c++ 获取麦克风声音频率

要获取麦克风声音频率，你需要进行语音信号处理。这个过程中可能需要用到快速傅里叶变换（FFT）来分析频谱。以下是一个简单的例子，你可以参考一下：

#include <iostream>
#include <cmath>
#include <complex>
#include <vector>
#include <fftw3.h>
#include <portaudio.h>

#define SAMPLE_RATE 44100
#define FRAMES_PER_BUFFER 512

using namespace std;

// 回调函数
static int audioCallback(const void *inputBuffer, void *outputBuffer,
                         unsigned long framesPerBuffer,
                         const PaStreamCallbackTimeInfo *timeInfo,
                         PaStreamCallbackFlags statusFlags,
                         void *userData)
{
    float *input = (float *)inputBuffer;
    vector<double> buffer(framesPerBuffer);
    for (int i = 0; i < framesPerBuffer; i++) {
        buffer[i] = (double)(*input++);
    }
    
    // FFT
    fftw_complex *out = (fftw_complex *)fftw_malloc(sizeof(fftw_complex) * framesPerBuffer);
    fftw_plan plan = fftw_plan_dft_r2c_1d(framesPerBuffer, &buffer[0], out, FFTW_ESTIMATE);
    fftw_execute(plan);
    
    // 计算频率
    double maxAmplitude = 0.0;
    double maxFrequency = 0.0;
    for (int i = 0; i < framesPerBuffer / 2; i++) {
        double amplitude = sqrt(out[i][0] * out[i][0] + out[i][1] * out[i][1]);
        if (amplitude > maxAmplitude) {
            maxAmplitude = amplitude;
            maxFrequency = i * SAMPLE_RATE / (double)framesPerBuffer;
        }
    }
    cout << "Frequency: " << maxFrequency << " Hz" << endl;
    
    fftw_destroy_plan(plan);
    fftw_free(out);
    
    return paContinue;
}

int main()
{
    PaError err = Pa_Initialize();
    if (err != paNoError) {
        cerr << "Failed to initialize PortAudio: " << Pa_GetErrorText(err) << endl;
        return -1;
    }
    
    PaStream *stream;
    err = Pa_OpenDefaultStream(&stream, 1, 0, paFloat32, SAMPLE_RATE, FRAMES_PER_BUFFER, audioCallback, NULL);
    if (err != paNoError) {
        cerr << "Failed to open stream: " << Pa_GetErrorText(err) << endl;
        Pa_Terminate();
        return -1;
    }
    
    err = Pa_StartStream(stream);
    if (err != paNoError) {
        cerr << "Failed to start stream: " << Pa_GetErrorText(err) << endl;
        Pa_CloseStream(stream);
        Pa_Terminate();
        return -1;
    }
    
    cout << "Press Enter to exit." << endl;
    cin.get();
    
    err = Pa_StopStream(stream);
    if (err != paNoError) {
        cerr << "Failed to stop stream: " << Pa_GetErrorText(err) << endl;
    }
    
    err = Pa_CloseStream(stream);
    if (err != paNoError) {
        cerr << "Failed to close stream: " << Pa_GetErrorText(err) << endl;
    }
    
    Pa_Terminate();
    
    return 0;
}

这个例子使用了PortAudio库来获取麦克风输入，并且使用了FFTW库来进行FFT计算。在回调函数中，我们首先将输入数据复制到一个vector中，然后进行FFT计算，最后找到最大幅值的频率。注意，这个例子只能获取到一帧音频的频率，如果要获取连续的音频频率，你需要在程序中添加相应的逻辑。