Skip motion threshold configuration (#22255)

* backend

* frontend

* i18n

* docs

* add test

* clean up

* clean up motion detection docs

* formatting

* make optional

frigate/config/camera/motion.py

@@ -24,10 +24,17 @@ class MotionConfig(FrigateBaseModel):
     lightning_threshold: float = Field(
         default=0.8,
         title="Lightning threshold",
-        description="Threshold to detect and ignore brief lighting spikes (lower is more sensitive, values between 0.3 and 1.0).",
+        description="Threshold to detect and ignore brief lighting spikes (lower is more sensitive, values between 0.3 and 1.0). This does not prevent motion detection entirely; it merely causes the detector to stop analyzing additional frames once the threshold is exceeded. Motion-based recordings are still created during these events.",
         ge=0.3,
         le=1.0,
     )
+    skip_motion_threshold: Optional[float] = Field(
+        default=None,
+        title="Skip motion threshold",
+        description="If set to a value between 0.0 and 1.0, and more than this fraction of the image changes in a single frame, the detector will return no motion boxes and immediately recalibrate. This can save CPU and reduce false positives during lightning, storms, etc., but may miss real events such as a PTZ camera auto‑tracking an object. The trade‑off is between dropping a few megabytes of recordings versus reviewing a couple short clips. Leave unset (None) to disable this feature.",
+        ge=0.0,
+        le=1.0,
+    )
     improve_contrast: bool = Field(
         default=True,
         title="Improve contrast",

frigate/motion/improved_motion.py

@@ -176,11 +176,32 @@ class ImprovedMotionDetector(MotionDetector):
             motion_boxes = []
             pct_motion = 0
 
+        # skip motion entirely if the scene change percentage exceeds configured
+        # threshold. this is useful to ignore lighting storms, IR mode switches,
+        # etc. rather than registering them as brief motion and then recalibrating.
+        # note: skipping means the frame is dropped and **no recording will be
+        # created**, which could hide a legitimate object if the camera is actively
+        # auto‑tracking. the alternative is to allow motion and accept a small
+        # recording that can be reviewed in the timeline. disabled by default (None).
+        if (
+            self.config.skip_motion_threshold is not None
+            and pct_motion > self.config.skip_motion_threshold
+        ):
+            # force a recalibration so we transition to the new background
+            self.calibrating = True
+            return []
+
         # once the motion is less than 5% and the number of contours is < 4, assume its calibrated
         if pct_motion < 0.05 and len(motion_boxes) <= 4:
             self.calibrating = False
 
-        # if calibrating or the motion contours are > 80% of the image area (lightning, ir, ptz) recalibrate
+        # if calibrating or the motion contours are > 80% of the image area
+        # (lightning, ir, ptz) recalibrate. the lightning threshold does **not**
+        # stop motion detection entirely; it simply halts additional processing for
+        # the current frame once the percentage crosses the threshold. this helps
+        # reduce false positive object detections and CPU usage during high‑motion
+        # events. recordings continue to be generated because users expect data
+        # while a PTZ camera is moving.
         if self.calibrating or pct_motion > self.config.lightning_threshold:
             self.calibrating = True
 

frigate/test/test_motion_detector.py

@@ -0,0 +1,91 @@
+import unittest
+
+import numpy as np
+
+from frigate.config.camera.motion import MotionConfig
+from frigate.motion.improved_motion import ImprovedMotionDetector
+
+
+class TestImprovedMotionDetector(unittest.TestCase):
+    def setUp(self):
+        # small frame for testing; actual frames are grayscale
+        self.frame_shape = (100, 100)  # height, width
+        self.config = MotionConfig()
+        # motion detector assumes a rasterized_mask attribute exists on config
+        # when update_mask() is called; add one manually by bypassing pydantic.
+        object.__setattr__(
+            self.config,
+            "rasterized_mask",
+            np.ones((self.frame_shape[0], self.frame_shape[1]), dtype=np.uint8),
+        )
+
+        # create minimal PTZ metrics stub to satisfy detector checks
+        class _Stub:
+            def __init__(self, value=False):
+                self.value = value
+
+            def is_set(self):
+                return bool(self.value)
+
+        class DummyPTZ:
+            def __init__(self):
+                self.autotracker_enabled = _Stub(False)
+                self.motor_stopped = _Stub(False)
+                self.stop_time = _Stub(0)
+
+        self.detector = ImprovedMotionDetector(
+            self.frame_shape, self.config, fps=30, ptz_metrics=DummyPTZ()
+        )
+
+        # establish a baseline frame (all zeros)
+        base_frame = np.zeros(
+            (self.frame_shape[0], self.frame_shape[1]), dtype=np.uint8
+        )
+        self.detector.detect(base_frame)
+
+    def _half_change_frame(self) -> np.ndarray:
+        """Produce a frame where roughly half of the pixels are different."""
+        frame = np.zeros((self.frame_shape[0], self.frame_shape[1]), dtype=np.uint8)
+        # flip the top half to white
+        frame[: self.frame_shape[0] // 2, :] = 255
+        return frame
+
+    def test_skip_motion_threshold_default(self):
+        """With the default (None) setting, motion should always be reported."""
+        frame = self._half_change_frame()
+        boxes = self.detector.detect(frame)
+        self.assertTrue(
+            boxes, "Expected motion boxes when skip threshold is unset (disabled)"
+        )
+
+    def test_skip_motion_threshold_applied(self):
+        """Setting a low skip threshold should prevent any boxes from being returned."""
+        # change the config and update the detector reference
+        self.config.skip_motion_threshold = 0.4
+        self.detector.config = self.config
+        self.detector.update_mask()
+
+        frame = self._half_change_frame()
+        boxes = self.detector.detect(frame)
+        self.assertEqual(
+            boxes,
+            [],
+            "Motion boxes should be empty when scene change exceeds skip threshold",
+        )
+
+    def test_skip_motion_threshold_does_not_affect_calibration(self):
+        """Even when skipping, the detector should go into calibrating state."""
+        self.config.skip_motion_threshold = 0.4
+        self.detector.config = self.config
+        self.detector.update_mask()
+
+        frame = self._half_change_frame()
+        _ = self.detector.detect(frame)
+        self.assertTrue(
+            self.detector.calibrating,
+            "Detector should be in calibrating state after skip event",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()