双门限端点检测。因为低噪声导致假过零率的产生，进行了算法改进。可以直接调用函数运行，亲测-Dual threshold endpoint detection. Because of the low noise cause false over-produce zero rate, the algorithm was improved. It can directly call the function run, pro-test

《从零开始学爬虫》的配套资料（PPT和源码）("Learning Reptiles from Zero" (PPT and Source))