code: def nframes(self):
          
          length = ctypes.c_long()
          size = ctypes.c_int(ctypes.sizeof(length))
          check(_coreaudio.ExtAudioFileGetProperty(
              self._obj, PROP_LENGTH, ctypes.byref(size), ctypes.byref(length)
          ))
          return length.value
docs: Gets the number of frames in the source file.