如何使用opencv和python在每千帧中打印一个？

Question

我试着在视频的每千帧中保存一帧。下面是我目前使用的代码：

import cv2
import numpy as np
import os
# Playing video from file:
cap = cv2.VideoCapture('D:/01 Projects/AMAZON CATALYST PROJECT/Surgery1.mpg')
try:
    if not os.path.exists('D:/01 Projects/AMAZON CATALYST PROJECT/data_surg1'):
    os.makedirs('D:/01 Projects/AMAZON CATALYST PROJECT/data_surg1')
except OSError:
    print ('Error: Creating directory of data_surg1')
currentFrame = 0
while(True):
    # Capture frame-by-frame
    if currentFrame > 0:
        cap.set(cv2.CAP_PROP_POS_MSEC,currentFrame) 
    ret, frame = cap.read()

    # Saves image of the current frame in jpg file
    name = 'D:/01 Projects/AMAZON CATALYST PROJECT/data_surg1/frame' + str(currentFrame/1000) + '.jpg'
    print ('Creating...' + name)
    cv2.imwrite(name, frame)

    # To stop duplicate images
    currentFrame += 1000

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

但是，我不确定这是否正确地保存了它。当我查看文件资源管理器中的帧时，这些数字最初非常高，然后与前面的图像相比，形成一个顺序的帧号。我正在使用Python2.7和OpenCV3.3。

Answer 1

为了存储某些帧而不是基于时间的保存，下面的脚本可以工作：

import cv2
import numpy as np
import os
# Playing video from file:
cap = cv2.VideoCapture('D:/01 Projects/AMAZON CATALYST PROJECT/Surgery1.mpg')
try:
    if not os.path.exists('D:/01 Projects/AMAZON CATALYST PROJECT/data_surg1'):
    os.makedirs('D:/01 Projects/AMAZON CATALYST PROJECT/data_surg1')
except OSError:
    print ('Error: Creating directory of data_surg1')
currentFrame = 0
while(True):
    # Capture frame-by-frame
    if currentFrame > 0:
        cap.set(cv2.CAP_PROP_POS_FRAMES,currentFrame) 
    ret, frame = cap.read()

    # Saves image of the current frame in jpg file
    name = 'D:/01 Projects/AMAZON CATALYST PROJECT/data_surg1/frame' + str(currentFrame/1000) + '.jpg'
    print ('Creating...' + name)
    cv2.imwrite(name, frame)

    # To stop duplicate images
    currentFrame += 1

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()