Question

我将保留解释，我的代码如何工作，非常短。我建议你自己尝试一下这个代码，所以也许你会更好地理解它。我有一个音频文件，并在我的代码中读取它。现在我使用函数FFT从时域切换到频域。但唯一的区别是，我正在对我的音频信号执行STFT。我每隔30ms做一次，直到我的信号长度。我知道，matlab中有许多不同的功能，它们也可以轻松地执行此操作，但是没有给我我需要的结果。现在，我每隔30ms绘制许多不同的频谱。但我把我的信号分成了三个频段。它们被称为LOW，MEDIUM和HIGH。基本上，这意味着我每隔30ms有3个不同的光谱图。我要做的下一步是将所有幅度从一个频谱汇总到一起，这意味着每个频谱有一个值，这是平方的。

现在，我拥有各种光谱的力量！所有这些值都在我的代码中绘制。我只是绘制功率值，否则我的代码执行时间会非常慢。

顺便说一句，代码看起来很长，但有两个for循环。在第一个中，我读取低频谱，当它完成时，第二个从中等和高频谱开始。基本上他们是一样的。我知道，我可以用findpeaks或类似的东西做到这一点。但是我该如何写/拉呢呢？或者做了什么必要的步骤。最后，我收录了一个文件，希望你能看到。我想测量峰值并从红色图中获得它们之间的距离。

修改好吧，我得到了山峰，但不是我想象的方式。我想显示高于5000线的峰值。很抱歉没有在开头清楚。看我的情节，我的意思。我想说我的代码，只应测量峰值，高于5000线。

[pks, locs] = findpeaks(ValuesOfYc); 
p=plot(x,ValuesOfYc,'r-' ,x(locs), pks,'ob');

这就是我在上面的第一个循环中所做的。我该怎么办呢？

clear;
clc;
%% MATLAB
%% read file
%_________________________________________
[y,fs]=audioread('Undertale - Megalovania.wav');
% audioread = read wav -file
% y = contains the audio signal
% fs = 44100
% 'UnchainMyHeart' = name of the wav-file
%_________________________________________
%% PARAMETER FOR STFT
%_________________________________________ 
t_seg=0.03; % length of segment in ms
fftlen = 4096; %FFT-Points

% Defining size of frequency bands
f_low= 1:200;    %lower frequencies
f_medium= 201:600;  %medium frequencies
f_high= 601:1000; %higher frequencies
%__________________________________________
%% CODE

segl =floor(t_seg*fs); 
windowshift=segl/2; 
% defining the size of the window shift
window=hann(segl); 
% apply hann function on segment length (30 ms)
window=window.'; 
% transpose vector
si=1; 
% defining start index
ei=segl; 
% defining end index

N=floor( length(y)/windowshift - 1);
% Calculates the number, how often the window has to shift
% until to length of the audio signal

f1=figure;
    % Generating new window

      f=0:1:fftlen-1;
      f=f/fftlen*fs;
      % defining frequency vector

      Ya=zeros(1,fftlen);

      ValuesOfYc = NaN(1,N);
      ValuesOfYd = NaN(1,N);
      ValuesOfYe = NaN(1,N);

      x =(1:N)*windowshift/fs;
      % defining x-axis

for m= 1:1:N 

      y_a = y(si:ei);
      % a segment is taken out from audio signal length(30ms) 
      y_a= y_a.*window;
      % multiplying segment with window (hanning) 
      Ya=fft(y_a, fftlen);
      % Applying fft on segment
      Yb=abs(Ya(1:end/2)).^2;  
      % Squaring the magnitudes from one-sided spectrum

          drawnow; % Updating the graphical values

      figure(f1);
      % Showing the power values

      %% frequency bands

      y_low = Yb(f_low);  % LOW frequency spectrum

      Yc=sum(y_low);
      % Summing all the power values from one frequency spectrum together
      % so you get one power value from one spectrum 
      ValuesOfYc(m) = Yc;
      %Output values are being saved here, which are generated from the for
      %loop
      % m = start variable from for loop


      [pks, locs] = findpeaks(ValuesOfYc);

      subplot(2,1,1)
      p=plot(x,ValuesOfYc,'r-', x(locs(pks>=5000)), pks(pks>=5000),'ob');  
      p(1).LineWidth =0.5;
      xlabel('time (Audio length)')
      ylabel('Power')
      grid on

      si=si+windowshift; 
      % Updating start index 
      ei=ei+windowshift; 
      % Updating end index

end

for o= 1:1:N

      y_a = y(si:ei);
      % a segment is taken out from audio signal length(30ms) 
      y_a= y_a.*window;
      % multiplying segment with window (hanning) 
      Ya=fft(y_a, fftlen);
      % Applying fft on segment
      Yb=abs(Ya(1:end/2)).^2;  
      % Squaring the magnitudes from one-sided spectrum

          drawnow; % Updating the graphical values

      figure(f1);
      % Showing the power values
[![enter image description here][1]][1]
      %% frequency bands

      y_medium = Yb(f_medium); % MEDIUM frequency spectrum
      y_high = Yb(f_high); % HIGH frequency spectrum

      Yd=sum(y_medium);
      Ye=sum(y_high);
      % Summing all the power values from one frequency spectrum together
      % so you get one power value from one spectrum 
      ValuesOfYd(o) = Yd;
      ValuesOfYe(o) = Ye;
      %Output values are being saved here, which are generated from the for
      %loop
      % m = start variable from for loop

      subplot(2,1,2)
      p=plot(x, ValuesOfYd,'g-', x, ValuesOfYe,'b-' );
      p(1).LineWidth =0.5;
      xlabel('time (Audio length)')
      ylabel('Power')
      grid on

      si=si+windowshift; 
      % Updating start index 
      ei=ei+windowshift; 
      % Updating end index
  end

在我的情节

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