add cpu fallback detector

frigate/config.py

@@ -1287,6 +1287,13 @@ class FrigateConfig(FrigateBaseModel):
         config.model.check_and_load_plus_model(plus_api)
 
         for key, detector in config.detectors.items():
+            config.detectors[key] = self.generate_detector_config(
+                config, detector, plus_api
+            )
+
+        return config
+
+    def generate_detector_config(self, config: FrigateConfig, detector, plus_api):
         detector_config: DetectorConfig = parse_obj_as(DetectorConfig, detector)
         if detector_config.model is None:
             detector_config.model = config.model
@@ -1321,9 +1328,17 @@ class FrigateConfig(FrigateBaseModel):
             plus_api, detector_config.type
         )
         detector_config.model.compute_model_hash()
-            config.detectors[key] = detector_config
 
-        return config
+        if detector_config.type != "cpu":
+            fallback_config = config.copy(deep=True)
+            fallback_config.model = ModelConfig()
+            detector_config.fallback_config = self.generate_detector_config(
+                fallback_config,
+                parse_obj_as(DetectorConfig, DEFAULT_DETECTORS["cpu"]),
+                plus_api,
+            )
+
+        return detector_config
 
     @validator("cameras")
     def ensure_zones_and_cameras_have_different_names(cls, v: Dict[str, CameraConfig]):

frigate/object_detection.py

@@ -81,6 +81,7 @@ def run_detector(
     out_events: dict[str, mp.Event],
     avg_speed,
     start,
+    using_fallback_detector,
     detector_config,
 ):
     threading.current_thread().name = f"detector:{name}"
@@ -99,7 +100,14 @@ def run_detector(
     signal.signal(signal.SIGINT, receiveSignal)
 
     frame_manager = SharedMemoryFrameManager()
+    try:
         object_detector = LocalObjectDetector(detector_config=detector_config)
+    except Exception as ex:
+        logger.error(f"Got exception when initializing detector: {ex}, falling back to CPU detector")
+
+        object_detector = LocalObjectDetector(detector_config=detector_config.fallback_config)
+        using_fallback_detector.value = 1
+        
 
     outputs = {}
     for name in out_events.keys():
@@ -146,6 +154,7 @@ class ObjectDetectProcess:
         self.detection_queue = detection_queue
         self.avg_inference_speed = mp.Value("d", 0.01)
         self.detection_start = mp.Value("d", 0.0)
+        self.using_fallback_detector = mp.Value("i", 0)
         self.detect_process = None
         self.detector_config = detector_config
         self.start_or_restart()
@@ -176,6 +185,7 @@ class ObjectDetectProcess:
                 self.out_events,
                 self.avg_inference_speed,
                 self.detection_start,
+                self.using_fallback_detector,
                 self.detector_config,
             ),
         )

frigate/stats.py

@@ -284,6 +284,7 @@ def stats_snapshot(
             # issue https://github.com/python/typeshed/issues/8799
             # from mypy 0.981 onwards
             "pid": pid,
+            "using_fallback_detector": bool(detector.using_fallback_detector.value),
         }
     stats["detection_fps"] = round(total_detection_fps, 2)
 

web/src/routes/System.jsx

@@ -232,7 +232,7 @@ export default function System() {
           <div data-testid="detectors" className="grid grid-cols-1 3xl:grid-cols-3 md:grid-cols-2 gap-4">
             {detectorNames.map((detector) => (
               <div key={detector} className="dark:bg-gray-800 shadow-md hover:shadow-lg rounded-lg transition-shadow">
-                <div className="text-lg flex justify-between p-4">{detector}</div>
+                <div className="text-lg flex justify-between p-4" style={{ color: detectors[detector]['using_fallback_detector'] ? "red" : null}}>{detector}{detectors[detector]['using_fallback_detector'] ? " - CPU FALLBACK MODE" : ""}</div>
                 <div className="p-2">
                   <Table className="w-full">
                     <Thead>