error in using fftoneside

问题

Hi I'm trying to calculate mfcc for which i'm windowing. I have seen this one post I'm getting error in fftOneSide.
my code is

    waveFile='test_preEmphasis.wav';
    [y, fs]=wavread(waveFile);

    n=512;
    t=(1:n)'/fs;
    startIndex=30418;
    endIndex=startIndex+n-1;

    original=y(startIndex:endIndex);
    windowed=original.*hamming(n);
    [mag1, phase1, freq1]=fftOneSide(original, fs);
    [mag2, phase2, freq2]=fftOneSide(windowed, fs);

    subplot(3,2,1); plot(original); grid on; axis([-inf inf -1 1]); 
    title('Original signal');
    subplot(3,2,2); plot(windowed); grid on; axis([-inf inf -1 1]);  
    title('Windowedsignal');
    subplot(3,2,3); plot(freq1, mag1); grid on; 
    title('Energy spectrum (linear scale)');
    subplot(3,2,4); plot(freq2, mag2); grid on; 
    title('Energy spectrum (linear scale)');
    subplot(3,2,5); plot(freq1, 20*log(mag1)); grid on; 
    axis([-inf inf -80 120]); title('Energy spectrum (db)');
    subplot(3,2,6); plot(freq2, 20*log(mag2)); grid on; axis([-inf inf -80 120]);  
    title('Energy spectrum (db)');

the error i'm getting is

    ??? Undefined function or method 'fftOneSide' for input arguments of type 'double'.

any help is appreciated thanks

回答1:

This is a really old post, it'd be neat if someone still cared. I just provided what I believe to be the answer in the recent post below, which I arrived at after a fair bit of frustration: Undefined function 'fftOneSide' for input arguments of type 'double'.

It should be noted here there's a call to a file, which I'm not sure if the author had originally or not. I suspect all the problems are related to a similarly named file in the sourcecode.

If you look at my discussion in the other post, within the function definition there is a call to a method demo with a file - which isn't present if you just have the function definition, not the original file. Calling [mag1, phase1, freq1]=fftOneSide(original, fs,1), after you comment out the first line if nargin <1... and the demo routine worked fine on my machine with the code which I'll show below. Having the third argument equal to 1 guarantees that the code will run the print routines, which is important.

In case the other thread is closed, I just want to show the output, when the input is manually defined, and I call [mag1, phase1, freq1]=fftOneSide(original, fs,1) on the properly edited method, with the inputs as in the original post shown below (notice the call is to original in fftOneSide..in the other post it was like this as well.. I believe the call was was meant to be instead for windowed, but I don't have the signals toolbox with hamming anyways):

fs=8000;
t=(1:512)'/fs; %'// <-- prevents string markdown
f=306.396;
original=sin(2*pi*f*t)+0.2*randn(length(t),1);
% windowed=original.*hamming(length(t)); % defined in other post
[mag1,phase1,freq1]=fftOneSide(original,fs); % I call fftOneSide(original,fs,1);

The output is as follows (source code below!)

Anyways, here's the source code in case anyone wants to use this function

function [magSpec, phaseSpec, freq, powerSpecInDb]=fftOneSide(signal, fs, plotOpt) 
% fftOneSide: One-sided FFT for real signals 
%   Usage: [magSpec, phaseSpec, freq, powerSpecInDb]=fftOneSide(signal, fs) 
% 
%   For example: 
%       [y, fs]=wavread('welcome.wav'); 
%       frameSize=512; 
%       startIndex=2047; 
%       signal=y(startIndex:startIndex+frameSize+1); 
%       signal=signal.*hamming(length(signal)); 
%       plotOpt=1; 
%       [magSpec, phaseSpec, freq, powerSpecInDb]=fftOneSide(signal, fs, plotOpt); 

%   Roger Jang, 20060411, 20070506 

if nargin<1, selfdemo; return; end %=== (MathBio: Comment this out!)
if nargin<2, fs=1; end 
if nargin<3, plotOpt=0; end 

N = length(signal);         % Signal length 
freqStep = fs/N;            % Frequency resolution 
time = (0:N-1)/fs;          % Time vector 
z = fft(signal);            % Spectrum 
freq = freqStep*(0:N/2);        % Frequency vector 
z = z(1:length(freq));          % One side 
z(2:end-1)=2*z(2:end-1);        % Assuming N is even, symmetric data is multiplied by 2
magSpec=abs(z);             % Magnitude spectrum 
phaseSpec=unwrap(angle(z));     % Phase spectrum 
powerSpecInDb=20*log(magSpec+realmin);  % Power in db 

if plotOpt 
    % ====== Plot time-domain signals 
    subplot(3,1,1); 
    plot(time, signal, '.-'); 
    title(sprintf('Input signals (fs=%d)', fs)); 
    xlabel('Time (seconds)'); ylabel('Amplitude'); axis tight 
    % ====== Plot spectral power 
    subplot(3,1,2); 
    plot(freq, powerSpecInDb, '.-'); grid on 
    title('Power spectrum'); 
    xlabel('Frequency (Hz)'); ylabel('Power (db)'); axis tight 
    % ====== Plot phase 
    subplot(3,1,3); 
    plot(freq, phaseSpec, '.-'); grid on 
    title('Phase'); 
    xlabel('Frequency (Hz)'); ylabel('Phase (Radian)'); axis tight 
    end 

% ====== Self demo (MathBio: Comment all of this out! )
function selfdemo 
[y, fs]=wavread('welcome.wav'); 
frameSize=512; 
startIndex=2047; 
signal=y(startIndex:startIndex+frameSize+1); 
signal=signal.*hamming(length(signal)); 
[magSpec, phaseSpec, freq, powerSpecInDb]=feval(mfilename, signal, fs, 1);

来源：https://stackoverflow.com/questions/19535738/error-in-using-fftoneside

标签

matlab

window

fft