音频振幅和分贝互转

template<class T>
inline float amplitudeToDB( T ampval )
{
if( ampval >0 )
return 20 * log10(ampval); 
else
return -20 * log10(-ampval); 
}

float dBToAmplitude( float val)
{
if(val>0)
return pow(10, val/20.0f);
else
return -pow(10, -val/20.0f);
}