python QThread and pydc1394

Question

I am developing an application for image acquisition. I am using PyQt4, pydc1394 (libdc1394 Python wrapper for firewire camera) on a MacOS sierra and the camera is AVT Marlin F131B. I managed to write a program that can acquire images from the camera, however, this program crushes after 10min (this time may vary on different computers) returning a Segmentation Fault.

Initially, I was suspecting a memory leak in the pydc1394. However, when I run the code with QThread.emit deactivated, the code runs very well. The problem raises up when I try to connect the main window to the Qthread object.

My code is attached. Do you have any idea about what is going on please?

Thank you

from PyQt4 import QtGui, QtCore
from pydc1394 import DC1394Library, Camera
from threading import Thread
from datetime import datetime as dt
import time, sys, os, cv2
import numpy as np

class AcquisitionThread(QtCore.QThread):
    sig = QtCore.pyqtSignal(object)

    def __init__(self,cam):
        super(AcquisitionThread,self).__init__()

        self._cam = cam
        self._running = True
        self.start()
        print 'acquisition thread initiated'


    def run(self):
        while self._cam.running and self._running:
            frame = self._cam.current_image
            timestamp = frame.timestamp
            image = np.asarray(frame[:,:])
            self.sig.emit(frame)
            now_time = str(dt.now())
        return 

    def terminate(self):
        self._running = False
        print 'acquisition thread terminated'
        self.wait()
        print "Exited with success"

class MainWindow(QtGui.QWidget):
    def __init__(self):
        super(MainWindow,self).__init__()
        self.resize(700,540)
        self.move(300,300)
        self.setWindowTitle("Camera Acquisition")
        self.scene = QtGui.QGraphicsScene(self)
        self.view = QtGui.QGraphicsView(self.scene)
        self.view.setSizeIncrement(2,2)
        self.vbox = QtGui.QVBoxLayout()
        self.vbox.addWidget(self.view)
        self.setLayout(self.vbox)

        #initiate camera
        l = DC1394Library()
        try:
            list_cameras = l.enumerate_cameras()
        except:
            list_cameras = []

        if len(list_cameras) > 0:
            print len(list_cameras), "camera(s) found:"
            for i,c in enumerate(list_cameras):
                print i,"\t",c['guid']
        else:
            print "No camera was found. Program exiting ..."
            sys.exit()
        self._cam = Camera(l,guid = l.enumerate_cameras()[0]['guid'])

        #start camera 
        self._cam.start(interactive=True)
        print "camera started"
        time.sleep(1)

        self.acquisitionThread = AcquisitionThread(self._cam)
        self.acquisitionThread.sig.connect(self.displayImage)

        self.show()

    def displayImage(self,frame):
        timestamp = frame.timestamp
        #print timestamp
        now_time = str(dt.now())

        print now_time,"\t",timestamp
        img = np.asarray(frame[:,:])
        h,w = img.shape
        pix = QtGui.QPixmap(QtGui.QImage(img.tostring(),w,h,QtGui.QImage.Format_RGB888).rgbSwapped())
        self.scene.clear()
        self.scene.addPixmap(pix)
        #print "done displaying"

    def closeEvent(self,event):
        self._cam.stop()
        print "camera stopped"
        self._cam.close()
        print "camera closed"
        self.acquisitionThread.terminate()

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    mainWindow = MainWindow()
    sys.exit(app.exec_())