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Hi guys, Can anyone please tell me how to perform fft on an array produced by matlab function 'wavread' and the result plotted on a figure to get the pitch of the wav file? Any help is greatly appreciated. Thanks |
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FFT in Matlab
Started by ●February 17, 2002
Reply by ●February 19, 20022002-02-19
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Hi, FFT in matlab can be done using direct FFT function. let us say k is an array of size N then call fft directly. using fftk= fft(k,N); Once you got fft in the array fftk, you can easily plot isnt it? For more info, you can see the FFT help from MATLAB. %FFT Discrete Fourier transform. % FFT(X) is the discrete Fourier transform (DFT) of vector X. If the % length of X is a power of two, a fast radix-2 fast-Fourier % transform algorithm is used. If the length of X is not a % power of two, a slower non-power-of-two algorithm is employed. % For matrices, the FFT operation is applied to each column. % For N-D arrays, the FFT operation operates on the first % non-singleton dimension. % % FFT(X,N) is the N-point FFT, padded with zeros if X has less % than N points and truncated if it has more. % % FFT(X,[],DIM) or FFT(X,N,DIM) applies the FFT operation across the % dimension DIM. % % For length N input vector x, the DFT is a length N vector X, % with elements % N % X(k) = sum x(n)*exp(-j*2*pi*(k-1)*(n-1)/N), 1 <= k <= N. % n=1 % The inverse DFT (computed by IFFT) is given by % N % x(n) = (1/N) sum X(k)*exp( j*2*pi*(k-1)*(n-1)/N), 1 <= n <= N. % k=1 % % The relationship between the DFT and the Fourier coefficients a and b in % N/2 % x(n) = a0 + sum a(k)*cos(2*pi*k*t(n)/(N*dt))+b(k)*sin(2*pi*k*t(n)/(N*dt)) % k=1 % is % a0 = 2*X(1)/N, a(k) = 2*real(X(k+1))/N, b(k) = 2*imag(X(k+1))/N, % where x is a length N discrete signal sampled at times t with spacing dt. Regards, Sridhar -----Original Message----- From: ngweelee [mailto:] Sent: Monday, February 18, 2002 2:39 AM To: Subject: [matlab] FFT in Matlab Hi guys, Can anyone please tell me how to perform fft on an array produced by matlab function 'wavread' and the result plotted on a figure to get the pitch of the wav file? Any help is greatly appreciated. Thanks _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: To Post: To Leave: Archives: http://www.yahoogroups.com/group/matlab More DSP-Related Groups: http://www.dsprelated.com/groups.php3 ">http://docs.yahoo.com/info/terms/ |
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