'channel count or 0 for unknown'

@property
def channels(self):

    if hasattr(self, 'pce_channels'):
        return self.pce_channels
    conf = getattr(self, 'extensionChannelConfiguration', self.channelConfiguration)
    if (conf == 1):
        if (self.psPresentFlag == (-1)):
            return 0
        elif (self.psPresentFlag == 1):
            return 2
        else:
            return 1
    elif (conf == 7):
        return 8
    elif (conf > 7):
        return 0
    else:
        return conf
