g this dynamically it is possible to change a given clock frequency by only a small percentages.

This circuit processes an incoming audio data stream by analyzing the frequencies and storing them as a dynamic formant profile in the BRAM. It is then read out with a different frequency and resynthesized using an appropriate combination of smoothing and overlap. The method is similar in some ways to granular synthesis but features several improvements. The high sampling rate of modern Cyclone III - FPGAs, combined with sophisticated filtering, comes with good results. The FFT and iFFT can be processed in a very precise way. By using any frequency, the pitch of the output can be modulated extremely. The extracted formant profile can be applied to the input data stream to reduce artefacts.

By using digital up-conversion with enhanced filtering techniques very low distortion to the signal is added. Resampling can also be performed beyond clock domain boundaries using the dynamic resampler module (read here) if necessary.

Read more details about the function of the circuit in the article about the Pitching Module.