTypeEnum(str, Enum):
+    generic = "generic"
+    lpr = "lpr"
+
+
 class CameraConfig(FrigateBaseModel):
     name: Optional[str] = Field(None, title="Camera name.", pattern=REGEX_CAMERA_NAME)
     enabled: bool = Field(default=True, title="Enable camera.")
@@ -102,6 +108,7 @@ class CameraConfig(FrigateBaseModel):
     onvif: OnvifConfig = Field(
         default_factory=OnvifConfig, title="Camera Onvif Configuration."
     )
+    type: CameraTypeEnum = Field(default=CameraTypeEnum.generic, title="Camera Type")
     ui: CameraUiConfig = Field(
         default_factory=CameraUiConfig, title="Camera UI Modifications."
     )

frigate/config/classification.py

@@ -127,6 +127,11 @@ class LicensePlateRecognitionConfig(FrigateBaseModel):
 
 class CameraLicensePlateRecognitionConfig(FrigateBaseModel):
     enabled: bool = Field(default=False, title="Enable license plate recognition.")
+    expire_time: int = Field(
+        default=3,
+        title="Expire plates not seen after number of seconds (for dedicated LPR cameras only).",
+        gt=0,
+    )
     min_area: int = Field(
         default=1000,
         title="Minimum area of license plate to begin running recognition.",