python中cv2的基本操作——视频、图片的读写

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'''
总结cv2相关内容
'''

import cv2
import numpy as np

'''
读图片
'''
image_path = '/data/weichai/0817_choice_frame/8.4_sortheast/1.jpg'
image = cv2.imread(image_path) 
# image是一个矩阵。shape: (hight, weight, channel)


'''
保存图片
'''
output_path = '/home/liulihao/test/demo.jpg'
save_image = np.zeros([200,100,3])
cv2.imwrite(output_path, save_image)
# save_image是一个矩阵，shape: (hight, weight, channel)


'''
读视频
'''
input_video = '/data/cylinder_demo/raw_data/qiping_merge_20210824.avi'
video_reader = cv2.VideoCapture(input_video)
fps = video_reader.get(5)

frame_id = 0
have_more_frame, frame = video_reader.read()
# have_more_frame是一个布尔变量，代表此帧之后视频中是否还有帧
# frame是图片转化成的矩阵。shape: (hight, weight, channel)

while have_more_frame:
        
        '''此处添加具体操作'''
        # print(frame_id)

        frame_id += 1
        have_more_frame, frame = video_reader.read()

video_reader.release()


'''
保存视频
'''
output_video_path = "/home/liulihao/test/test.avi"
output_fps = 30
output_height, output_width,_ = image.shape

video_writer = cv2.VideoWriter(
        output_video_path,
        # cv2.VideoWriter_fourcc(*'MP4V'),
        cv2.VideoWriter_fourcc(*'XVID'),
        # cv2.VideoWriter_fourcc('I', '4', '2', '0'),
        # cv2.VideoWriter_fourcc('M','J','P','G'), # https://docs.opencv.org/master/dd/d43/tutorial_py_video_display.html
        output_fps,  # fps 每秒的帧数
        (output_width, output_height),  # resolution
)

for i in range(30):
        video_writer.write(image)

video_writer.release()