@aeva The traditional chorus effect is sound + sound * vibrato. I always thought it was a sine wave vibrato, but others in this thread seem to be suggesting saw wave.
If the vibrato is balanced and starts with taking the pitch lower youāll never need samples from the future. Right when the vibrato cursor catches up to the present, itās time to get behind again.
So overall the formula is out[x] = in[x] + in[x + offset] where offset is a sine wave that starts at 0 and goes to -1 and back to 0.