在OpenCV中调整图像大小时未捕获的异常

Question

我试图使用opencv调整函数的大小，该函数在套接字传输的连续循环中调用，我得到了这个错误

2017-04-10 15:46:47.200 python[1541:16193] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'
*** First throw call stack:
(
    0   CoreFoundation                      0x00007fff8ce2b37b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x00007fffa1c1f48d objc_exception_throw + 48
    2   CoreFoundation                      0x00007fff8cd44b5c -[__NSArrayM objectAtIndex:] + 204
    3   libopencv_highgui.2.4.dylib         0x0000000114d31280 _ZN13CvCaptureFileC2EPKc + 350
    4   libopencv_highgui.2.4.dylib         0x0000000114d2fcf2 _Z32cvCreateFileCapture_AVFoundationPKc + 34
    5   libopencv_highgui.2.4.dylib         0x0000000114d237ee cvCreateFileCapture + 14
    6   libopencv_highgui.2.4.dylib         0x0000000114d23a9e _ZN2cv12VideoCapture4openERKNSt3__112basic_stringIcNS1_11char_traitsIcEENS1_9allocatorIcEEEE + 64
    7   libopencv_highgui.2.4.dylib         0x0000000114d238fe _ZN2cv12VideoCaptureC2ERKNSt3__112basic_stringIcNS1_11char_traitsIcEENS1_9allocatorIcEEEE + 42
    8   cv2.so                              0x00000001144ccbce _ZL34pyopencv_VideoCapture_VideoCaptureP7_objectS0_S0_ + 275
    9   libpython2.7.dylib                  0x000000010e6c61bd PyEval_EvalFrameEx + 30141
    10  libpython2.7.dylib                  0x000000010e6be8f2 PyEval_EvalCodeEx + 1538
    11  libpython2.7.dylib                  0x000000010e64943c function_call + 364
    12  libpython2.7.dylib                  0x000000010e623333 PyObject_Call + 99
    13  libpython2.7.dylib                  0x000000010e6305b6 instancemethod_call + 182
    14  libpython2.7.dylib                  0x000000010e623333 PyObject_Call + 99
    15  libpython2.7.dylib                  0x000000010e6ca80d PyEval_CallObjectWithKeywords + 93
    16  libpython2.7.dylib                  0x000000010e62e5c6 PyInstance_New + 134
    17  libpython2.7.dylib                  0x000000010e623333 PyObject_Call + 99
    18  libpython2.7.dylib                  0x000000010e6c5e8f PyEval_EvalFrameEx + 29327
    19  libpython2.7.dylib                  0x000000010e6cb0b2 fast_function + 274
    20  libpython2.7.dylib                  0x000000010e6c5db3 PyEval_EvalFrameEx + 29107
    21  libpython2.7.dylib                  0x000000010e6cb0b2 fast_function + 274
    22  libpython2.7.dylib                  0x000000010e6c5db3 PyEval_EvalFrameEx + 29107
    23  libpython2.7.dylib                  0x000000010e6be8f2 PyEval_EvalCodeEx + 1538
    24  libpython2.7.dylib                  0x000000010e6be2e6 PyEval_EvalCode + 54
    25  libpython2.7.dylib                  0x000000010e6ed254 PyRun_FileExFlags + 164
    26  libpython2.7.dylib                  0x000000010e6ecdd1 PyRun_SimpleFileExFlags + 769
    27  libpython2.7.dylib                  0x000000010e702a12 Py_Main + 3154
    28  python                              0x000000010e610f24 start + 52
)
libc++abi.dylib: terminating with uncaught exception of type NSException
Abort trap: 6

我使用的代码我假设生成此错误是

import numpy as np
import cv2

class video_read():
    def __init__(self, filename):
        self.cap = cv2.VideoCapture(filename)

    def read_frames(self):
        frame  = self.cap.read()[1]
        image = cv2.imencode('.png', frame)[1]
        image_resized = cv2.resize(image, (width/10, height/10))
        return image_resized

有人能指出我做错了什么叫做这个例外吗？