From 75c85709132c9ecffbbe9d0db8b82379f8a2fda1 Mon Sep 17 00:00:00 2001
From: Blake Blackshear <blakeb@blakeshome.com>
Date: Sat, 30 Oct 2021 14:01:31 -0500
Subject: [PATCH] reduce detection rate for stationary objects

---
 frigate/objects.py | 10 +++++++++-
 frigate/video.py   | 29 ++++++++++++++++++++++++++---
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/frigate/objects.py b/frigate/objects.py
index 4da7f12d4..dc2b1b55e 100644
--- a/frigate/objects.py
+++ b/frigate/objects.py
@@ -13,7 +13,7 @@ import numpy as np
 from scipy.spatial import distance as dist
 
 from frigate.config import DetectConfig
-from frigate.util import draw_box_with_label
+from frigate.util import intersection_over_union
 
 
 class ObjectTracker:
@@ -27,6 +27,7 @@ class ObjectTracker:
         id = f"{obj['frame_time']}-{rand_id}"
         obj["id"] = id
         obj["start_time"] = obj["frame_time"]
+        obj["motionless_count"] = 0
         self.tracked_objects[id] = obj
         self.disappeared[id] = 0
 
@@ -36,6 +37,13 @@ class ObjectTracker:
 
     def update(self, id, new_obj):
         self.disappeared[id] = 0
+        if (
+            intersection_over_union(self.tracked_objects[id]["box"], new_obj["box"])
+            > 0.9
+        ):
+            self.tracked_objects[id]["motionless_count"] += 1
+        else:
+            self.tracked_objects[id]["motionless_count"] = 0
         self.tracked_objects[id].update(new_obj)
 
     def match_and_update(self, frame_time, new_objects):
diff --git a/frigate/video.py b/frigate/video.py
index 2e46bc590..0d6bf201e 100755
--- a/frigate/video.py
+++ b/frigate/video.py
@@ -498,9 +498,21 @@ def process_frames(
         # look for motion
         motion_boxes = motion_detector.detect(frame)
 
-        # only get the tracked object boxes that intersect with motion
+        # get stationary object ids
+        # check every 10th frame for stationary objects
+        stationary_object_ids = [
+            obj["id"]
+            for obj in object_tracker.tracked_objects.values()
+            if obj["motionless_count"] >= 10
+            and obj["motionless_count"] % 10 != 0
+            and object_tracker.disappeared[obj["id"]] == 0
+        ]
+
+        # get tracked object boxes that aren't stationary
         tracked_object_boxes = [
-            obj["box"] for obj in object_tracker.tracked_objects.values()
+            obj["box"]
+            for obj in object_tracker.tracked_objects.values()
+            if not obj["id"] in stationary_object_ids
         ]
 
         # combine motion boxes with known locations of existing objects
@@ -513,7 +525,18 @@ def process_frames(
         ]
 
         # resize regions and detect
-        detections = []
+        # seed with stationary objects
+        detections = [
+            (
+                obj["label"],
+                obj["score"],
+                obj["box"],
+                obj["area"],
+                obj["region"],
+            )
+            for obj in object_tracker.tracked_objects.values()
+            if obj["id"] in stationary_object_ids
+        ]
         for region in regions:
             detections.extend(
                 detect(