我正在尝试为OpenCV视频构建播放循环选项。我的程序使用Python多处理，并有一个按钮通过loopswitch发送queue4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，我想知道行vidFile.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 1)是否正确使用cv2.VideoCapture.set()方法，并且确实应该将视频带回第1帧并重播（我认为应该如此）。
修改我的代码后，它现在会触发运行时C ++错误，但没有给出其他精度。
根据{{3}}，似乎使用cv2.VideoCapture.set()在帧之间跳转是错误的。有人管理过吗？
谢谢，
我的捕获过程代码（queue和queue2是进出队列）：
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
答案 0 :(得分：2)
我通过(cv2.cv.CV_CAP_PROP_POS_FRAMES, 1)替换vidFile.set vidFile.set(cv2.cv.CV_CAP_PROP_POS_AVI_RATIO, 0)来部分解决它，尽管这仅适用于.avi文件。
答案 1 :(得分：1)
我可以通过在帧计数达到cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT)时使用if语句然后将帧计数和cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, num)重置为相同的值来获得循环视频播放。以下示例为我循环播放视频。
import cv2
cap = cv2.VideoCapture('path/to/video')
frame_counter = 0
while(True):
# Capture frame-by-frame
ret, frame = cap.read()
frame_counter += 1
#If the last frame is reached, reset the capture and the frame_counter
if frame_counter == cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT):
frame_counter = 0 #Or whatever as long as it is the same as next line
cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 0)
# Our operations on the frame come here
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# Display the resulting frame
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()
它还可以重新捕捉视频，而不是重置帧数：
if frame_counter == cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT):
frame_counter = 0
cap = cv2.VideoCapture(video_name)
所以至少我可以使用cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, num)来循环播放视频。如果重置为第0帧而不是第1帧（如使用avi方法）会发生什么？
答案 2 :(得分：1)
对于python3，opencv3.1.0，raspberry pi 3
[
{
"Strength": 12,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
},
{
"Strength": 0,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
},
{
"Strength": 0,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
},
{
"Strength": 0,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
},
{
"Strength": 0,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
},
{
"Strength": 0,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
},
{
"Strength": 0,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
},
{
"Strength": 0,
"Intelligence": 0,
"Defense": 0,
"Resistance": 0,
"Accuracy": 0,
"Agility": 0,
"Speed": 0,
"CurrentAP": 0,
"CurrentHP": 0,
"Affinity": 0,
"Poison": 0,
"Weakness": 0,
"Paralysis": 0,
"LifeStatus": 0
}
]
答案 3 :(得分：0)
对于C ++专家：
void openVideo() {
cap.open(videoName);
if (!cap.isOpened()) {
std::cout << "Video file not loaded!" << std::endl;
}
numberOfFrames = (int)cap.get(cv::CAP_PROP_FRAME_COUNT);
//--- GRAB AND WRITE LOOP
std::cout << "Start grabbing" << std::endl
<< "Press any key to terminate" << std::endl;
for (;;)
{
// wait for a new frame from camera and store it into 'frame'
cap.read(frame);
frameCounter++;
// check if we succeeded
if (frameCounter == numberOfFrames) {
frameCounter = 0;
cap.set(cv::CAP_PROP_POS_FRAMES, 0);
}
if (frame.empty()) {
std::cerr << "ERROR! blank frame grabbed\n";
break;
}
// show live and wait for a key with timeout long enough to show images
cv::imshow("Live", frame);
if (cv::waitKey(5) >= 0)
break;
}
// the camera will be deinitialized automatically in VideoCapture destructor
}
答案 4 :(得分：0)
self.cap =cv2.VideoCapture(self.filename)
while True:
ret,frameset = self.cap.read()
if self.cap.get(1)>self.cap.get(7)-2:#video loop
self.cap.set(1,0)#if frame count > than total frame number, next frame will be zero
cv2.imshow("G",frameset)
key = cv2.waitKey(1)
if key == 27:
break
self.cap.release()
cv2.destroyAllWindows()