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Create a new method to detect harmonic events
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Issue #471 Create a new method to detect harmonic events in a score array. Create new property in the HarmonicEvent class.
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@towsey
towsey committed Jun 12, 2021
1 parent 6c407af commit 3e14307
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Showing 2 changed files with 130 additions and 18 deletions.
4 changes: 4 additions & 0 deletions src/AudioAnalysisTools/Events/Types/HarmonicEvent.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,10 @@ namespace AudioAnalysisTools

public class HarmonicEvent : SpectralEvent
{
/// <summary>Gets or sets the interval or spacing between harmonics/formants.
/// </summary>
public double HarmonicInterval { get; set; }

public override void Draw(IImageProcessingContext graphics, EventRenderingOptions options)
{
// foreach (var track in tracks) {
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144 changes: 126 additions & 18 deletions src/AudioAnalysisTools/Harmonics/HarmonicParameters.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ namespace AnalysisPrograms.Recognizers.Base
{
using System;
using System.Collections.Generic;
using System.Linq;
using Acoustics.Shared;
using AudioAnalysisTools;
using AudioAnalysisTools.Events;
Expand Down Expand Up @@ -47,7 +48,7 @@ public static (List<EventCommon> SpectralEvents, List<Plot> DecibelPlots) GetCom

double[] decibelMaxArray;
double[] harmonicIntensityScores;
(spectralEvents, decibelMaxArray, harmonicIntensityScores) = HarmonicParameters.GetComponentsWithHarmonics(
(spectralEvents, decibelMaxArray, harmonicIntensityScores) = GetHarmonicEvents(
spectrogram,
hp.MinHertz.Value,
hp.MaxHertz.Value,
Expand All @@ -66,7 +67,7 @@ public static (List<EventCommon> SpectralEvents, List<Plot> DecibelPlots) GetCom
return (spectralEvents, plots);
}

public static (List<EventCommon> SpectralEvents, double[] AmplitudeArray, double[] HarmonicIntensityScores) GetComponentsWithHarmonics(
public static (List<EventCommon> SpectralEvents, double[] AmplitudeArray, double[] HarmonicIntensityScores) GetHarmonicEvents(
SpectrogramStandard spectrogram,
int minHz,
int maxHz,
Expand Down Expand Up @@ -97,7 +98,7 @@ public static (List<EventCommon> SpectralEvents, double[] AmplitudeArray, double
var results = CrossCorrelation.DetectHarmonicsInSpectrogramData(subMatrix, decibelThreshold);

// set up score arrays
double[] dBArray = results.Item1;
double[] dBArray = results.Item1; // this is not used currently.
double[] harmonicIntensityScores = results.Item2; //an array of formant intesnity
int[] maxIndexArray = results.Item3;

Expand Down Expand Up @@ -141,31 +142,138 @@ public static (List<EventCommon> SpectralEvents, double[] AmplitudeArray, double
}
}

//extract the events based on length and threshhold.
// Note: This method does NOT do prior smoothing of the score array.
var harmonicEvents = AcousticEvent.ConvertScoreArray2Events(
//extract the events based on length and threshhold.
// Note: This method does NOT do prior smoothing of the score array.
var harmonicEvents = ConvertScoreArray2Events(
spectrogram,
harmonicIntensityScores2,
dBArray,
maxIndexArray,
minDuration,
maxDuration,
minHz,
maxHz,
spectrogram.FramesPerSecond,
spectrogram.FBinWidth,
bandBinCount,
dctThreshold,
minDuration,
maxDuration,
segmentStartOffset);

//var spectralEvents = new List<HarmonicEvent>();
var spectralEvents = new List<EventCommon>();
return (harmonicEvents, dBArray, harmonicIntensityScores2);
}

/// <summary>
/// Finds harmonic events in an array harmonic scores.
/// NOTE: The score array is assumed to be temporal i.e. each element of the array is derived from a time frame.
/// The method uses the passed scoreThreshold in order to calculate a normalised score.
/// Max possible score := threshold * 5.
/// normalised score := score / maxPossibleScore.
/// </summary>
/// <param name="scores">the array of harmonic scores.</param>
/// <param name="maxIndexArray">the array of max index values derived from the DCT. Used to calculate the harmonic interval.</param>
/// <param name="minDuration">duration of event must exceed this to be a valid event.</param>
/// <param name="maxDuration">duration of event must be less than this to be a valid event.</param>
/// <param name="minHz">lower freq bound of the event.</param>
/// <param name="maxHz">upper freq bound of the event.</param>
/// <param name="scoreThreshold">threshold.</param>
/// <param name="segmentStartOffset">the time offset from segment start to the recording start.</param>
/// <returns>a list of acoustic events.</returns>
public static List<EventCommon> ConvertScoreArray2Events(
SpectrogramStandard spectrogram,
double[] scores,
double[] dBArray,
int[] maxIndexArray,
double minDuration,
double maxDuration,
int minHz,
int maxHz,
int bandBinCount,
double scoreThreshold,
TimeSpan segmentStartOffset)
{
double framesPerSec = spectrogram.FramesPerSecond;
double freqBinWidth = spectrogram.FBinWidth;

// create a unit converter
var converter = new UnitConverters(
segmentStartOffset: segmentStartOffset.TotalSeconds,
sampleRate: spectrogram.SampleRate,
frameSize: spectrogram.Configuration.WindowSize,
frameOverlap: spectrogram.Configuration.WindowOverlap);

// used this to calculate a normalised score between 0 - 1.0
double maxPossibleScore = 5 * scoreThreshold;
var scoreRange = new Interval<double>(0, maxPossibleScore);

bool isHit = false;
double frameOffset = 1 / framesPerSec;
int startFrame = 0;
int frameCount = scores.Length;

// add in temporary names to the events. These can be altered later.
foreach (var he in harmonicEvents)
var events = new List<EventCommon>();

// pass over all time frames
for (int i = 0; i < frameCount; i++)
{
var se = EventConverters.ConvertAcousticEventToSpectralEvent(he);
spectralEvents.Add(se);
se.Name = "Harmonics";
if (isHit == false && scores[i] >= scoreThreshold)
{
//start of an event
isHit = true;
startFrame = i + 2;
}
else // check for the end of an event
if (isHit && scores[i] <= scoreThreshold)
{
// this is end of an event, so initialise it
isHit = false;
double duration = (i - 1 - startFrame) * frameOffset;

if (duration < minDuration || duration > maxDuration)
{
//skip events with duration shorter than threshold
continue;
}

// obtain an average score and harmonic interval for the duration of the potential event.
double avScore = 0.0;
double avIndex = 0;
for (int n = startFrame; n <= i; n++)
{
avScore += scores[n];
avIndex += maxIndexArray[n];
}

// calculate average event score
int eventLength = i - startFrame;
avScore /= eventLength;
avIndex /= eventLength;
double freqBinGap = 2 * bandBinCount / avIndex;
double harmonicInterval = freqBinGap * freqBinWidth;

// calculate start and end time of this event relative to start of segment.
var eventStartWrtSegment = startFrame * frameOffset;
var eventEndWrtSegment = (i - 1) * frameOffset;

// Initialize the event.
var ev = new HarmonicEvent()
{
SegmentStartSeconds = segmentStartOffset.TotalSeconds,
SegmentDurationSeconds = frameCount * converter.SecondsPerFrameStep,
Name = "Stacked harmonics",
ResultStartSeconds = segmentStartOffset.TotalSeconds + eventStartWrtSegment,
EventStartSeconds = segmentStartOffset.TotalSeconds + eventStartWrtSegment,
EventEndSeconds = segmentStartOffset.TotalSeconds + eventEndWrtSegment,
LowFrequencyHertz = minHz,
HighFrequencyHertz = maxHz,
Score = avScore,
ScoreRange = scoreRange,
HarmonicInterval = harmonicInterval,
//DecibelDetectionThreshold,
};

events.Add(ev);
}
}

return (spectralEvents, dBArray, harmonicIntensityScores2);
return events;
}
}
}

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