OpenCV 视频中的播放循环选项 [英] Playback loop option in OpenCV videos

问题描述

我正在尝试为 OpenCV 视频构建一个播放循环选项.我的程序使用 Python 多处理，并有一个按钮通过 queue4 发送 loopswitch 调用来启用或禁用循环选项.我的具体问题是我的视频在最后一帧冻结，我想知道 vidFile.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 1) 行是否正确使用cv2.VideoCapture.set() 方法，确实应该将视频带回到第 1 帧并重播(我认为应该如此).

I am trying to build a playback loop option for an OpenCV video. My program uses Python multiprocessing, and has a button send loopswitch calls through queue4 to enable or disable the loop option. My specific problem is that my video freezes on the last frame, and I would like to know if the line vidFile.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 1) is a correct use of the cv2.VideoCapture.set() method, and should indeed take the video back to frame 1 and replay it (as I think it should).

在修改我的代码后，它现在触发了运行时 C++ 错误，但没有给出其他精度.根据这个答案，似乎使用 cv2.VideoCapture.set() 跳转帧之间是越野车.有没有人管过?

After revising my code, it now triggers a runtime C++ error, but no other precisions are given. According to this answer, it would seem that using cv2.VideoCapture.set() to jump between frame is buggy. Has anyone managed it anyway?

谢谢，

我的捕获过程代码(queue和queue2是进出队列):

My code for the capture process (queueand queue2 are in and out queues):

def image_capture(queue, con, queue2, queue4):
    videopath = con.recv()
    vidFile = cv2.VideoCapture(videopath)
    fps = vidFile.get(cv2.cv.CV_CAP_PROP_FPS)
    waitframe = 1/fps
    con.send(waitframe)#sending waitkey duration through pipe to update_image()
    loopswitch = False #init for playing video in a loop 
    while True:
        if queue4.empty():
           pass
        else:
           queueval = queue4.get()
            if queueval=='loop':
               if loopswitch==False:
                  loopswitch = True
               elif loopswitch==True:
                  loopswitch = False
        try:
            flag, frame=vidFile.read()
            if flag==0:
               if loopswitch==False:
                  queue2.put(None)
                  break
               elif loopswitch==True:
                  vidFile.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 1)
                  continue
            else:                
               queue2.put(frame)
               cv2.waitKey(waitframe)
        except:
            continue

推荐答案

我通过将 vidFile.set (cv2.cv.CV_CAP_PROP_POS_FRAMES, 1) 替换为 vidFile.set(cv2.cv.CV_CAP_PROP_POS_AVI_RATIO, 0)，虽然这仅适用于 .avi 文件.

I partially solved it by replacing vidFile.set (cv2.cv.CV_CAP_PROP_POS_FRAMES, 1) by vidFile.set(cv2.cv.CV_CAP_PROP_POS_AVI_RATIO, 0), although this works for .avi files only.

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