diff --git a/src/veyoff/capture.py b/src/veyoff/capture.py
index 00f4564..87275aa 100644
--- a/src/veyoff/capture.py
+++ b/src/veyoff/capture.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import time
 from dataclasses import dataclass
 from typing import Optional
 
@@ -13,7 +12,6 @@
 @dataclass
 class CachedFrame:
     frame: Image.Image
-    timestamp: float
 
 
 class ScreenCapture:
@@ -38,7 +36,7 @@ def capture_screen(self) -> Image.Image:
         return frame
 
     def save_frame_to_buffer(self, frame: Image.Image) -> None:
-        self._cached_frame = CachedFrame(frame=frame.copy(), timestamp=time.time())
+        self._cached_frame = CachedFrame(frame=frame.copy())
 
     def get_cached_frame(self) -> Optional[Image.Image]:
         if self._cached_frame is None:
@@ -51,22 +49,3 @@ def get_output_frame(self, frozen: bool) -> Image.Image:
             if cached is not None:
                 return cached
         return self.capture_screen()
-
-
-_default_capture = ScreenCapture()
-
-
-def capture_screen() -> Image.Image:
-    return _default_capture.capture_screen()
-
-
-def save_frame_to_buffer(frame: Image.Image) -> None:
-    _default_capture.save_frame_to_buffer(frame)
-
-
-def get_cached_frame() -> Optional[Image.Image]:
-    return _default_capture.get_cached_frame()
-
-
-def get_output_frame(frozen: bool) -> Image.Image:
-    return _default_capture.get_output_frame(frozen)
diff --git a/src/veyoff/filter.py b/src/veyoff/filter.py
index eb4723f..7ad086d 100644
--- a/src/veyoff/filter.py
+++ b/src/veyoff/filter.py
@@ -1,11 +1,14 @@
 from __future__ import annotations
 
+import logging
 from dataclasses import dataclass
 from pathlib import Path
 from typing import Iterable, Sequence
 
 from PIL import Image, ImageDraw
 
+logger = logging.getLogger(__name__)
+
 try:
     from Xlib import X, display
 except Exception:  # pragma: no cover - optional dependency in headless env
@@ -39,6 +42,7 @@ def _walk_windows(node, items: list[WindowInfo]) -> None:
     try:
         children = node.query_tree().children
     except Exception:
+        logger.warning("Failed to query window tree", exc_info=True)
         return
 
     for child in children: