WIP: extractfreq
parent
a5b5cce493
commit
78c9070763
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@ -0,0 +1,56 @@
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package extractfreq
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import (
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"math"
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"git.crumpington.com/public/jlaudio/lib/util"
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"gonum.org/v1/gonum/stat"
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)
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type HarmonicWindow struct {
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TargetFreq float64
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Amps []float64
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Freqs []float64
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Idx0 int
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IdxPeak int
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IdxPeakInterp float64
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FreqPeakInterp float64
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AmpPeak float64
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AmpMean float64
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AmpStd float64
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}
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// Construct a window around the harmonic peak with a width of 100 cents.
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func NewHarmonicWindow(
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amps []float64,
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freqs []float64,
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targetFreq float64,
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idxPeak int,
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) *HarmonicWindow {
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deltaF := freqs[1] - freqs[0] // Size of frequency bins.
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fCenter := freqs[idxPeak] // Center frequency.
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// Create a window approximately 200 cents in width.
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deltaIdx := int(math.Round(deltaF / (100 * util.CentDeltaFreq(fCenter))))
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idxMin := idxPeak - deltaIdx
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idxMax := idxPeak + deltaIdx
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if idxMin < 0 {
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idxMin = 0
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}
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if idxMax > len(freqs) {
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idxMax = len(freqs)
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}
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hw := &HarmonicWindow{
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TargetFreq: targetFreq,
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Amps: amps[idxMin:idxMax],
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Freqs: freqs[idxMin:idxMax],
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IdxPeak: idxPeak,
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AmpPeak: amps[idxPeak],
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}
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hw.AmpMean, hw.AmpStd = stat.MeanStdDev(hw.Amps, nil)
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return hw
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}
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@ -0,0 +1,89 @@
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package extractfreq
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import (
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"log"
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"math/cmplx"
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"git.crumpington.com/public/jlaudio/lib/flac"
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"gonum.org/v1/gonum/fourier"
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"gonum.org/v1/plot"
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"gonum.org/v1/plot/plotter"
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"gonum.org/v1/plot/plotutil"
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"gonum.org/v1/plot/vg"
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)
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func PlotFFT(path string, nSamples int, targetFreq float64) {
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L, R, err := flac.Load(path)
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if err != nil {
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panic(err)
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}
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if nSamples < len(L) {
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nSamples = len(L)
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}
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data := make([]float64, nSamples)
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for i := range data {
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data[i] = float64(L[i]) + float64(R[i])
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}
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fft := fourier.NewFFT(nSamples)
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cCoeffs := fft.Coefficients(nil, data)
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amps := make([]float64, len(cCoeffs))
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freqs := make([]float64, len(cCoeffs))
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ampMax := float64(0)
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for i := range freqs {
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amps[i] = cmplx.Abs(cCoeffs[i])
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if amps[i] > ampMax {
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ampMax = amps[i]
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}
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freqs[i] = fft.Freq(i) * 48000
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}
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// Normalize coefficients.
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for i := range amps {
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amps[i] /= ampMax
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}
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/*
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// Use a moving window to search for local peaks.
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hws := []*HarmonicWindow{}
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// Bypass low-frequency samples.
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i := 0
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for i < len(freqs) && freqs[i] < 24 {
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i++
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}
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iCenter := i
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for iC{
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}
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*/
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// Find frequency window around midi note.
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p, err := plot.New()
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if err != nil {
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panic(err)
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}
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log.Printf("Making points...")
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pts := make(plotter.XYs, len(amps))
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for i := range amps {
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pts[i].X = freqs[i]
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pts[i].Y = amps[i]
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}
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log.Printf("Plotting...")
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if err = plotutil.AddLines(p, "fft", pts); err != nil {
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panic(err)
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}
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p.Y.Scale = plot.LogScale{}
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//p.X.Scale = plot.LogScale{}
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log.Printf("Saving...")
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if err := p.Save(8*vg.Inch, 8*vg.Inch, "plot.png"); err != nil {
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panic(err)
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}
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}
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@ -0,0 +1,7 @@
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package extractfreq
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import "testing"
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func TestPlotFFT(t *testing.T) {
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PlotFFT("test_files/440.flac", 96000, 440)
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}
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@ -3,6 +3,16 @@ package util
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import "math"
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// Return the frequency of a given MIDI note number.
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func NoteFreq(n int) float64 {
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return (math.Pow(2, (float64(n)-69)/12)) * 440
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func NoteFreq(n float64) float64 {
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return (math.Pow(2, (n-69)/12)) * 440
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}
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// Return the midi note number for the given frequency.
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func FreqNote(f float64) float64 {
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return 12*math.Log2(f/440) + 69
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}
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// Return the one-cent change in frequency at the given frequency.
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func CentDeltaFreq(f float64) float64 {
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return f * (math.Pow(2, 1/1200.0) - 1)
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}
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@ -7,7 +7,7 @@ import (
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func TestNoteFreq(t *testing.T) {
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type TestCase struct {
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In int
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In float64
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Out float64
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}
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@ -29,3 +29,48 @@ func TestNoteFreq(t *testing.T) {
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}
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}
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}
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func TestFreqNote(t *testing.T) {
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type TestCase struct {
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Out float64
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In float64
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}
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testCases := []TestCase{
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{108, 4186.01},
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{81, 880},
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{69, 440},
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{58, 233.08},
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{57, 220},
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{56, 207.65},
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{55, 196},
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{36, 65.41},
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}
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for _, tc := range testCases {
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out := FreqNote(tc.In)
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if fmt.Sprintf("%.2f", out) != fmt.Sprintf("%.2f", tc.Out) {
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t.Fatalf("%v != %v", out, tc.Out)
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}
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}
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}
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func TestCentDeltaFreq(t *testing.T) {
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type TestCase struct {
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In, Out float64
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}
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testCases := []TestCase{
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{27.5, 0.016},
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{55, 0.032},
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{130.8128, 0.076},
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{440, 0.254},
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}
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for _, tc := range testCases {
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out := CentDeltaFreq(tc.In)
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if fmt.Sprintf("%.3f", out) != fmt.Sprintf("%.3f", tc.Out) {
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t.Fatalf("%v: %v != %v", tc.In, out, tc.Out)
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}
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}
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}
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