Sliding DFT

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A sliding DFT is a recursive complex FIR filter bank that calculates short-time Fourier transform sample-by-sample. Unlike FFT, the sDFT calculation for each bin is independent of each other, making it ideal for single-bin STFT and even constant-Q transform but this technique are limited by having only integer K otherwise, the sDFT goes out of phase but this is not in case on some sDFT implementations that allows non-integer K.

The sliding DFT can also have asymmetric windowing function by replacing ring buffers with an IIR exponential decay and it can be cascaded to further increase rolloff.