信息处理 - 使用 FFTW 进行下采样和上采样 - 吾爱随笔录

我有 2 个具有不同采样率的信号，即 1ms(A) 和 4ms(B)，我尝试根据代码片段对任何一个信号进行上采样/下采样基于 FFT的重新采样，我认为这相当于如何使用 fft 或 dft 重新采样音频中描述了什么

% FFTRESAMPLE Resample a real signal by the ratio p/q
function y = fftResample(x,p,q)

% --- take FFT of signal ---
f = fft(x);

% --- resize in the FFT domain ---
% add/remove the highest frequency components such that len(f) = len2
len1 = length(f);
len2 = round(len1*p/q);
lby2 = 1+len1/2;
if len2 < len1
  % remove some high frequency samples
  d = len1-len2;
  f = f(:);
  f(floor(lby2-(d-1)/2:lby2+(d-1)/2)) = [];
elseif len2 > len1
  % add some high frequency zero samples
  d = len2-len1;
  lby2 = floor(lby2);
  f = f(:);
  f = [f(1:lby2); zeros(d,1); f(lby2+1:end)];
end

% --- take the IFFT ---
% odd number of sample removal/addition may make the FFT of a real signal
% asymmetric and artificially introduce imaginary components - we take the
% real value of the IFFT to remove these, at the cost of not being able to
% reample complex signals
y = real(ifft(f));

即，使用 FFTW 库在 C++ 中重新实现了 fftResample。

问题是由于零填充，输出失真。我对 Singal 处理比较陌生，如果用户能帮助我理解，我将不胜感激：

如果我使用正确的代码片段来上采样/下采样？
突出上采样（A 到 4 毫秒）与下采样（B 到 1 毫秒）相比的优势？