g771编码，安卓采用c++ ndk的方式，获取pcm后转为g711格式(G771 encoding, Android using c++ NDK way, after the acquisition of PCM, converted to g711 format)

检测8K采样频率，16位PCM码流的DTMF信号 标准的DTMF双频的检测还是可以的 误差检测可能不是很精确......以后再优化 压缩包里有C源码，build出来的elf文件，原始PCM码流(Detect 8K sampling frequency, 16 bit PCM bitstream DTMF signal Standard DTMF dual frequency detection is fine Error detection may not be accurate...