Rework Ocatve scale when calculating acoustic indices

Issue #332 Previously calculated an octave scale that was once used for a high SR marine recording. Now implement an octave scale that is used for spectral data reduction. This will be used subsequently for content description.

src/AudioAnalysisTools/Indices/IndexCalculate.cs

@@ -156,20 +156,18 @@ public static IndexCalculateResult Analysis(
             //dspOutput1.NyquistBin = dspOutput1.AmplitudeSpectrogram.GetLength(1) - 1;
             //dspOutput1.FreqBinWidth = sampleRate / (double)dspOutput1.AmplitudeSpectrogram.GetLength(1) / 2;
 
-            // Linear or Octave or Mel frequency scale? Set Linear as default.
+            // Linear or Octave or Mel frequency scale?
+            // Set Linear as default.
             var freqScale = new FrequencyScale(nyquist: nyquist, frameSize: frameSize, hertzGridInterval: 1000);
             var freqScaleType = config.FrequencyScale;
-            bool octaveScale = freqScaleType == FreqScaleType.OctaveStandard || freqScaleType == FreqScaleType.OctaveCustom;
+            bool octaveScale = freqScaleType == FreqScaleType.OctaveDataReduction;
             bool melScale = freqScaleType == FreqScaleType.Mel;
             if (octaveScale)
             {
-                throw new Exception("Octave scales not currently implemented.");
-
-                //TODO This is to be worked on.
-                // only allow one octave scale at the moment - for Jasco marine recordings.
-                // ASSUME fixed Occtave scale - USEFUL ONLY FOR JASCO 64000sr MARINE RECORDINGS
-                // If you wish to use other octave scale types then need to put in the config file and and set up recovery here.
-                freqScale = new FrequencyScale(freqScaleType);
+                // Only allow one octave scale at the moment, OctaveDataReduction.
+                // This is used to produced a reduced set of indices for content recognition.
+                // TODO: Much work required to generalise this for other Octave scales. Need to put scale type in the config file and and set up recovery here.
+                freqScale = new FrequencyScale(FreqScaleType.OctaveDataReduction);
 
                 // Recalculate the spectrogram according to octave scale. This option works only when have high SR recordings.
                 dspOutput1.AmplitudeSpectrogram = OctaveFreqScale.AmplitudeSpectra(
@@ -316,13 +314,8 @@ public static IndexCalculateResult Analysis(
             if (octaveScale)
             {
                 // the above frequency bin bounds do not apply with octave scale. Need to recalculate them suitable for Octave scale recording.
-                lowFreqBound = freqScale.LinearBound;
                 lowerBinBound = freqScale.GetBinIdForHerzValue(lowFreqBound);
-
-                midFreqBound = 8000; // This value appears suitable for Jasco Marine recordings. Not much happens above 8kHz.
-
-                //middleBinBound = freqScale.GetBinIdForHerzValue(midFreqBound);
-                middleBinBound = freqScale.GetBinIdInReducedSpectrogramForHerzValue(midFreqBound);
+                middleBinBound = freqScale.GetBinIdForHerzValue(midFreqBound);
                 midBandBinCount = middleBinBound - lowerBinBound + 1;
             }
 

src/AudioAnalysisTools/Indices/IndexCalculateConfig.cs

@@ -150,7 +150,13 @@ public FreqScaleType FrequencyScale
                 switch (value)
                 {
                     case FreqScaleType.Linear:
-                    case FreqScaleType.OctaveStandard:
+                    //case FreqScaleType.OctaveStandard:
+                    //    this.frequencyScale = value;
+                    //    break;
+                    //case FreqScaleType.OctaveCustom:
+                    //    this.frequencyScale = value;
+                    //    break;
+                    case FreqScaleType.OctaveDataReduction:
                         this.frequencyScale = value;
                         break;
                     default:

tests/Acoustics.Test/AudioAnalysisTools/Indices/IndexCalculateTest.cs

@@ -279,14 +279,14 @@ public void TestOfSpectralIndices_ICD20()
         }
 
         /// <summary>
-        /// Test index calculation when the Hertz FreqScaleType = Octave.
-        /// Only test the BGN spectral index as reasonable to assume that the rest will work if ACI works.
+        /// Test index calculation when the Hertz FreqScaleType = OctaveDataReduction.
+        /// Only test the BGN and CVR spectral index as reasonable to assume that the rest will work if these work.
         /// </summary>
         [TestMethod]
-        public void TestOfSpectralIndices_Octave()
+        public void TestOfSpectralIndices_OctaveDataReduction()
         {
             // create a two-minute artificial recording containing five harmonics.
-            int sampleRate = 64000;
+            int sampleRate = 22050;
             double duration = 120; // signal duration in seconds
             int[] harmonics = { 500, 1000, 2000, 4000, 8000 };
             var recording = DspFilters.GenerateTestRecording(sampleRate, duration, harmonics, WaveType.Sine);
@@ -309,15 +309,10 @@ public void TestOfSpectralIndices_Octave()
 
             // CHANGE CONFIG PARAMETERS HERE IF REQUIRED
             var indexCalculateConfig = ConfigFile.Deserialize<AcousticIndices.AcousticIndicesConfig>(configFile);
-            indexCalculateConfig.FrequencyScale = FreqScaleType.OctaveStandard;
-            int nyquist = sampleRate / 2;
-            int frameSize = 512;
-            int linearBound = 1000;
-            int octaveToneCount = 1; // this set automatically
-            int gridInterval = 1000;
-            var freqScale = new FrequencyScale(FreqScaleType.OctaveStandard, nyquist, frameSize, linearBound, octaveToneCount, gridInterval);
+            indexCalculateConfig.FrameLength = 512;
 
-            indexCalculateConfig.FrameLength = freqScale.WindowSize;
+            //WARNING: Currently only one octave scale is available.
+            indexCalculateConfig.FrequencyScale = FreqScaleType.OctaveDataReduction;
 
             var results = IndexCalculate.Analysis(
                 subsegmentRecording,
@@ -336,14 +331,16 @@ public void TestOfSpectralIndices_Octave()
             image.Save(outputImagePath1);
 
             // TEST the BGN SPECTRAL INDEX
-            Assert.AreEqual(256, spectralIndices.BGN.Length);
+            Assert.AreEqual(20, spectralIndices.BGN.Length);
 
-            //Binary.Serialize(expectedSpectrumFile, spectralIndices.BGN);
-            var expectedVector = Binary.Deserialize<double[]>(PathHelper.ResolveAsset("Indices", "BGN_OctaveScale.bin"));
+            var expectedSpectrumFile1 = PathHelper.ResolveAsset("Indices", "BGN_OctaveScale.bin");
+            //Binary.Serialize(expectedSpectrumFile1, spectralIndices.BGN);
+            var expectedVector = Binary.Deserialize<double[]>(expectedSpectrumFile1);
             CollectionAssert.That.AreEqual(expectedVector, spectralIndices.BGN, AllowedDelta);
 
-            //Binary.Serialize(expectedSpectrumFile, spectralIndices.CVR);
-            expectedVector = Binary.Deserialize<double[]>(PathHelper.ResolveAsset("Indices", "CVR_OctaveScale.bin"));
+            var expectedSpectrumFile2 = PathHelper.ResolveAsset("Indices", "CVR_OctaveScale.bin");
+            //Binary.Serialize(expectedSpectrumFile2, spectralIndices.CVR);
+            expectedVector = Binary.Deserialize<double[]>(expectedSpectrumFile2);
             CollectionAssert.That.AreEqual(expectedVector, spectralIndices.CVR, AllowedDelta);
         }
     }