Question

我正在关注如何制作倒谱用于检测语音共振峰并使用iPhone Accelerate框架对其进行编码的an article。但是，结果并不像文章所期望的那样。对于清音部分（文章中的图3），它在前几个箱中显示较小的值。但是，当我的代码运行时，清音部分的值很大（朝向1.0），看起来更像是一个有声部分。

这是我的代码：

// copy buffer data into a separate array and apply hamming window
// don't use leadlength because we copied to beginning of buffer
int offset = (int)(s * stepSize);
float *hamBuffer = malloc(n*sizeof(float));
for (int i=0; i < n; i++)
    hamBuffer[i] = hpBuffer[offset+i] * ((1.0f-0.46f) - 0.46f*cos(TWOPI*i/((float)n-1.0f)));

// configure float array into acceptable input array format (interleaved)
vDSP_ctoz((COMPLEX*)hamBuffer, 2, &complexArray, 1, halfN);

// free ham buffer
free(hamBuffer);

// run FFT
vDSP_fft_zrip(setupReal, &complexArray, stride, log2n, FFT_FORWARD);

// Absolute square (equivalent to mag^2)
complexArray.imagp[0] = 0.0f;
vDSP_zvmags(&complexArray, 1, complexArray.realp, 1, halfN);
bzero(complexArray.imagp, (halfN) * sizeof(float));

// scale
float scale = 1.0f / (2.0f*(float)n);
vDSP_vsmul(complexArray.realp, 1, &scale, complexArray.realp, 1, halfN);

// get log of absolute values for passing to inverse FFT for cepstrum
float *logmag = malloc(sizeof(float)*halfN);
for (int i=0; i < halfN; i++)
    logmag[i] = log10f(fabsf(complexArray.realp[i]));

// configure float array into acceptable input array format (interleaved)
vDSP_ctoz((COMPLEX*)logmag, 2, &complexArray, 1, halfN/2);

// create cepstrum
vDSP_fft_zrip(setupReal, &complexArray, stride, log2n-1, FFT_INVERSE);

// scale again
scale = (float) 1.0 / (2 * n);
vDSP_vsmul(complexArray.realp, 1, &scale, complexArray.realp, 1, halfN);
vDSP_vsmul(complexArray.imagp, 1, &scale, complexArray.imagp, 1, halfN);

//convert interleaved to real
float *displayData = malloc(sizeof(float)*n);
vDSP_ztoc(&complexArray, 1, (COMPLEX*)displayData, 2, halfN);    

// print cepstrum to debug window
for (int i=0; i < halfN; i++)
    printf("%f\r\n", displayData[i]);

以下是前几个箱子的结果：

他们确实'稳定'朝零，但前几个数字比我预期的无声部分大。我的代码看起来不正确吗？我想我非常仔细地阅读了这篇文章。为什么我在清洁部分的前几个箱中得到如此大的值？

Apple Accelerate框架产生了倒谱意外的结果

0 个答案: