class_docstr: Visualize action predictions for videos or folder of images with precomputed
  and ground-truth boxes in AVA format.
class_docstr_tok: ["Visualize","action","predictions","for","videos","or","folder","of","images","with","precomputed","and","ground-truth","boxes","in","AVA","format","."]
docstr: Return a clip corresponding to a keyframe index for visualization.
  Args:
      keyframe_idx (int): keyframe index.
docstr_tok: ["Return","a","clip","corresponding","to","a","keyframe","index","for","visualization",".","Args",":","keyframe_idx","(","int",")",":","keyframe","index","."]
code: def _get_keyframe_clip(self, keyframe_idx):
      """
      Return a clip corresponding to a keyframe index for visualization.
      Args:
          keyframe_idx (int): keyframe index.
      """
      start_idx = max(0, keyframe_idx - self.seq_length // 2)
  
      clip = self._get_frame_range(start_idx, self.seq_length)
  
      return clip
  
imports: import numpy
  import os
  import cv2
  import torch
  import tqdm
  import slowfast.utils.checkpoint
  import slowfast.utils.logging
  from slowfast.datasets.ava_helper import parse_bboxes_file
  from slowfast.datasets.cv2_transform import scale, scale_boxes
  from slowfast.datasets.utils import get_sequence
  from slowfast.models import build_model
  from slowfast.utils import misc
  from slowfast.utils.env import pathmgr
  from slowfast.visualization.utils import process_cv2_inputs
  from slowfast.visualization.video_visualizer import VideoVisualizer
label_desc: Use image node_id 8 for calling the AVAVisualizerWithPrecomputedBox obj's underlying member method code with example usage: obj._get_keyframe_clip(keyframe_idx) and returns: clip