'**SUMMARY**
Rewind the Video source back to the given frame.
Available for only video sources.
**PARAMETERS**
start - the number of the frame that you want to rewind to.
if not provided, the video source would be rewound
to the starting frame number you provided or rewound
to the beginning.
**RETURNS**
None
**EXAMPLES**
>>> cam = VirtualCamera("filename.avi", "video", 120)
>>> i=0
>>> while i<60:
... cam.getImage().show()
... i+=1
>>> cam.rewind()'

def rewind(self, start=None):

    if (self.sourcetype == 'video'):
        if (not start):
            cv.SetCaptureProperty(self.capture, cv.CV_CAP_PROP_POS_FRAMES, (self.start - 1))
        else:
            if (start == 0):
                start = 1
            cv.SetCaptureProperty(self.capture, cv.CV_CAP_PROP_POS_FRAMES, (start - 1))
    else:
        self.counter = 0
