Questions tagged [cepstral-analysis]

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1answer
807 views

Verification of all steps needed to extract MFCCs from raw audio data

I need some verification on steps required to extract MFCCs from raw audio as I'm finding that some sources outline them slightly differently. Get raw audio frame Run window function (eg Blackman) on ...
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1answer
320 views

Dynamic Time Warp through SPTK tool

I'm an IT student and got an assignment to do about Dynamic Time Warping(DTW) using the Speech Signal Processing Toolkit (SPTK) and comparing some words spoken by 2 speakers and finding the ...
3
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1answer
802 views

What's the difference between using DFT, IDFT or DCT to calculate cepstrum of a power spectrum?

I've seen different equations that calculate cepstrum from power spectrum, but the equations are not consistent. Some people use Fourier transform, some use the inverse Fourier transform, and some use ...
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1answer
87 views

What is an intuitive explanation of cepstrum for a 12-year-old?

In Feynman's spirit of "If you truly understand a concept, you should be able to explain it clearly" and the explanation should make solid sense. There are two main challenges: The axis of "...
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1answer
147 views

Cepstrum Calculation of Rational Function H(z)

I am trying to solve my first problems at cepstrum calculation. I want to calculate the complex cepstrum $\hat{h}[n]$ of a signal $h[n]$ with Z-Transform: $$H(z)=\frac{(1-0.5z^{-1})(1+4z^{-2})}{(1-0....
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1answer
764 views

Image 2D Real Cepstrum with DFT, Is `ifftshift` Needed?

This is my testing image,it is taken from this paper: I tried to transform it into its real cepstrum domain with this simple MATLAB code: ...
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0answers
80 views

Decoding data hidden using “echo hiding” technique

I'm working on a little project, which centers around steganography. As part of it, I want to implement the audio echo hiding method, but the problem is, I've never done anything related to digital ...
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1answer
1k views

Formula to calculate Cepstral coefficients (not MFCC)

I am currently working with non-audio signals of which I would like to calculate the Cepstrum coefficients with Python so that I can use them with machine learning algorithms. That's probably a quite ...
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1answer
145 views

Intuition behind cepstrum analysis terminology

In multiple books I found a parallel between spectrum-analysis terminology and cepstrum-analysis terminology that says low pass filter $\rightarrow$ short pass lifter I didn't read explicitly what ...
1
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1answer
453 views

Cepstrum: IFFT or FFT to enter the cepstral domain?

I'm trying to implement source-filter separation of some pre-recorded speech in Max/MSP. I'm unsure of whether one uses an FFT to enter the cepstral domain, or an IFFT. Some of the textbooks and ...
3
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0answers
408 views

Linear Frequency Cepstral Coefficients, is Filter bank needed?

I am working on my master thesis on acoustic pattern recognition and have a question to the calculation of cepstral coefficients. I understand the step with a filter bank in MFCC calculation, it is ...
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0answers
197 views

Why the Room Impulse Response (RIR) obtained form cepstrum is not correct?

I generate a synthetic room Room Impulse Response(RIR) function to filter a speech signal, and want to reveal the RIR from the filtered signal by using complex cepstrum. Generating the convolved ...
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1answer
707 views

cceps (complex cepstrum) function in Matlab

My doubt is in regards to the usage of the function cceps in Matlab. The function is giving me the cepstrum for the entire speech signal of 3 or 4sec. This works ...
2
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1answer
134 views

Cepstrum calculus disambiguation

Learning the cepstrum analysis for speech recognition, I have met two different definitions of cepstrum (for discrete signals): $F^{-1}(ln|F(x[n])|)$ . That is, the cepstrum is the inverse Fourier ...
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2answers
440 views

Difference between rceps and cceps in MATLAB

I'm trying to construct a cepstrum using MATLAB built in function but I don't get the difference between MATLAB's functions rceps and cceps. Can anyone explain to me the difference between rceps and ...
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0answers
360 views

Implement Cepstral analysis in Matlab

I have a bit complex time signal. When trying to plot its spectrum, I get some weird result. Denoting the time signal as x and time vector as ...
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0answers
128 views

Closed form solution for the minimum phase of a continuous magnitude response

Let's say I have a continuous real function $F(\omega)$ defined in the region $\omega = [-\pi, \pi]$. Let's also say that I have a minimum phase $z$-domain transfer function $H(z)$ defined as: $$\...
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0answers
98 views

Cepstrum of finite impulse train

In Acero's Spoken language processing (p. 309) it says that the cepstrum of a finite length impulse train $$x[n] = \sum^{M-1}_{k=0} \delta[n-kN]$$ is given by $$\hat{x}[n] = \sum^{ \infty}_{r=1} \frac{...
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1answer
166 views

Is there a way to do a DFT with low latency and fine frequency resolution at low frequencies?

I am learning about the DFT in order to design a fundamental pitch detector for the human singing voice. Using the cepstrum technique. I am concerned about the latency for low frequency detection at &...
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1answer
83 views

Normalizing Cepstrum by Energy

I have separately computed the cepstrum and the energy of a finite discrete-time signal. If the energy of the signal is high, we would expect (on average) larger cepstral values than if the energy of ...
3
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1answer
252 views

Calculating phase response of maximum phase filter using Hilbert Transform

Given only a magnitude response $A(\omega)$ of a minimum phase filter, one can calculate the phase response using the Hilbert Transform: $$θ(ω) = -\mathcal{H}\{\ln(A(\omega)\}$$ This paper suggests ...
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1answer
621 views

Preserving formants using Cepstrum

I've implemented an harmonizer, using Stefan Bernsee's code, which works great. I figured out the logic of finding the root note, and the right harmony in the scale. The only problem is that, my ...
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0answers
228 views

How to interpret the sign of a cepstral coefficient?

I feel like I've got a decent intuition for what the magnitude of a cepstral coefficient represents (i.e. how much of the signal's energy is contained in harmonics of a given wavelength), but I don't ...
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2answers
951 views

Why is cepstrum used in MFCC instead of autocorrelation sequence?

I know that the inverse Fourier transform of the power spectral density $P(k)$ gives the autocorrelation sequence $A(n)$ (By Wiener-Khinchin theorem): $${\cal F}^{-1}\left\{P(k)\right\}=A(n)$$ And ...
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1answer
373 views

MFCC extraction last step DCT or IDCT

I'm confused with the last step of extraction MFCC where we have to take DCT or IDCT. Cepstrum is defined as IDFT of log(power spectrum). Since MFCC are cepstral coefficients so I think we have to ...
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2answers
10k views

How do I interpret the DCT step in the MFCC extraction process?

In most audio processing tasks, one of the most used transformations is MFCC (Mel-frequency cepstral coefficients). I mostly know the math that's behind the MFCC: I understand both the filterbank ...
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1answer
165 views

Recursively obtaining all-pole coefficients from complex cepstral coefficients?

This is a problem from the book Discrete-Time Speech Signal Processing by Thomas Quatieri, Chapter 6 Problem 13: Suppose $h[n]$ is all-pole (minimum-phase) of order $p$. Show that the all-pole (...
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0answers
122 views

Cepstrum: subtracting the mean vs. dividing by the variance

In cepstral speech analysis, it is relatively easy to understand why subtracting the mean removes any "channel" effects (including that of recording equipment and the vocal tract). There is a good ...
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2answers
363 views

Interpreting Cepstrum of plucked string

in my attempts to synthesize a plucked electric guitar string (using supercollider's digital waveguide, which is based on the Karplus-Strong algorithm) I came to a dead end and decided to look that ...
1
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1answer
510 views

How can I use time-series transforms for detecting malware? [closed]

I am student of network security, and very unfamiliar with the domain of signal processing. Do pardon my naivety at asking very basic stuff. My work deals with detecting malicious activity in network ...
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0answers
870 views

bearing frequency detection

I am working on bearing faults detection. I am doing the following steps: signal->mean zero->high pass->hilbert->y->fft->cepstrum of y. my code is: ...
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1answer
148 views

Suggestions for FFT based tools to analyze music - Preferably MATLAB/free software packages [closed]

I am interested in analyzing full length songs for general features of the track which are not otherwise apparent. For e.g., I want to look at various parts of the song with time-frequency plots/...
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1answer
6k views

MFCC Deltas, Delta-Deltas

I have just a quick question about how to calculate Deltas from MFCC. I have found the formula for calculating deltas here: $$d_t=\frac{\sum_{n=1}^{N}n\left(c_{t+n}-c_{t-n}\right)}{2\sum_{n=1}^{N}n^2}...
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1answer
614 views

Can't compute real cepstrum of real signal

I'm trying to compute the real cepstral coefficients of recorded telephone audio in Matlab using the rceps function. On some audio frames (480 samples per frame -- 60ms of audio at 8kHz), I get a ...
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3answers
300 views

Why does the excitation signal appear, separated, at high quefrencies in the cepstrum?

So, I've just begun a speech and language processing course and have found the explanation of the process of getting the cepstrum of a signal and its properties a little confusing. The following is a ...
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0answers
498 views

Questions about Bark scale filter bank implementation for bfcc's

I have a few questions regarding the implementation of Bark scale filter banks for the calculation of bark frequency cepstral coefficients. 1) Which filter shape is most commonly used and why? ...
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0answers
140 views

How to measure the short-time change in an audio signal?

The choice of frame length for calculating the Mel Frequency Cepstral Coefficients of a signal, depend on the how much the signal change over a small time scale. I guess that human speech change ...
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0answers
78 views

Length of frames for calculating cepstral coefficients

For audio classification we are using the cepstral coefficients and their derivatives. Which I calculate using the Matlab libary voicebox. I am looking for some literature for how to choose the frame ...
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1answer
2k views

How to decide the number of cepstral coefficients?

For audio classification we are using cepstral coefficients, but how should I decide the number of coefficients?
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0answers
1k views

DFT, cepstrum, LPC for feature extraction

I am a newbie in speech processing and experimenting to get a feel. I have extracted some speech segments using a window function and I want to find distance between a pair of segments. First, I took ...
4
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1answer
634 views

High Level Process, Calculating Cepstrum When You Only Have Spectrum

I am not a DSP expert, so I would like someone to check my thought process: I have a text file representing the spectrum (calculated by some FFT hardware), and I'd like to calculate a cepstrum. I'm ...
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1answer
1k views

voice recognition vs speech recognition MFCC

I have a basic understanding of the acoustic preprocessing involved in speech recognition: divide the speech into frames, find the mel frequency cepstral coefficients of each frame, construct a ...