func spectral_analyze(af *sndfile.File, Frames, FftBins int) (s *SpectralAnalysis) {
SpectrumBands := FftBins/2 - 1
s = new(SpectralAnalysis)
s.Frames = make([]SpecFrame, Frames)
var maxPower float64
for f := 0; f < Frames; f++ {
full := make([]float64, int32(FftBins)*af.Format.Channels)
_, err := af.ReadFrames(full)
if err != nil {
panic(err)
}
samps := mixdown(full, int(af.Format.Channels))
c := fftw.Alloc1d(len(samps))
o := fftw.Alloc1d(len(samps))
for i := 0; i < FftBins; i++ {
hann := (float64(1) - math.Cos(float64(i)/float64(FftBins))*math.Pi*2.0)
hamming := hann*0.92 + 0.08
c[i] = complex(samps[i]*hamming, 0)
defer func() {
if x := recover(); x != nil {
fmt.Fprintf(os.Stderr, "panicked at i = %d\n", i)
}
}()
}
p := fftw.PlanDft1d(c, o, fftw.Forward, 0)
p.Execute()
s.Frames[f] = make(SpecFrame, SpectrumBands)
for i := 0; i < SpectrumBands; i++ {
pow := math.Sqrt(math.Pow(real(c[i+1]), 2) + math.Pow(imag(c[i+1]), 2))
s.Frames[f][i] = pow
if pow > maxPower {
maxPower = pow
}
}
}
for f := 0; f < Frames; f++ {
for i := 0; i < SpectrumBands; i++ {
s.Frames[f][i] /= maxPower
}
}
s.Freqs = make([]float64, SpectrumBands)
for i, _ := range s.Freqs {
s.Freqs[i] = float64(((float64(44100) * 0.5) / float64(SpectrumBands+1)) * float64(i+1))
}
return
}
func (f *Fseq) pdetect(af *sndfile.File, lower, upper float64, length, fftbins int) {
windowWidth := SampleRate / lower
t := math.Trunc(windowWidth)
for index := 0; index < length; index++ {
var width uint
if int(math.Trunc((windowWidth-t)*10.0)) < 5 {
width = uint(t)
} else {
width = uint(math.Ceil(windowWidth))
}
full := make([]float64, int32(width*2)*af.Format.Channels)
_, err := af.Seek(af.Format.Frames*int64(index)/int64(length), sndfile.Set)
if err != nil {
panic(err)
}
read, err := af.ReadFrames(full)
if err != nil {
panic(err)
}
if sumread := read; read != int64(width*2) {
_, err = af.Seek(0, sndfile.Set)
if err != nil {
panic(err)
}
read, err = af.ReadFrames(full[(int32(sumread) * af.Format.Channels):])
if err != nil {
panic(err)
}
if read+sumread != int64(width*2) {
width = uint((read + sumread) / 2)
}
}
samps := mixdown(full, int(af.Format.Channels))
bestComb := uint(0)
bestPower := float64(-999999)
combLow := width
combHigh := uint(math.Ceil(SampleRate / upper))
for comb := combLow; comb >= combHigh; comb -= QuickCombInterval {
var power float64
for w := uint(0); w < comb; w++ {
power += samps[w] * samps[w+comb]
}
if power > bestPower {
bestPower = power
bestComb = comb
}
}
f.Pitches = append(f.Pitches, SampleRate/float64(bestComb))
}
}