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))
}
}
