opencv - OpenCV将帧附加到现有视频（.avi）文件？

Question

我有一个小问题。是否可以使用 OpenCV 将新帧添加（附加）到现有的 .avi 视频文件，而不覆盖整个文件？我在带有 QT 的 Windows7 上使用 OpenCV2.4.2。

Answer 1

如果要使用 OpenCV，则必须读取和写入所有数据内容。

import cv2
import os

# this two lines are for loading the videos.
# in this case the video are named as: cut1.mp4, cut2.mp4, ..., cut15.mp4
# videofiles = [n for n in os.listdir('.') if n[0]=='c' and n[-4:]=='.mp4']
# videofiles = sorted(videofiles, key=lambda item: int( item.partition('.')[0][3:]))


videofiles = [n for n in os.listdir('.') if n[0]=='c' and n[-4:]=='.avi']
videofiles = sorted(videofiles, key=lambda item: int( item.partition('.')[0][3:]))

video_index = 0
cap = cv2.VideoCapture(videofiles[0])

# video resolution: 1624x1234 px
# out = cv2.VideoWriter("video.avi", 
#                       cv2.cv.CV_FOURCC('F','M','P', '4'), 
#                       15, (1624, 1234), 1)

# fourcc = cv2.VideoWriter_fourcc(*'MP4V')
# out = cv2.VideoWriter('cutout.mp4', fourcc, 20, (640, 480))

fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('cutout.avi', fourcc, 20.0, (640, 480))

while(cap.isOpened()):
    ret, frame = cap.read()
    if frame is None:
        print ("end of video " + str(video_index) + " .. next one now")
        video_index += 1
        if video_index >= len(videofiles):
            break
        cap = cv2.VideoCapture(videofiles[ video_index ])
        ret, frame = cap.read()
    cv2.imshow('frame',frame)
    out.write(frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
out.release()
cv2.destroyAllWindows()

print ("end.")

Answer 2

看看VideoWriter类。