Fix production of Octave spectrogram

Issue #332

src/AnalysisPrograms/SpectrogramGenerator/SpectrogramGenerator.Core.cs

@@ -75,7 +75,7 @@ public static AudioToSonogramResult GenerateSpectrogramImages(
             // EXTRACT ENVELOPE and SPECTROGRAM FROM RECORDING SEGMENT
             var dspOutput1 = DSP_Frames.ExtractEnvelopeAndFfts(recordingSegment, frameSize, frameStep);
 
-            // This constructor initalises default values for Melscale and Mfcc spectrograms and other parameters.
+            // This constructor initializes default values for Melscale and Mfcc spectrograms and other parameters.
             var sonoConfig = new SonogramConfig()
             {
                 epsilon = recordingSegment.Epsilon,
@@ -211,9 +211,29 @@ public static AudioToSonogramResult GenerateSpectrogramImages(
             // IMAGE 8) Octave-frequency scale Spectrogram
             if (@do.Contains(OctaveScaleSpectrogram))
             {
+                //Create new config because calling the octave spectrogram changes it.
+                var octaveConfig = new SonogramConfig()
+                {
+                    epsilon = recordingSegment.Epsilon,
+                    SampleRate = sampleRate,
+                    WindowSize = frameSize,
+                    WindowStep = frameStep,
+                    WindowOverlap = frameOverlap,
+                    WindowPower = dspOutput1.WindowPower,
+                    Duration = recordingSegment.Duration,
+                    NoiseReductionType = NoiseReductionType.Standard,
+                    NoiseReductionParameter = bgNoiseThreshold,
+                };
+
+                // Here are some of the possible octave frequency scales.
+                //var freqScale = new FrequencyScale(FreqScaleType.LinearOctaveStandard);
+                //var freqScale = new FrequencyScale(FreqScaleType.OctaveDataReduction);
+                //var freqScale = new FrequencyScale(FreqScaleType.Linear62OctaveTones31Nyquist11025);
+                //var freqScale = new FrequencyScale(FreqScaleType.Linear125OctaveTones32Nyquist11025);
+
                 images.Add(
                     OctaveScaleSpectrogram,
-                    GetOctaveScaleSpectrogram(sonoConfig, recordingSegment, sourceRecordingName));
+                    GetOctaveScaleSpectrogram(octaveConfig, FreqScaleType.Linear62OctaveTones31Nyquist11025, recordingSegment, sourceRecordingName));
             }
 
             // IMAGE 9) AmplitudeSpectrogram_LocalContrastNormalization
@@ -403,24 +423,34 @@ public static Image<Rgb24> GetCepstralSpectrogram(
         }
 
         public static Image<Rgb24> GetOctaveScaleSpectrogram(
-        SonogramConfig sonoConfig,
+        SonogramConfig sgConfig,
+        FreqScaleType fst,
         AudioRecording recording,
         string sourceRecordingName)
         {
+            var freqScale = new FrequencyScale(fst)
+            {
+                WindowStep = 512,
+            };
+
+            // ensure that the freq scale and the config are consistent.
+            sgConfig.WindowSize = freqScale.WindowSize;
+            freqScale.WindowStep = sgConfig.WindowStep;
+            sgConfig.WindowOverlap = SonogramConfig.CalculateFrameOverlap(freqScale.WindowSize, freqScale.WindowStep);
+
             // TODO at present noise reduction type must be set = Standard.
-            sonoConfig.NoiseReductionType = NoiseReductionType.Standard;
-            sonoConfig.NoiseReductionParameter = 3.0;
+            sgConfig.NoiseReductionType = NoiseReductionType.Standard;
+            sgConfig.NoiseReductionParameter = 3.0;
 
-            /// ########################################################################TODO TODO need to init as AmplitudeSpectrogram and then use constructor at Line 25 of SpectrogramOctaveScale..
-            var octaveScaleGram = new SpectrogramOctaveScale(sonoConfig, recording.WavReader);
+            var octaveScaleGram = new SpectrogramOctaveScale(sgConfig, freqScale, recording.WavReader);
             var image = octaveScaleGram.GetImage();
             var titleBar = BaseSonogram.DrawTitleBarOfGrayScaleSpectrogram(
                     "OCTAVE-SCALE SPECTROGRAM " + sourceRecordingName,
                     image.Width,
                     ImageTags[CepstralSpectrogram]);
             var startTime = TimeSpan.Zero;
             var xAxisTicInterval = TimeSpan.FromSeconds(1);
-            TimeSpan xAxisPixelDuration = TimeSpan.FromSeconds(sonoConfig.WindowStep / (double)sonoConfig.SampleRate);
+            TimeSpan xAxisPixelDuration = TimeSpan.FromSeconds(sgConfig.WindowStep / (double)sgConfig.SampleRate);
             var labelInterval = TimeSpan.FromSeconds(5);
             image = BaseSonogram.FrameSonogram(image, titleBar, startTime, xAxisTicInterval, xAxisPixelDuration, labelInterval);
             return image;

src/AudioAnalysisTools/DSP/OctaveFreqScale.cs

@@ -11,19 +11,17 @@ namespace AudioAnalysisTools.DSP
 
     public static class OctaveFreqScale
     {
-        /// IMPORTANT NOTE: If you are converting Herz scale from LINEAR to OCTAVE, this conversion MUST be done BEFORE noise reduction
         /// <summary>
         /// CONSTRUCTION OF Frequency Scales
+        /// IMPORTANT NOTE: If you are converting Herz scale from LINEAR to OCTAVE, this conversion MUST be done BEFORE noise reduction
         /// WARNING!: Changing the constants for the octave scales will have undefined effects.
         ///           The options below have been debugged to give what is required.
         ///           However other values have not been debugged - so user should check the output to ensure it is what is required.
+        /// NOTE: octaveDivisions = the number of fractional Hz steps within one octave. Piano octave contains 12 steps per octave.
         /// </summary>
         public static void GetOctaveScale(FrequencyScale scale)
         {
             int sr, frameSize;
-
-            // NOTE: octaveDivisions = the number of fractional Hz steps within one octave. Piano octave contains 12 steps per octave.
-
             var fst = scale.ScaleType;
 
             switch (fst)
@@ -43,7 +41,7 @@ public static void GetOctaveScale(FrequencyScale scale)
 
                 case FreqScaleType.Linear62OctaveTones31Nyquist11025:
                     sr = 22050;
-                    frameSize = 8192;
+                    frameSize = 2048;
                     scale.LinearBound = 62;
 
                     // tone steps within one octave. Note: piano = 12 steps per octave.
@@ -53,13 +51,13 @@ public static void GetOctaveScale(FrequencyScale scale)
                 case FreqScaleType.Linear125OctaveTones32Nyquist11025:
                     // constants required for split linear-octave scale when sr = 22050
                     sr = 22050;
-                    frameSize = 8192;
+                    frameSize = 2048;
                     scale.LinearBound = 125;
                     scale.ToneCount = 32; // tone steps within one octave. Note: piano = 12 steps per octave.
                     break;
 
                 case FreqScaleType.Octaves24Nyquist32000:
-                    //// constants required for full octave scale when sr = 64000
+                    // constants required for full octave scale when sr = 64000
                     sr = 64000;
                     frameSize = 16384;
                     scale.LinearBound = 15;