feat: live count worker, tracking, and page updates

backend/live_count.py

@@ -43,7 +43,8 @@ class Session:
                  dedup_radius: float, margin: int, imgsz: int,
                  entry_travel_min: float, handoff_radius: float,
                  unload_confirm_frames: int, min_area_scale: float,
-                 spatial_dedup: bool, whep_url: str = ""):
+                 spatial_dedup: bool, whep_url: str = "",
+                 count_classes: tuple = ("sack",)):
         self.source = source
         # When the browser watches the camera over WebRTC it never asks for the
         # MJPEG, so encoding a JPEG per frame would be pure waste (REQ-177).
@@ -61,6 +62,7 @@ class Session:
         self.unload_confirm_frames = unload_confirm_frames
         self.min_area_scale = min_area_scale
         self.spatial_dedup = spatial_dedup
+        self.count_classes = tuple(count_classes)
 
         self.started_at = time.time()
         self.error = ""
@@ -167,7 +169,8 @@ class Session:
             # segfault without it (same reason predict.py does this).
             model(np.zeros((720, 1280, 3), dtype=np.uint8), imgsz=self.imgsz, verbose=False)
 
-            tracker = ByteTrackTracker(model, self.conf)
+            tracker = ByteTrackTracker(model, self.conf,
+                                         class_filter=tuple(self.count_classes))
             stabilizer = BboxStabilizer(ema_alpha=0.35, max_hold_frames=10,
                                         max_height_ratio=1.5, min_height_ratio=0.70)
             counter = LineCrossCounter(
@@ -200,7 +203,8 @@ class Session:
                     break
 
                 frame = cv2.resize(frame, (1280, 720))
-                detections = [d for d in tracker.update(frame, []) if d.class_name == "sack"]
+                # The tracker only emits count_classes, so no post-filter is needed.
+                detections = tracker.update(frame, [])
                 stable = stabilizer.update(detections)
                 inside, outside = [], []
                 small = 0
@@ -338,7 +342,7 @@ def start(source: str, model_path: str, line_y: int, line_x_start: int, line_x_e
           imgsz: int = 640, entry_travel_min: float = 60.0,
           handoff_radius: float = 100.0, unload_confirm_frames: int = 3,
           min_area_scale: float = 1.0, spatial_dedup: bool = False,
-          whep: str = "") -> dict:
+          whep: str = "", count_classes: tuple = ("sack",)) -> dict:
     global _session
     with _guard:
         if _session is not None and _session.status()["running"]:
@@ -350,7 +354,7 @@ def start(source: str, model_path: str, line_y: int, line_x_start: int, line_x_e
         _session = Session(source, model_path, line_y, line_x_start, line_x_end,
                            conf, dedup_radius, margin, imgsz, entry_travel_min,
                            handoff_radius, unload_confirm_frames, min_area_scale,
-                           spatial_dedup, whep)
+                           spatial_dedup, whep, count_classes)
         _session.start()
     time.sleep(0.4)          # let an immediate failure surface in the response
     return _session.status()