Biquad filters - Q vs. S (slope)

I am using the Text-in EQ filter block, and calculating biquad coefficients in an microcontroller to safeload in to an ADAU1462.

After tracking down a bug I have learned that the Q/Slope field on the text-in EQ block is Q when using a parametric filter or HPF/LPF, but is 'Slope' when using a a shelving filter.

Slope and Q are not the same, they are calculated in different ways. This is fine, I have now successfully implemented the correct calculations, but it would be much more obvious to the user if you changed the filter block so that rather than 'Q/Slp' it displayed 'Q' whilst set to a type of filter that uses Q, and 'Slope' whilst set to a shelving filter.

The info on the difference is hidden away in the formulas given on the 'General Filters' wiki page (the difference is not explained on the Text-In filter wiki page). A lot of users probably don't need to calculate biquads on the fly so would not look at the formulas and may never realise the difference.

Audio Signal Processors

SigmaDSP Audio Processors

adau1462