Handle zero-detections in SkipFrames counter.

- For zero detections, the age is still incremented
- `_detections`  attrubute is set to None

Author: deruyter92

dlclive/pose_estimation_pytorch/runner.py

@@ -82,6 +82,11 @@ def update(self, pose: torch.Tensor, w: int, h: int) -> None:
         self._detections = dict(boxes=bboxes, scores=torch.ones(num_det))
         self._age += 1
 
+    def next_frame(self) -> None:
+        """Increment the frame counter and set detections to None (to handle no detections)"""
+        self._detections = None
+        self._age += 1
+
 
 @dataclass
 class TopDownConfig:
@@ -199,7 +204,10 @@ def get_pose(self, frame: np.ndarray) -> np.ndarray:
                 if self.single_animal or self.n_individuals == 1:
                     zero_pose = np.zeros((self.n_bodyparts, 3))
                 else:
-                    zero_pose = np.zeros((self.n_individuals, self.n_bodyparts, 3))              
+                    zero_pose = np.zeros((self.n_individuals, self.n_bodyparts, 3))
+                # Update skip_frames even when returning early to maintain frame counter
+                if self.top_down_config.skip_frames is not None:
+                    self.top_down_config.skip_frames.next_frame()
                 return zero_pose
 
             tensor = frame_batch  # still CHW, batched