add NAudio WAV reading demo as a test

#21

Author: swharden

data/asehgal-original.wav

@@ -8,6 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="MP3Sharp" Version="1.0.5" />
+    <PackageReference Include="NAudio" Version="1.10.0" />
     <PackageReference Include="nunit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.15.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />

src/Spectrogram.Tests/Spectrogram.Tests.csproj

@@ -0,0 +1,43 @@
+using NAudio.Wave;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Spectrogram.Tests
+{
+    class WavUsingLibrary
+    {
+        [Test]
+        public void Test_WavFile_ReadASehgal()
+        {
+            // READ THE WAV FILE WITH NAUDIO
+            double[] audio;
+            int sampleRate;
+            string wavFilePath = "../../../../../data/asehgal-original.wav";
+
+            using (var audioFileReader = new AudioFileReader(wavFilePath))
+            {
+                sampleRate = audioFileReader.WaveFormat.SampleRate;
+                var wholeFile = new List<float>((int)(audioFileReader.Length / 4));
+                var readBuffer = new float[audioFileReader.WaveFormat.SampleRate * audioFileReader.WaveFormat.Channels];
+                int samplesRead = 0;
+                while ((samplesRead = audioFileReader.Read(readBuffer, 0, readBuffer.Length)) > 0)
+                    wholeFile.AddRange(readBuffer.Take(samplesRead));
+                audio = Array.ConvertAll(wholeFile.ToArray(), x => (double)x);
+            }
+
+            // TEST VALUES ARE WHAT WE EXPECT
+            double lengthSec = (double)audio.Length / sampleRate;
+            Assert.AreEqual(40_000, sampleRate);
+            Assert.AreEqual(40, lengthSec, .01);
+
+            // CREATE THE SPECTROGRAM
+            int fftSize = 8192;
+            var spec = new Spectrogram(sampleRate, fftSize, stepSize: 4_000, maxFreq: 2_000);
+            spec.Add(audio);
+            spec.SaveImage("asehgal.png", intensity: 10_000, dB: true);
+        }
+    }
+}