Question

在我对具有恒定抽取因子的矢量进行下采样后，我想将矢量上采样回原始采样率（在执行某些分析之后）。但是，我正在努力进行上采样。

对于下采样，我从Accelerate框架应用vDSP_desamp，对于上采样，我尝试应用vDSP_vlint：

// Create some test data for input vector
float inputData[10] = {0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9};

int inputLength = 10;
int decimationFactor = 2; // Downsample by factor 2
int downSampledLength = inputLength/decimationFactor;

// Allocate downsampled output vector
float* downSampledData = malloc(downSampledLength*sizeof(float));

// Create filter (average samples)
float* filter = malloc(decimationFactor*sizeof(float));

for (int i = 0; i < decimationFactor; ++i){
    filter[i] = 1.0/decimationFactor;
}

// Downsample and average
vDSP_desamp(inputData,
            (vDSP_Stride) decimationFactor,
            filter,
            downSampledData,
            (vDSP_Length) downSampledLength,  // Downsample to 5 samples
            (vDSP_Length) decimationFactor );


free(filter);

使用此代码的downSampledData输出为：

0.05, 0.25, 0.45, 0.65, 0.85

要将（已处理的）数据向量上采样回原始采样率，请使用以下代码：

// For this example downSampledData is just copied to processedData ... 
float* processedData =  malloc(downSampledLength*sizeof(float));
processedData = downSampledData; 


//  Create vector used by vDSP_vlint to indicate interpolation constants.
float* b = malloc(downSampledLength*sizeof(float));
for (int i = 0; i < downSampledLength; i++) {
    b[i] = i + 0.5;
}

// Allocate data vector for upsampled data
float* upSampledData = malloc(inputLength*sizeof(float));

// Upsample and interpolate
vDSP_vlint (processedData,
            b,
            1,
            upSampledData,
            1,
            (vDSP_Length) inputLength, // Resample back to 10 samples
            (vDSP_Length) downSampledLength);

但是，upSampledData的输出是

0.15,0.35,0.55,0.75,0.43,0.05,0.05,0.05,0.08,0.12

显然不正确。我该如何申请vDSP_vlint？或者我应该使用其他功能来对数据进行上采样？

使用加速对数据进行上采样的问题

0 个答案: