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opencv python camera frame grab and display on different threads with safe synchronization
#!/usr/bin/env python
from threading import Thread, Lock
import cv2
class WebcamVideoStream :
def __init__(self, src = 0, width = 320, height = 240) :
self.stream = cv2.VideoCapture(src)
self.stream.set(cv2.cv.CV_CAP_PROP_FRAME_WIDTH, width)
self.stream.set(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT, height)
(self.grabbed, self.frame) = self.stream.read()
self.started = False
self.read_lock = Lock()
def start(self) :
if self.started :
print "already started!!"
return None
self.started = True
self.thread = Thread(target=self.update, args=())
self.thread.start()
return self
def update(self) :
while self.started :
(grabbed, frame) = self.stream.read()
self.read_lock.acquire()
self.grabbed, self.frame = grabbed, frame
self.read_lock.release()
def read(self) :
self.read_lock.acquire()
frame = self.frame.copy()
self.read_lock.release()
return frame
def stop(self) :
self.started = False
self.thread.join()
def __exit__(self, exc_type, exc_value, traceback) :
self.stream.release()
if __name__ == "__main__" :
vs = WebcamVideoStream().start()
while True :
frame = vs.read()
cv2.imshow('webcam', frame)
if cv2.waitKey(1) == 27 :
break
vs.stop()
cv2.destroyAllWindows()
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