Refactor main.go for improved readability and add detailed comments for functions
This commit is contained in:
534
main.go
534
main.go
@ -2,291 +2,353 @@
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package main
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package main
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import (
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import (
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"flag"
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"flag"
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"fmt"
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"fmt"
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"log"
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"log"
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"math"
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"math"
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"os"
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"os"
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"time"
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"time"
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"github.com/go-audio/audio"
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"github.com/go-audio/audio"
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"github.com/go-audio/wav"
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"github.com/go-audio/wav"
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)
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)
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// Command-line flags
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// Command-line flags
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var (
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var (
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wavFile = flag.String("wav", "", "Path to mono 8kHz WAV file")
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wavFile = flag.String("wav", "", "Path to mono 8kHz WAV file")
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minAms = flag.Int("minA", 1000, "Minimum Tone A duration (ms)")
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minAms = flag.Int("minA", 1000, "Minimum Tone A duration (ms)")
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minBms = flag.Int("minB", 3000, "Minimum Tone B duration (ms)")
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minBms = flag.Int("minB", 3000, "Minimum Tone B duration (ms)")
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gapMaxMs = flag.Int("gap", 5000, "Max gap between A and B (ms)")
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gapMaxMs = flag.Int("gap", 5000, "Max gap between A and B (ms)")
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winMs = flag.Int("win", 100, "Window size (ms)")
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winMs = flag.Int("win", 100, "Window size (ms)")
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hopMs = flag.Int("hop", 50, "Hop size (ms)")
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hopMs = flag.Int("hop", 50, "Hop size (ms)")
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ratioThresh = flag.Float64("ratio", 0.65, "Power ratio threshold for tone detection")
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ratioThresh = flag.Float64("ratio", 0.65, "Power ratio threshold for tone detection")
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rmsThresh = flag.Float64("rms", 300.0, "Minimum RMS for valid signal")
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rmsThresh = flag.Float64("rms", 300.0, "Minimum RMS for valid signal")
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)
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)
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// Goertzel struct for frequency detection
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// Goertzel struct for frequency detection
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type goertzel struct {
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type goertzel struct {
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N int
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N int
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fs float64
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fs float64
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k int
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k int
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coeff float64
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coeff float64
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}
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}
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// newGoertzel initializes and returns a new instance of the Goertzel algorithm for detecting a specific target frequency.
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// Parameters:
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//
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// targetHz - the target frequency in Hertz to detect.
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// fs - the sampling rate in Hertz.
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// N - the number of samples to process.
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//
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// Returns:
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//
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// A pointer to a goertzel struct configured for the specified frequency and sample rate.
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func newGoertzel(targetHz float64, fs float64, N int) *goertzel {
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func newGoertzel(targetHz float64, fs float64, N int) *goertzel {
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g := &goertzel{N: N, fs: fs}
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g := &goertzel{N: N, fs: fs}
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g.k = int(0.5 + (float64(g.N)*targetHz)/fs)
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g.k = int(0.5 + (float64(g.N)*targetHz)/fs)
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omega := (2.0 * math.Pi * float64(g.k)) / float64(g.N)
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omega := (2.0 * math.Pi * float64(g.k)) / float64(g.N)
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g.coeff = 2.0 * math.Cos(omega)
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g.coeff = 2.0 * math.Cos(omega)
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return g
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return g
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}
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}
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// Power computes the power of the target frequency in the input signal x using the Goertzel algorithm.
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// It processes the input slice x of length g.N and returns the squared magnitude of the frequency component
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// specified by g.k. The function is typically used for efficient detection of specific frequencies in a signal.
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func (g *goertzel) Power(x []float64) float64 {
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func (g *goertzel) Power(x []float64) float64 {
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var s0, s1, s2 float64
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var s0, s1, s2 float64
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for i := 0; i < g.N; i++ {
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for i := 0; i < g.N; i++ {
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s0 = x[i] + g.coeff*s1 - s2
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s0 = x[i] + g.coeff*s1 - s2
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s2 = s1
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s2 = s1
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s1 = s0
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s1 = s0
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}
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}
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omega := (2.0 * math.Pi * float64(g.k)) / float64(g.N)
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omega := (2.0 * math.Pi * float64(g.k)) / float64(g.N)
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real := s1 - s2*math.Cos(omega)
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real := s1 - s2*math.Cos(omega)
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imag := s2 * math.Sin(omega)
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imag := s2 * math.Sin(omega)
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return real*real + imag*imag
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return real*real + imag*imag
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}
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}
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// windowHann applies a Hann window to the input slice x in-place.
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// The Hann window is commonly used in signal processing to reduce spectral leakage
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// by tapering the beginning and end of the signal to zero.
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// The function modifies the input slice directly.
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func windowHann(x []float64) {
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func windowHann(x []float64) {
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n := float64(len(x))
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n := float64(len(x))
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for i := range x {
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for i := range x {
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x[i] *= 0.5 * (1.0 - math.Cos(2.0*math.Pi*float64(i)/(n-1.0)))
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x[i] *= 0.5 * (1.0 - math.Cos(2.0*math.Pi*float64(i)/(n-1.0)))
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}
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}
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}
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}
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// pcmToFloat converts a slice of 16-bit PCM audio samples to a slice of float64 values.
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// It processes up to N samples from the input buffer and returns the converted values.
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// If the input buffer has fewer than N samples, only the available samples are converted.
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func pcmToFloat(buf []int16, N int) []float64 {
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func pcmToFloat(buf []int16, N int) []float64 {
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out := make([]float64, N)
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out := make([]float64, N)
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for i := 0; i < N && i < len(buf); i++ {
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for i := 0; i < N && i < len(buf); i++ {
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out[i] = float64(buf[i])
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out[i] = float64(buf[i])
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}
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}
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return out
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return out
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}
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}
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// rmsPCM calculates the root mean square (RMS) value of a slice of 16-bit PCM audio samples.
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// It returns the RMS as a float64, which is a measure of the signal's amplitude.
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// If the input slice is empty, it returns 0.
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func rmsPCM(buf []int16) float64 {
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func rmsPCM(buf []int16) float64 {
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var s float64
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var s float64
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for _, v := range buf {
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for _, v := range buf {
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f := float64(v)
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f := float64(v)
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s += f * f
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s += f * f
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}
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}
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if len(buf) == 0 {
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if len(buf) == 0 {
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return 0
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return 0
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}
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}
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return math.Sqrt(s / float64(len(buf)))
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return math.Sqrt(s / float64(len(buf)))
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}
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}
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// twoToneDetector for detecting tone sequences
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// twoToneDetector for detecting tone sequences
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type twoToneDetector struct {
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type twoToneDetector struct {
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fs int
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fs int
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winN int
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winN int
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hopN int
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hopN int
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ratioThresh float64
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ratioThresh float64
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rmsThresh float64
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rmsThresh float64
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minAms int
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minAms int
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minBms int
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minBms int
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gapMaxMs int
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gapMaxMs int
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freqs []float64
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freqs []float64
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gzBank []*goertzel
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gzBank []*goertzel
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inA bool
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inA bool
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aFreq float64
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aFreq float64
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aAccumMs int
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aAccumMs int
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aStart time.Time
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aStart time.Time
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waitingB bool
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waitingB bool
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bFreq float64
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bFreq float64
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bAccumMs int
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bAccumMs int
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bStart time.Time
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bStart time.Time
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gapRemainMs int
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gapRemainMs int
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}
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}
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// newTwoToneDetector creates and initializes a twoToneDetector instance with the specified parameters.
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// It sets up a bank of Goertzel filters for detecting tones in the frequency range 300–3000 Hz (in 10 Hz steps).
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//
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// Parameters:
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//
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// fs - Sample rate in Hz.
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// winN - Window size (number of samples per analysis window).
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// hopN - Hop size (number of samples to advance per analysis).
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// ratioThresh- Threshold for the ratio used in tone detection.
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// rmsThresh - RMS threshold for signal energy.
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// minAms - Minimum duration of a detected tone in milliseconds.
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// minBms - Minimum duration of a break between tones in milliseconds.
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// gapMaxMs - Maximum allowed gap between tones in milliseconds.
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//
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// Returns:
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//
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// Pointer to an initialized twoToneDetector.
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func newTwoToneDetector(fs, winN, hopN int, ratioThresh, rmsThresh float64, minAms, minBms, gapMaxMs int) *twoToneDetector {
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func newTwoToneDetector(fs, winN, hopN int, ratioThresh, rmsThresh float64, minAms, minBms, gapMaxMs int) *twoToneDetector {
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// Frequency range: 300–3000 Hz, 10 Hz steps
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// Frequency range: 300–3000 Hz, 10 Hz steps
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freqs := make([]float64, 0)
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freqs := make([]float64, 0)
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for f := 300.0; f <= 3000.0; f += 10.0 {
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for f := 300.0; f <= 3000.0; f += 10.0 {
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freqs = append(freqs, f)
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freqs = append(freqs, f)
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}
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}
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gzBank := make([]*goertzel, len(freqs))
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gzBank := make([]*goertzel, len(freqs))
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for i, f := range freqs {
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for i, f := range freqs {
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gzBank[i] = newGoertzel(f, float64(fs), winN)
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gzBank[i] = newGoertzel(f, float64(fs), winN)
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}
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}
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return &twoToneDetector{
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return &twoToneDetector{
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fs: fs,
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fs: fs,
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winN: winN,
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winN: winN,
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hopN: hopN,
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hopN: hopN,
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ratioThresh: ratioThresh,
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ratioThresh: ratioThresh,
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rmsThresh: rmsThresh,
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rmsThresh: rmsThresh,
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minAms: minAms,
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minAms: minAms,
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minBms: minBms,
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minBms: minBms,
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gapMaxMs: gapMaxMs,
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gapMaxMs: gapMaxMs,
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freqs: freqs,
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freqs: freqs,
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gzBank: gzBank,
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gzBank: gzBank,
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}
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}
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}
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}
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// stepWindow processes a window of PCM audio samples to detect a two-tone event.
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// It applies a Hann window, computes the RMS, and searches for the strongest frequency.
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// The function tracks the presence and duration of two distinct tones (A and B) separated by a gap.
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// If both tones are detected with sufficient duration and within specified thresholds, it returns
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// an event string ("TWO_TONE_DETECTED") along with the frequencies and durations of tones A and B.
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// If detection criteria are not met, it resets the detector state and returns zero values.
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//
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// Parameters:
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//
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// pcms []int16 - Slice of PCM audio samples for the current window.
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// t0 time.Time - Timestamp corresponding to the start of the window.
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//
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// Returns:
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//
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// event string - Event name if two-tone detected, otherwise empty string.
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// aFreq float64 - Frequency of tone A (Hz).
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// aDur float64 - Duration of tone A (milliseconds).
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// bFreq float64 - Frequency of tone B (Hz).
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// bDur float64 - Duration of tone B (milliseconds).
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func (d *twoToneDetector) stepWindow(pcms []int16, t0 time.Time) (event string, aFreq, aDur, bFreq, bDur float64) {
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func (d *twoToneDetector) stepWindow(pcms []int16, t0 time.Time) (event string, aFreq, aDur, bFreq, bDur float64) {
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xi := pcmToFloat(pcms, d.winN)
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xi := pcmToFloat(pcms, d.winN)
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windowHann(xi)
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windowHann(xi)
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var total float64
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var total float64
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for _, v := range xi {
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for _, v := range xi {
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total += v * v
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total += v * v
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}
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}
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r := rmsPCM(pcms)
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r := rmsPCM(pcms)
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if r < d.rmsThresh {
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if r < d.rmsThresh {
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d.reset()
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d.reset()
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return "", 0, 0, 0, 0
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}
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// Find frequency with highest power
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bestIdx := -1
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bestPow := 0.0
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for i, gz := range d.gzBank {
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p := gz.Power(xi)
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if p > bestPow {
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bestPow = p
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bestIdx = i
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}
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}
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ratio := bestPow / (total + 1e-12)
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if ratio < d.ratioThresh {
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d.reset()
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return "", 0, 0, 0, 0
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}
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freq := d.freqs[bestIdx]
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hopDur := time.Millisecond * time.Duration(int(float64(d.hopN)*1000.0/float64(d.fs)))
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now := t0
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if !d.inA && !d.waitingB {
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// Looking for Tone A
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d.inA = true
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d.aFreq = freq
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d.aAccumMs = int(hopDur.Milliseconds())
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d.aStart = now
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} else if d.inA && !d.waitingB {
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// Confirming Tone A
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if math.Abs(freq-d.aFreq) <= 10.0 {
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d.aAccumMs += int(hopDur.Milliseconds())
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if d.aAccumMs >= d.minAms {
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d.inA = false
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d.waitingB = true
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d.gapRemainMs = d.gapMaxMs
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}
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} else {
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d.reset()
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}
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} else if d.waitingB {
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d.gapRemainMs -= int(hopDur.Milliseconds())
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if d.gapRemainMs <= 0 {
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d.reset()
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} else if math.Abs(freq-d.aFreq) > 10.0 {
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// Check for Tone B (different frequency)
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if d.bAccumMs == 0 {
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d.bFreq = freq
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d.bStart = now
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} else if math.Abs(freq-d.bFreq) > 10.0 {
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// Switched to a different frequency, reset B
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d.bFreq = freq
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d.bAccumMs = 0
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d.bStart = now
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}
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d.bAccumMs += int(hopDur.Milliseconds())
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if d.bAccumMs >= d.minBms {
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event = "TWO_TONE_DETECTED"
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return event, d.aFreq, float64(d.aAccumMs), d.bFreq, float64(d.bAccumMs)
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}
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}
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}
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return "", 0, 0, 0, 0
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return "", 0, 0, 0, 0
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}
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|
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// Find frequency with highest power
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bestIdx := -1
|
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bestPow := 0.0
|
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for i, gz := range d.gzBank {
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p := gz.Power(xi)
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if p > bestPow {
|
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bestPow = p
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bestIdx = i
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}
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}
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ratio := bestPow / (total + 1e-12)
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if ratio < d.ratioThresh {
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d.reset()
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return "", 0, 0, 0, 0
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}
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freq := d.freqs[bestIdx]
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hopDur := time.Millisecond * time.Duration(int(float64(d.hopN)*1000.0/float64(d.fs)))
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now := t0
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|
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if !d.inA && !d.waitingB {
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// Looking for Tone A
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d.inA = true
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d.aFreq = freq
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d.aAccumMs = int(hopDur.Milliseconds())
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d.aStart = now
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} else if d.inA && !d.waitingB {
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// Confirming Tone A
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if math.Abs(freq-d.aFreq) <= 10.0 {
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d.aAccumMs += int(hopDur.Milliseconds())
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if d.aAccumMs >= d.minAms {
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d.inA = false
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d.waitingB = true
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d.gapRemainMs = d.gapMaxMs
|
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}
|
|
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} else {
|
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d.reset()
|
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}
|
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} else if d.waitingB {
|
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d.gapRemainMs -= int(hopDur.Milliseconds())
|
|
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if d.gapRemainMs <= 0 {
|
|
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d.reset()
|
|
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} else if math.Abs(freq-d.aFreq) > 10.0 {
|
|
||||||
// Check for Tone B (different frequency)
|
|
||||||
if d.bAccumMs == 0 {
|
|
||||||
d.bFreq = freq
|
|
||||||
d.bStart = now
|
|
||||||
} else if math.Abs(freq-d.bFreq) > 10.0 {
|
|
||||||
// Switched to a different frequency, reset B
|
|
||||||
d.bFreq = freq
|
|
||||||
d.bAccumMs = 0
|
|
||||||
d.bStart = now
|
|
||||||
}
|
|
||||||
d.bAccumMs += int(hopDur.Milliseconds())
|
|
||||||
if d.bAccumMs >= d.minBms {
|
|
||||||
event = "TWO_TONE_DETECTED"
|
|
||||||
return event, d.aFreq, float64(d.aAccumMs), d.bFreq, float64(d.bAccumMs)
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
return "", 0, 0, 0, 0
|
|
||||||
}
|
}
|
||||||
|
|
||||||
|
// reset reinitializes all internal state fields of the twoToneDetector to their default values.
|
||||||
|
// This includes clearing detection flags, frequencies, accumulated durations, start times, and gap timers.
|
||||||
func (d *twoToneDetector) reset() {
|
func (d *twoToneDetector) reset() {
|
||||||
d.inA = false
|
d.inA = false
|
||||||
d.aFreq = 0
|
d.aFreq = 0
|
||||||
d.aAccumMs = 0
|
d.aAccumMs = 0
|
||||||
d.aStart = time.Time{}
|
d.aStart = time.Time{}
|
||||||
d.waitingB = false
|
d.waitingB = false
|
||||||
d.bFreq = 0
|
d.bFreq = 0
|
||||||
d.bAccumMs = 0
|
d.bAccumMs = 0
|
||||||
d.bStart = time.Time{}
|
d.bStart = time.Time{}
|
||||||
d.gapRemainMs = 0
|
d.gapRemainMs = 0
|
||||||
}
|
}
|
||||||
|
|
||||||
func main() {
|
func main() {
|
||||||
flag.Parse()
|
flag.Parse()
|
||||||
if *wavFile == "" {
|
if *wavFile == "" {
|
||||||
log.Fatal("WAV file path is required (use -wav flag)")
|
log.Fatal("WAV file path is required (use -wav flag)")
|
||||||
}
|
|
||||||
|
|
||||||
file, err := os.Open(*wavFile)
|
|
||||||
if err != nil {
|
|
||||||
log.Fatalf("Failed to open WAV file: %v", err)
|
|
||||||
}
|
|
||||||
defer file.Close()
|
|
||||||
|
|
||||||
decoder := wav.NewDecoder(file)
|
|
||||||
if !decoder.IsValidFile() {
|
|
||||||
log.Fatal("Invalid WAV file")
|
|
||||||
}
|
|
||||||
if decoder.Format().SampleRate != 8000 || decoder.Format().NumChannels != 1 {
|
|
||||||
log.Fatalf("WAV file must be mono 8kHz, got %d Hz, %d channels",
|
|
||||||
decoder.Format().SampleRate, decoder.Format().NumChannels)
|
|
||||||
}
|
|
||||||
|
|
||||||
const fs = 8000
|
|
||||||
winN := int(float64(fs) * float64(*winMs) / 1000.0)
|
|
||||||
hopN := int(float64(fs) * float64(*hopMs) / 1000.0)
|
|
||||||
if winN <= 0 || hopN <= 0 || hopN > winN {
|
|
||||||
log.Fatalf("Invalid window/hop: winN=%d, hopN=%d", winN, hopN)
|
|
||||||
}
|
|
||||||
|
|
||||||
det := newTwoToneDetector(fs, winN, hopN, *ratioThresh, *rmsThresh, *minAms, *minBms, *gapMaxMs)
|
|
||||||
|
|
||||||
buf := &audio.IntBuffer{
|
|
||||||
Format: &audio.Format{SampleRate: fs, NumChannels: 1},
|
|
||||||
Data: make([]int, 8192),
|
|
||||||
SourceBitDepth: 16,
|
|
||||||
}
|
|
||||||
sampleCount := 0
|
|
||||||
startTime := time.Now()
|
|
||||||
|
|
||||||
log.Println("Processing WAV file...")
|
|
||||||
for {
|
|
||||||
n, err := decoder.PCMBuffer(buf)
|
|
||||||
if err != nil || n == 0 || len(buf.Data) == 0 {
|
|
||||||
log.Printf("Finished processing %d samples (%.2f seconds)", sampleCount, float64(sampleCount)/float64(fs))
|
|
||||||
break
|
|
||||||
}
|
}
|
||||||
|
|
||||||
pcm := make([]int16, n)
|
file, err := os.Open(*wavFile)
|
||||||
for i, v := range buf.Data[:n] {
|
if err != nil {
|
||||||
pcm[i] = int16(v)
|
log.Fatalf("Failed to open WAV file: %v", err)
|
||||||
}
|
}
|
||||||
sampleCount += n
|
defer file.Close()
|
||||||
|
|
||||||
for offset := 0; offset <= len(pcm)-winN; offset += hopN {
|
decoder := wav.NewDecoder(file)
|
||||||
win := pcm[offset:min(offset+winN, len(pcm))]
|
if !decoder.IsValidFile() {
|
||||||
t := startTime.Add(time.Duration(sampleCount-len(pcm)+offset) * time.Second / time.Duration(fs))
|
log.Fatal("Invalid WAV file")
|
||||||
event, aFreq, aDur, bFreq, bDur := det.stepWindow(win, t)
|
}
|
||||||
if event != "" {
|
if decoder.Format().SampleRate != 8000 || decoder.Format().NumChannels != 1 {
|
||||||
fmt.Printf("Detected two-tone sequence:\n")
|
log.Fatalf("WAV file must be mono 8kHz, got %d Hz, %d channels",
|
||||||
fmt.Printf(" Tone A: %.1f Hz, duration %.0f ms\n", aFreq, aDur)
|
decoder.Format().SampleRate, decoder.Format().NumChannels)
|
||||||
fmt.Printf(" Tone B: %.1f Hz, duration %.0f ms\n", bFreq, bDur)
|
}
|
||||||
det.reset()
|
|
||||||
}
|
const fs = 8000
|
||||||
|
winN := int(float64(fs) * float64(*winMs) / 1000.0)
|
||||||
|
hopN := int(float64(fs) * float64(*hopMs) / 1000.0)
|
||||||
|
if winN <= 0 || hopN <= 0 || hopN > winN {
|
||||||
|
log.Fatalf("Invalid window/hop: winN=%d, hopN=%d", winN, hopN)
|
||||||
|
}
|
||||||
|
|
||||||
|
det := newTwoToneDetector(fs, winN, hopN, *ratioThresh, *rmsThresh, *minAms, *minBms, *gapMaxMs)
|
||||||
|
|
||||||
|
buf := &audio.IntBuffer{
|
||||||
|
Format: &audio.Format{SampleRate: fs, NumChannels: 1},
|
||||||
|
Data: make([]int, 8192),
|
||||||
|
SourceBitDepth: 16,
|
||||||
|
}
|
||||||
|
sampleCount := 0
|
||||||
|
startTime := time.Now()
|
||||||
|
|
||||||
|
log.Println("Processing WAV file...")
|
||||||
|
for {
|
||||||
|
n, err := decoder.PCMBuffer(buf)
|
||||||
|
if err != nil || n == 0 || len(buf.Data) == 0 {
|
||||||
|
log.Printf("Finished processing %d samples (%.2f seconds)", sampleCount, float64(sampleCount)/float64(fs))
|
||||||
|
break
|
||||||
|
}
|
||||||
|
|
||||||
|
pcm := make([]int16, n)
|
||||||
|
for i, v := range buf.Data[:n] {
|
||||||
|
pcm[i] = int16(v)
|
||||||
|
}
|
||||||
|
sampleCount += n
|
||||||
|
|
||||||
|
for offset := 0; offset <= len(pcm)-winN; offset += hopN {
|
||||||
|
win := pcm[offset:min(offset+winN, len(pcm))]
|
||||||
|
t := startTime.Add(time.Duration(sampleCount-len(pcm)+offset) * time.Second / time.Duration(fs))
|
||||||
|
event, aFreq, aDur, bFreq, bDur := det.stepWindow(win, t)
|
||||||
|
if event != "" {
|
||||||
|
fmt.Printf("Detected two-tone sequence:\n")
|
||||||
|
fmt.Printf(" Tone A: %.1f Hz, duration %.0f ms\n", aFreq, aDur)
|
||||||
|
fmt.Printf(" Tone B: %.1f Hz, duration %.0f ms\n", bFreq, bDur)
|
||||||
|
det.reset()
|
||||||
|
}
|
||||||
|
}
|
||||||
}
|
}
|
||||||
}
|
|
||||||
}
|
}
|
||||||
|
|
||||||
|
// min returns the smaller of two integer values a and b.
|
||||||
func min(a, b int) int {
|
func min(a, b int) int {
|
||||||
if a < b {
|
if a < b {
|
||||||
return a
|
return a
|
||||||
}
|
}
|
||||||
return b
|
return b
|
||||||
}
|
}
|
||||||
|
|||||||
Reference in New Issue
Block a user