Manual STFT to obtain spectrogram of an audio signal

Question

Fernanda Cortes 2019-6-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/467017-manual-stft-to-obtain-spectrogram-of-an-audio-signal

回答： UMAIR RASOOL 2020-8-1

Hi, Im trying to obtain the notes that are on an audio signal by using the spectrogram to know the frequencies on it, but i dont know why this code plots me an empty graph. Can sombody help me please.

[x,fs]= audioread("estrellita.mp3");
dt = 1/44100;
t=0:dt:(117204*dt)-dt;                    
S = zeros(501,117);
windowlength = 1e3;
k = 1;
for jj = 1:117
    y = x(k:k+windowlength-1)';
    ydft = fft(y).*gausswin(1e3);
    S(:,jj) = ydft(1:501);
    k = k+windowlength;
end
F = 0:44100/1000:44100/2;
T = 0:(1e3*dt):(117000*dt)-(1e3*dt);
surf(T,F,20*log10(abs(S)),'EdgeColor','none')
axis xy; axis tight; colormap(jet); view(0,90);
xlabel('Time');
ylabel('Frequency (Hz)');
set(gca,'YDir','Normal')
xlabel('Time (secs)')
ylabel('Freq (Hz)')
title('Short-time Fourier Transform spectrum')