ultralytics 8.0.71 updates and fixes (#1907)

Co-authored-by: Laughing <61612323+Laughing-q@users.noreply.github.com>
Co-authored-by: Pavel Bugneac <50273042+pavelbugneac@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

ultralytics/tracker/track.py

@@ -1,5 +1,7 @@
 # Ultralytics YOLO 🚀, GPL-3.0 license
 
+from functools import partial
+
 import torch
 
 from ultralytics.yolo.utils import IterableSimpleNamespace, yaml_load
@@ -10,7 +12,19 @@ from .trackers import BOTSORT, BYTETracker
 TRACKER_MAP = {'bytetrack': BYTETracker, 'botsort': BOTSORT}
 
 
-def on_predict_start(predictor):
+def on_predict_start(predictor, persist=False):
+    """
+    Initialize trackers for object tracking during prediction.
+
+    Args:
+        predictor (object): The predictor object to initialize trackers for.
+        persist (bool, optional): Whether to persist the trackers if they already exist. Defaults to False.
+
+    Raises:
+        AssertionError: If the tracker_type is not 'bytetrack' or 'botsort'.
+    """
+    if hasattr(predictor, 'trackers') and persist:
+        return
     tracker = check_yaml(predictor.args.tracker)
     cfg = IterableSimpleNamespace(**yaml_load(tracker))
     assert cfg.tracker_type in ['bytetrack', 'botsort'], \
@@ -38,6 +52,14 @@ def on_predict_postprocess_end(predictor):
         predictor.results[i].update(boxes=torch.as_tensor(tracks[:, :-1]))
 
 
-def register_tracker(model):
-    model.add_callback('on_predict_start', on_predict_start)
+def register_tracker(model, persist):
+    """
+    Register tracking callbacks to the model for object tracking during prediction.
+
+    Args:
+        model (object): The model object to register tracking callbacks for.
+        persist (bool): Whether to persist the trackers if they already exist.
+
+    """
+    model.add_callback('on_predict_start', partial(on_predict_start, persist=persist))
     model.add_callback('on_predict_postprocess_end', on_predict_postprocess_end)

ultralytics/tracker/trackers/byte_tracker.py

@@ -277,12 +277,13 @@ class BYTETracker:
         self.lost_stracks = self.sub_stracks(self.lost_stracks, self.tracked_stracks)
         self.lost_stracks.extend(lost_stracks)
         self.lost_stracks = self.sub_stracks(self.lost_stracks, self.removed_stracks)
-        self.removed_stracks.extend(removed_stracks)
         self.tracked_stracks, self.lost_stracks = self.remove_duplicate_stracks(self.tracked_stracks, self.lost_stracks)
-        output = [
-            track.tlbr.tolist() + [track.track_id, track.score, track.cls, track.idx] for track in self.tracked_stracks
-            if track.is_activated]
-        return np.asarray(output, dtype=np.float32)
+        self.removed_stracks.extend(removed_stracks)
+        if len(self.removed_stracks) > 1000:
+            self.removed_stracks = self.removed_stracks[-999:]  # clip remove stracks to 1000 maximum
+        return np.asarray(
+            [x.tlbr.tolist() + [x.track_id, x.score, x.cls, x.idx] for x in self.tracked_stracks if x.is_activated],
+            dtype=np.float32)
 
     def get_kalmanfilter(self):
         return KalmanFilterXYAH()
@@ -319,12 +320,16 @@ class BYTETracker:
 
     @staticmethod
     def sub_stracks(tlista, tlistb):
+        """ DEPRECATED CODE in https://github.com/ultralytics/ultralytics/pull/1890/
         stracks = {t.track_id: t for t in tlista}
         for t in tlistb:
             tid = t.track_id
             if stracks.get(tid, 0):
                 del stracks[tid]
         return list(stracks.values())
+        """
+        track_ids_b = {t.track_id for t in tlistb}
+        return [t for t in tlista if t.track_id not in track_ids_b]
 
     @staticmethod
     def remove_duplicate_stracks(stracksa, stracksb):