WIP: extractfreq: a-weighting

master
J. David Lee 2019-12-07 11:18:50 +01:00
parent d7a8d4ec74
commit 90fbc089f4
3 changed files with 93 additions and 25 deletions

View File

@ -0,0 +1,9 @@
package extractfreq
import "math"
func AWeight(f float64) float64 {
return (148693636.0 * f * f * f * f) / ((424.36 + f*f) * math.Sqrt(
(f*f+11599.29)*(f*f+544496.41)) *
(f*f + 148693636.0))
}

View File

@ -2,9 +2,7 @@ package extractfreq
import (
"log"
"math"
"git.crumpington.com/public/jlaudio/lib/util"
"gonum.org/v1/gonum/floats"
"gonum.org/v1/gonum/stat"
)
@ -31,14 +29,11 @@ func NewHarmonicWindow(
// TODO: At higher harmonic numbers, the harmonics are going to be spaced
// more cloesly together. That means that the window size must shrink.
winSizeCents := float64(150)
//winSizeCents := float64(150)
// To start, we create a window around the approximate harmonic location.
idxPeak := int((fFundamental * harmonic) / deltaF)
winSize := int(
math.Round(
winSizeCents * util.CentDeltaFreq(fFundamental*harmonic) /
deltaF))
winSize := int(0.5 * fFundamental / deltaF)
amps := rawAmps[idxPeak-winSize : idxPeak+winSize]
freqs := rawFreqs[idxPeak-winSize : idxPeak+winSize]
@ -54,14 +49,17 @@ func NewHarmonicWindow(
ampPeak := amps[idxPeak]
log.Printf("%0.2f: %0.4f", harmonic, (ampPeak-mean)/std)
// TODO: Actual interpolation.
return &HarmonicWindow{
Harmonic: harmonic,
Amps: amps,
Freqs: freqs,
IdxPeak: idxPeak,
AmpPeak: ampPeak,
AmpMean: mean,
AmpStd: std,
Harmonic: harmonic,
Amps: amps,
Freqs: freqs,
IdxPeak: idxPeak,
IdxPeakInterp: float64(idxPeak),
FreqPeakInterp: freqs[idxPeak],
AmpPeak: ampPeak,
AmpMean: mean,
AmpStd: std,
}
}

View File

@ -3,6 +3,7 @@ package extractfreq
import (
"fmt"
"log"
"math"
"math/cmplx"
"git.crumpington.com/public/jlaudio/lib/flac"
@ -13,7 +14,12 @@ import (
"gonum.org/v1/plot/vg"
)
func PlotFFT(path string, nSamples int, targetFreq float64) {
// Steps:
//
// * Create amplitude spectrum (abs of FFT).
// * Multiply by A-weight curve
// * Take log10 of result
func PlotFFT(path string, nSamples int, fFundamental float64) {
L, R, err := flac.Load(path)
if err != nil {
panic(err)
@ -32,19 +38,21 @@ func PlotFFT(path string, nSamples int, targetFreq float64) {
cCoeffs := fft.Coefficients(nil, data)
amps := make([]float64, len(cCoeffs))
freqs := make([]float64, len(cCoeffs))
ampMax := float64(0)
for i := range freqs {
amps[i] = cmplx.Abs(cCoeffs[i])
if amps[i] > ampMax {
ampMax = amps[i]
}
freqs[i] = fft.Freq(i) * 48000
if freqs[i] < 20 {
amps[i] = 0
} else {
amps[i] = math.Log10(cmplx.Abs(cCoeffs[i]) * AWeight(freqs[i]))
}
}
// Normalize coefficients.
for i := range amps {
amps[i] /= ampMax
}
//for i := range amps {
//amps[i] /= ampMax
//}
// Find highest N peaks and sort by size.
/*
// Use a moving window to search for local peaks.
@ -63,11 +71,42 @@ func PlotFFT(path string, nSamples int, targetFreq float64) {
*/
// Find frequency window around midi note.
harmonics := []float64{0.25, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
p, err := plot.New()
if err != nil {
panic(err)
}
log.Printf("Making points...")
pts := make(plotter.XYs, 0, len(amps))
for i := range amps {
if freqs[i] < 20 || freqs[i] > 16000 {
continue
}
pts = append(pts, plotter.XY{
X: freqs[i],
Y: amps[i],
})
}
log.Printf("Plotting...")
if err = plotutil.AddLinePoints(p, "fft", pts); err != nil {
panic(err)
}
//p.Y.Scale = plot.LogScale{}
p.X.Scale = plot.LogScale{}
log.Printf("Saving...")
if err := p.Save(16*vg.Inch, 8*vg.Inch, "fft.png"); err != nil {
panic(err)
}
harmonics := []float64{0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
hws := []*HarmonicWindow{}
for _, harmonic := range harmonics {
hw := NewHarmonicWindow(
targetFreq,
fFundamental,
harmonic,
amps,
freqs)
@ -99,5 +138,27 @@ func PlotFFT(path string, nSamples int, targetFreq float64) {
if err := p.Save(8*vg.Inch, 8*vg.Inch, filename); err != nil {
panic(err)
}
hws = append(hws, hw)
}
pts = make(plotter.XYs, len(hws))
for i, hw := range hws[:11] {
pts[i].X = hw.Harmonic
pts[i].Y = hw.FreqPeakInterp
}
p, err = plot.New()
if err != nil {
panic(err)
}
if err = plotutil.AddScatters(p, "", pts); err != nil {
panic(err)
}
log.Printf("Saving...")
if err := p.Save(8*vg.Inch, 8*vg.Inch, "harmonics.png"); err != nil {
panic(err)
}
}