//filterCutoff is 0..1 (-6 dB point)
/// <summary>Initializes a new instance of the <see cref="IppResampler" /> class.</summary>
/// <param name="inRate">The input sampling rate.</param>
/// <param name="outRate">The output sampling rate.</param>
/// <param name="requestedFilterOrder">The requested filter order.</param>
/// <param name="filterCutoff">The 6-dB cutoff frequency of the anti-aliasing filter
/// as a fraction of the Nyquist frequency. Must be in the range of 0...1.</param>
/// <param name="kaiserAlpha">The alpha parameter of the Kaiser filter.</param>
public IppResampler(int inRate, int outRate, int requestedFilterOrder, float filterCutoff, float kaiserAlpha)
{
this.inRate = inRate;
this.outRate = outRate;
//allocate memory for the resampler structure
int specSize, filterOrder, filterHeight;
IppStatus rc;
rc = Ipp.ippsResamplePolyphaseFixedGetSize_32f(inRate, outRate, requestedFilterOrder, &specSize,
&filterOrder, &filterHeight, IppHintAlgorithm.ippAlgHintFast);
IppException.Check(rc);
//{!} docs suggest to use ippsMalloc_8u(specSize), but that results in memory corruption
pSpec = (IppsResamplingPolyphaseFixed_32f *)Ipp.ippsMalloc_8u(specSize * filterHeight);
//initialize IPP resampler
rc = Ipp.ippsResamplePolyphaseFixedInit_32f(inRate, outRate, filterOrder, filterCutoff,
kaiserAlpha, pSpec, IppHintAlgorithm.ippAlgHintFast);
IppException.Check(rc);
//set up input buffer
inData = new float[filterOrder];
readIndex = readIndex0 = filterOrder / 2;
writeIndex = writeIndex0 = filterOrder;
}
public static extern IppStatus ippsResamplePolyphaseFixed_32f(float *pSrc, int len,
float *pDst, float norm, double *pTime, int *pOutlen,
IppsResamplingPolyphaseFixed_32f *pSpec);
public static extern IppStatus ippsResamplePolyphaseFixedInit_32f(int inRate, int outRate,
int len, float rollf, float alpha, IppsResamplingPolyphaseFixed_32f *pSpec,
IppHintAlgorithm hint);