The demo Chorus/Flanger effect uses a set of FIR Fractional Delay filters which produce samples a 1/8, 2/8, ... 7/8 of a sample delay. It then uses linear interpolation to calculate sampples betweem the ones by the Fractional Delay filters.

The block diagram of a Chorus/Flanger is very similar to the generalised echo block diagram from earlier. The difference is that the time delay can now be modulated.

The demo program is called chorus_flange .