如何频谱-逆采样音频信号 [英] How to Spectrum-inverse a sampled audio signal

问题描述

我要寻找c表示频谱逆采样音频信号，一个简单的（伪）$ C $。 理想的情况是C ++

I am looking for a simple (pseudo)code that spectrum-inverse a sampled audio signal. Ideally C++

在code应支持不同的采样率（16/32 / 48KHz的）。

The code should support different sample rates (16/32/48KHz).

推荐答案

按 FS / 2 混合信号将交换高频和低频 - 想旋转的频谱围绕单位圆半圈。你可以每隔一个采样乘以-1实现这一旋转。

Mixing the signal by Fs/2 will swap high frequencies and low frequencies - think of rotating the spectrum around the unit circle by half a turn. You can achieve this rotation by multiplying every other sample by -1.

按 FS / 2 混合相当于由 EXP（j * PI * n）的混合。如果 X 是输入是输出，

Mixing by Fs/2 is equivalent to mixing by exp(j*pi*n). If x is the input and y the output,

y[n] = x[n] * exp(j*pi*n) = x[n] * [cos(pi*n) + j*sin(pi*n)]

这简化了轻松，因为罪（PI * N） 0和 COS（PI * N）是交替1，-1。

This simplifies easily because sin(pi*n) is 0, and cos(pi*n) is alternating 1,-1.

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