SigmaStudio allows me to use either single-precision or double precision for most filters in the library. When should I use single and when should I use double?
The SigmaStudio help document recommends that you use double-precision for filters with cutoff frequencies near or below 10% of the sample rate, or when the Q is very high.
There is a brief technical explanation of the differences here:
This is a very good document describing fixed/floating and single/double architectures and the advantages/disadvantages of each:
Basically, for a single-precision filter in the SigmaDSP, you use 28 bits for the coefficient storage, whereas the double-precision version uses 56 bits.
In most general purpose fixed point DSPs, the bit depth is lower (like 16 bits in Blackfin), so double-precision is the norm for most audio filters, regardless of cutoff frequency or Q.
This FAQ was generated from the following discussion: When should I use single precision or double precision filters?