I need some help,
what is the reference-value, to calculate dB from values
returne by FFT?
Normaly, the SPL is L=10 log(Ix/I0) with I0=10E-12 W/m^2.
In the MPEG-Source code, all FFT-values should be normalized to the reference-level of 96dB SPL, but how do I know, what the value calculated from FFT is, when I don't have the reference-value.
Thank You for help me