void FFTFrame::doInverseFFT(float* data)
{
// Prepare interleaved data.
float* interleavedData = getUpToDateComplexData();
// Compute inverse transform.
av_rdft_calc(m_inverseContext, interleavedData);
// Scale so that a forward then inverse FFT yields exactly the original data.
const float scale = 1.0 / m_FFTSize;
VectorMath::vsmul(interleavedData, 1, &scale, data, 1, m_FFTSize);
}
void FFTFrame::doInverseFFT(float* data)
{
Ipp32f* complexP = getUpToDateComplexData();
// Compute inverse transform.
ippsDFTInv_PermToR_32f(complexP, reinterpret_cast<Ipp32f*>(data), m_DFTSpec, m_buffer);
// Scale so that a forward then inverse FFT yields exactly the original data.
const float scale = 1.0 / (2 * m_FFTSize);
ippsMulC_32f_I(scale, reinterpret_cast<Ipp32f*>(data), m_FFTSize);
}
void FFTFrame::doInverseFFT(float* data) {
// Prepare interleaved data.
float* interleavedData = getUpToDateComplexData();
// Compute inverse transform.
av_rdft_calc(m_inverseContext, interleavedData);
// Scale so that a forward then inverse FFT yields exactly the original data.
// For some reason av_rdft_calc above returns values that are half of what I
// expect. Hence make the scale factor
// twice as large to compensate for that.
const float scale = 2.0 / m_FFTSize;
VectorMath::vsmul(interleavedData, 1, &scale, data, 1, m_FFTSize);
}
