class_docstr: Base video dataset for VID, MOT and VIS tasks.
class_docstr_tok: ["Base","video","dataset","for","VID",",","MOT","and","VIS","tasks","."]
docstr: Get length of one video.
  
  Args:
      idx (int): Index of video.
  
  Returns:
      int (int): The length of the video.
docstr_tok: ["Get","length","of","one","video",".","Args",":","idx","(","int",")",":","Index","of","video",".","Returns",":","int","(","int",")",":","The","length","of","the","video","."]
code: def get_len_per_video(self, idx):
      """Get length of one video.
  
      Args:
          idx (int): Index of video.
  
      Returns:
          int (int): The length of the video.
      """
      return len(self.get_data_info(idx)["images"])
  
file_path: mmdetection/mmdet/datasets/base_video_dataset.py
imports: import copy
  import os.path
  from collections import defaultdict
  from typing import Any, List, Tuple
  import mmengine.fileio
  from mmengine.dataset import BaseDataset
  from mmengine.logging import print_log
  from mmdet.datasets.api_wrappers import COCO
  from mmdet.registry import DATASETS
label_desc: Use image node_id 8 for calling the BaseVideoDataset obj's underlying member method code with example usage: obj.get_len_per_video(idx) and returns: len