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DSP: add Sylvain's optimized power spectrum calculation (without sqrt)

This commit is contained in:
Christian Daniel 2012-11-04 20:41:05 +01:00
parent 663c87ee1a
commit 0d3e0c3c26
1 changed files with 4 additions and 3 deletions
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7
dsp/spectrum.cpp
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@ -57,11 +57,12 @@ size_t Spectrum::work(SampleVector::const_iterator begin, SampleVector::const_it
m_fft.transform(&m_fftIn[0], &m_fftOut[0]);
// extract power spectrum and reorder buckets
Real ofs = 20.0f * log10f(1.0f / m_fftSize);
Real mult = (10.0f / log2f(10.0f));
for(size_t i = 0; i < m_fftSize; i++) {
Complex c = m_fftOut[((i + (m_fftSize >> 1)) & (m_fftSize - 1))];
Real v = sqrt(c.real() * c.real() + c.imag() * c.imag());
v /= (Real)m_fftSize;
v = 20.0 * log10(v);
Real v = c.real() * c.real() + c.imag() * c.imag();
v = mult * log2f(v) + ofs;
m_logPowerSpectrum[i] = v;
}