Matlab错误:索引超出矩阵尺寸 [英] Matlab error: Index exceeds matrix dimensions

问题描述

我正在尝试对音频文件执行STFT.我需要获取每个窗口的fft.

I'm trying to perform STFT on an audio file. I need to get the fft of each window.

我使用了以下代码.

[wave,fs] = wavread('40.wav'); 
w_length = 1024;
for v = 1:w_length:length(wave)
    data_sub = wave(v:v+w_length);
    subsection_fft = fft(data_sub);
    figure(1)
    plot(subsection_fft)
end

但是我收到以下错误消息.

But i get the following error.

??? Index exceeds matrix dimensions.
Error in ==> chk at 7
    data_sub = wave(v:v+w_length);

你能告诉我我该怎么做才能纠正这个问题.

Can you tell me what I can do to rectify this.

推荐答案

如错误消息所述，您正在尝试访问wave中的位置，而该位置不存在.

As the error message says, you are trying to access a position in wave tat does not exist.

请参见以下示例:

a    = rand(7,1);
step = 4;

1:step:7
ans =
     1     5

当v = 5时，您将尝试访问位置v:v+step，即5到9，但a最多只能定义7个元素.

when v = 5, you will try to access position v:v+step, i.e. 5 to 9, but a is only defined up to 7 elements.

在您的情况下，wave的定义最高为length(wave)，但是在上一次迭代中，您将越界.

In your case, wave is defined up to length(wave), but on the last iteration you will go out of bounds.

为避免这种情况，方法是对末端序列进行采样并减去序列的长度:

To avoid it, on approach would be to sample the end sequences and subtract the length of the sequence:

pos = (1+w_length:w_length:length(wave))-w_length
for v = pos
% do stuff
end

但是，您将剩下一些未处理的部分，您将在最后一次迭代时在循环之外进行处理.

However, you will be left with some unprocessed part which you will have to do outside of the loop as last iteration.

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