# MFCC process confusion

I have read through many papers related to the Mel-frequency cepstrum coefficient (MFCC): I have some confusion about the MFCC process:

1. Many of the papers say that I have to do a FT (Fourier Transform) on the log-spectrum to obtain cepstrum (as mentioned in Wikipedia : definition of power cepstrum)

2. Many say I have to do an IFT (Inverse Fourier Transform) on log-spectrum to obtain cepstrum.

3. Many refer to the DCT-II (Discrete cosine Transform-2) on the Mel-log-spectrum to obtain MFCC.

My question is, which one is right:

1. FT or IFT?

2. If the IFT is correct than why are they using DCT-II instead of IDCT-II, since the DCT-II is similar to DFT or FT?

(hence, the IDFT or IFT should be similar to IDCT-II)

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## migrated from stackoverflow.comNov 7 '12 at 15:30

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