Sanitize floats for estimated speed and angle

Users can configure speed zones in such a way that velocity estimates from Norfair cause a value of inf to be stored as an estimated speed. FastAPI doesn't serialize inf as a float, so trying to return this value would result in an API error. Sanitizing the value before storing should correct this.

frigate/track/tracked_object.py

@@ -18,6 +18,7 @@ from frigate.config import (
 )
 from frigate.const import CLIPS_DIR, THUMB_DIR
 from frigate.review.types import SeverityEnum
+from frigate.util.builtin import sanitize_float
 from frigate.util.image import (
     area,
     calculate_region,
@@ -202,6 +203,11 @@ class TrackedObject:
                             )
                         )
 
+                        # users can configure speed zones incorrectly, so sanitize speed_magnitude
+                        # and velocity_angle in case the values come back as inf or NaN
+                        speed_magnitude = sanitize_float(speed_magnitude)
+                        self.velocity_angle = sanitize_float(self.velocity_angle)
+
                         if self.ui_config.unit_system == "metric":
                             self.current_estimated_speed = (
                                 speed_magnitude * 3.6

frigate/util/builtin.py

@@ -4,6 +4,7 @@ import ast
 import copy
 import datetime
 import logging
+import math
 import multiprocessing as mp
 import queue
 import re
@@ -399,3 +400,10 @@ def serialize(
 def deserialize(bytes_data: bytes) -> list[float]:
     """Deserializes a compact "raw bytes" format into a list of floats"""
     return list(struct.unpack("%sf" % (len(bytes_data) // 4), bytes_data))
+
+
+def sanitize_float(value):
+    """Replace NaN or inf with 0.0."""
+    if isinstance(value, (int, float)) and not math.isfinite(value):
+        return 0.0
+    return value