videocr_PaddleOCR.ipynb 跑demo遇到的错误 #12

`from videocr import save_subtitles_to_file

#@title OCR parameters
input_file_path = "example_cropped.mp4" #@PARAM {type:"string"}
output_file_path = "example.srt" #@PARAM {type:"string"}
language_code = "ch" #@PARAM {type:"string"}
use_gpu = False #@PARAM {type:"boolean"}
start_time = "00:00" #@PARAM {type:"string"}
end_time = "" #@PARAM {type:"string"}
confidence_threshold = 50 #@PARAM {type:"number"}
similarity_threshold = 80 #@PARAM {type:"number"}
frames_to_skip = 0 #@PARAM {type:"integer"}
crop_x = 40 #@PARAM {type:"integer"}
crop_y = 650 #@PARAM {type:"integer"}
crop_width = 890 #@PARAM {type:"integer"}
crop_height = 69 #@PARAM {type:"integer"}

save_subtitles_to_file(input_file_path, output_file_path, lang=language_code,
time_start=start_time, time_end=end_time,
conf_threshold=confidence_threshold, sim_threshold=similarity_threshold,
use_gpu=use_gpu,
# # Models different from the default mobile models can be downloaded here: https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.3/doc/doc_en/models_list_en.md
det_model_dir='./videocr/model/ch_det_fast', rec_model_dir='./videocr/model/ch_rec_fast',
# brightness_threshold=210, similar_image_threshold=1000 # filters might help
# use_fullframe=True, # note: videocr just assumes horizontal lines of text. vertical text scenario hasn't been implemented yet
frames_to_skip=frames_to_skip, # can skip inference for some frames to speed up the process
crop_x=crop_x, crop_y=crop_y, crop_width=crop_width, crop_height=crop_height)`

报错：
`---------------------------------------------------------------------------
error Traceback (most recent call last)
/tmp/ipykernel_8898/783819912.py in
25 # use_fullframe=True, # note: videocr just assumes horizontal lines of text. vertical text scenario hasn't been implemented yet
26 frames_to_skip=frames_to_skip, # can skip inference for some frames to speed up the process
---> 27 crop_x=crop_x, crop_y=crop_y, crop_width=crop_width, crop_height=crop_height)

~/work/y00580163/videocr-PaddleOCR/videocr/api.py in save_subtitles_to_file(video_path, file_path, lang, time_start, time_end, conf_threshold, sim_threshold, use_fullframe, det_model_dir, rec_model_dir, use_gpu, brightness_threshold, similar_image_threshold, similar_pixel_threshold, frames_to_skip, crop_x, crop_y, crop_width, crop_height)
23 f.write(get_subtitles(
24 video_path, lang, time_start, time_end, conf_threshold,
---> 25 sim_threshold, use_fullframe, det_model_dir, rec_model_dir, use_gpu, brightness_threshold, similar_image_threshold, similar_pixel_threshold, frames_to_skip, crop_x, crop_y, crop_width, crop_height))

~/work/y00580163/videocr-PaddleOCR/videocr/api.py in get_subtitles(video_path, lang, time_start, time_end, conf_threshold, sim_threshold, use_fullframe, det_model_dir, rec_model_dir, use_gpu, brightness_threshold, similar_image_threshold, similar_pixel_threshold, frames_to_skip, crop_x, crop_y, crop_width, crop_height)
10
11 v = Video(video_path, det_model_dir, rec_model_dir)
---> 12 v.run_ocr(use_gpu, lang, time_start, time_end, conf_threshold, use_fullframe, brightness_threshold, similar_image_threshold, similar_pixel_threshold, frames_to_skip, crop_x, crop_y, crop_width, crop_height)
13 return v.get_subtitles(sim_threshold)
14

~/work/y00580163/videocr-PaddleOCR/videocr/video.py in run_ocr(self, use_gpu, lang, time_start, time_end, conf_threshold, use_fullframe, brightness_threshold, similar_image_threshold, similar_pixel_threshold, frames_to_skip, crop_x, crop_y, crop_width, crop_height)
74
75 if similar_image_threshold:
---> 76 grey = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
77 if prev_grey is not None:
78 _, absdiff = cv2.threshold(cv2.absdiff(prev_grey, grey), similar_pixel_threshold, 255, cv2.THRESH_BINARY)

error: OpenCV(4.6.0) /io/opencv/modules/imgproc/src/color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'`