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在我使用恒定抽取因子对向量进行下采样后，我想将向量上采样回原始采样率（在执行一些分析之后）。但是，我正在为上采样而苦苦挣扎。

对于下采样，我应用了 Accelerate 框架中的 vDSP_desamp，而对于上采样，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);

downSampledData使用此代码 的输出是：

0.05, 0.25, 0.45, 0.65, 0.85

要将（处理后的）数据向量上采样回原始采样率，我使用以下代码：

// 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);

然而，输出upSampledData是

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

这显然是不正确的。我应该如何申请vDSP_vlint？还是应该使用其他功能对数据进行上采样？

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