最近在搞视频检测问题,在用到将视频分帧保存为图片时,图片可以保存,但是会出现(-215:Assertion failed) !_img.empty() in function 'cv::imwrite'问题而不能正常运行,在检查代码、检查路径等措施均无果后,了解了视频分帧的原理后,才解决了问题,就这一个问题,解决了两天才解决,心态炸裂。缺少分帧结束的判断条件,在写入前,加上:
if frame is None;
break
else:
#导入必备的文件库
import cv2
import numpy as np
import matplotlib.pyplot as plt
#读取视频并分帧为图片
def video_to_frame(video_path,save_path):
video = cv2.VideoCapture(video_path)
index = 0
if video.isOpened():
f =int(video.get(cv2.CAP_PROP_FPS)) #读取视频帧率
print("The video's fps is ",f) #显示视频帧率
rval,frame = video.read() #读取视频帧
else:
rval = False
while rval:
print(index)
rval,frame = video.read()
cv2.imwrite(save_path + "/"+ str(index)+".jpg",frame)
index += 1
if __name__ == "__main__":
video_to_frame(video_path="C:/Users/15603917325/Desktop/video_coal/coal/video/6.mp4",
save_path="C:/Users/15603917325/Desktop/video_coal/coal/pictures_coal")
print("succeed")
出现报错的原因很简单,在使用rval,frame读取视频的帧时,帧图片保存在frame对应的索引里。而在写入图片时,没有加入判断条件,当视频被分帧结束后,cv2.imread函数还在将空白信息写入文件夹,所以会出现报错,因此,只要在 cv2.imwrite(save_path + "/"+ str(index)+".jpg",frame)代码前一行加入判断条件,判断分帧结束后,停止写入即可。加入判断条件:
if frame is None:
break
else:
就可以正确导入分帧后的图片了
在写入前加上判断条件:
#导入必备的文件库
import cv2
import numpy as np
import matplotlib.pyplot as plt
#读取视频并分帧为图片
def video_to_frame(video_path,save_path):
video = cv2.VideoCapture(video_path)
index = 0
if video.isOpened():
f =int(video.get(cv2.CAP_PROP_FPS)) #读取视频帧率
print("The video's fps is ",f) #显示视频帧率
rval,frame = video.read() #读取视频帧
else:
rval = False
while rval:
print(index)
rval,frame = video.read()
if frame is None:
break
else:
cv2.imwrite(save_path + "/"+ str(index)+".jpg",frame)
index += 1
if __name__ == "__main__":
video_to_frame(video_path="C:/Users/15603917325/Desktop/video_coal/coal/video/6.mp4",
save_path="C:/Users/15603917325/Desktop/video_coal/coal/pictures_coal")
print("succeed")
正确输出分帧后的图片,并保存在文件夹中:
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