//计算原文件的长度 按分:秒:毫秒计
ms := (WaveHeader.wSampleLength mod WaveHeader.nAvgBytesPerSec)*1000 div WaveHeader.wSampleLength;
s := (WaveHeader.wSampleLength div WaveHeader.nAvgBytesPerSec) mod 60;
m := (WaveHeader.wSampleLength div WaveHeader.nAvgBytesPerSec) div 60;