add dB support

swharden · swharden · commit ed99af89e188 · 2020-06-06T16:56:44.000-04:00
diff --git a/src/Spectrogram.MicrophoneDemo/Form1.Designer.cs b/src/Spectrogram.MicrophoneDemo/Form1.Designer.cs
diff --git a/src/Spectrogram.MicrophoneDemo/Form1.cs b/src/Spectrogram.MicrophoneDemo/Form1.cs
@@ -65,12 +65,14 @@ private void timer1_Tick(object sender, EventArgs e)
             double[] newAudio = listener.GetNewAudio();
             spec.Add(newAudio);
 
+            double multiplier = tbBrightness.Value / 20.0;
+
             if (spec.FftsToProcess > 0)
             {
                 Stopwatch sw = Stopwatch.StartNew();
                 spec.Process();
                 spec.TrimWidth(pictureBox1.Width);
-                Bitmap bmp = spec.GetBitmap();
+                Bitmap bmp = spec.GetBitmap(multiplier, cbDecibels.Checked);
                 sw.Stop();
                 pictureBox1.Image?.Dispose();
                 pictureBox1.Image = bmp;
diff --git a/src/Spectrogram.MicrophoneDemo/Listener.cs b/src/Spectrogram.MicrophoneDemo/Listener.cs
@@ -46,18 +46,24 @@ private void OnNewAudioData(object sender, NAudio.Wave.WaveInEventArgs args)
                 buffer[i] = BitConverter.ToInt16(args.Buffer, i * bytesPerSample);
                 peak = Math.Max(peak, buffer[i]);
             }
-            audio.AddRange(buffer);
+            lock (audio)
+            {
+                audio.AddRange(buffer);
+            }
             AmplitudeFrac = peak / (1 << 15);
             TotalSamples += newSampleCount;
         }
 
         public double[] GetNewAudio()
         {
-            double[] values = new double[audio.Count];
-            for (int i = 0; i < values.Length; i++)
-                values[i] = audio[i];
-            audio.RemoveRange(0, values.Length);
-            return values;
+            lock (audio)
+            {
+                double[] values = new double[audio.Count];
+                for (int i = 0; i < values.Length; i++)
+                    values[i] = audio[i];
+                audio.RemoveRange(0, values.Length);
+                return values;
+            }
         }
     }
 }
diff --git a/src/Spectrogram/Spectrogram.cs b/src/Spectrogram/Spectrogram.cs
@@ -88,7 +88,7 @@ public void Process()
             newAudio.RemoveRange(0, newFftCount * settings.StepSize);
         }
 
-        public Bitmap GetBitmap(double multiplier = 1)
+        public Bitmap GetBitmap(double multiplier = 1, bool dB = false)
         {
             if (Width == 0)
                 return null;
@@ -105,7 +105,10 @@ public Bitmap GetBitmap(double multiplier = 1)
             {
                 for (int row = 0; row < Height; row++)
                 {
-                    double value = ffts[col][row] * multiplier;
+                    double value = ffts[col][row];
+                    if (dB)
+                        value = 20 * Math.Log10(value + 1);
+                    value *= multiplier;
                     value = Math.Min(value, 255);
                     int bytePosition = (Height - 1 - row) * stride + col;
                     bytes[bytePosition] = (byte)value;

Original file line number	Diff line number	Diff line change
`@@ -46,18 +46,24 @@ private void OnNewAudioData(object sender, NAudio.Wave.WaveInEventArgs args)`
`46`	`46`	`buffer[i] = BitConverter.ToInt16(args.Buffer, i * bytesPerSample);`
`47`	`47`	`peak = Math.Max(peak, buffer[i]);`
`48`	`48`	`}`
`49`		`- audio.AddRange(buffer);`
	`49`	`+ lock (audio)`
	`50`	`+ {`
	`51`	`+ audio.AddRange(buffer);`
	`52`	`+ }`
`50`	`53`	`AmplitudeFrac = peak / (1 << 15);`
`51`	`54`	`TotalSamples += newSampleCount;`
`52`	`55`	`}`
`53`	`56`
`54`	`57`	`public double[] GetNewAudio()`
`55`	`58`	`{`
`56`		`- double[] values = new double[audio.Count];`
`57`		`- for (int i = 0; i < values.Length; i++)`
`58`		`- values[i] = audio[i];`
`59`		`- audio.RemoveRange(0, values.Length);`
`60`		`- return values;`
	`59`	`+ lock (audio)`
	`60`	`+ {`
	`61`	`+ double[] values = new double[audio.Count];`
	`62`	`+ for (int i = 0; i < values.Length; i++)`
	`63`	`+ values[i] = audio[i];`
	`64`	`+ audio.RemoveRange(0, values.Length);`
	`65`	`+ return values;`
	`66`	`+ }`
`61`	`67`	`}`
`62`	`68`	`}`
`63`	`69`	`}`
Original file line number	Diff line number	Diff line change
`@@ -88,7 +88,7 @@ public void Process()`
`88`	`88`	`newAudio.RemoveRange(0, newFftCount * settings.StepSize);`
`89`	`89`	`}`
`90`	`90`
`91`		`- public Bitmap GetBitmap(double multiplier = 1)`
	`91`	`+ public Bitmap GetBitmap(double multiplier = 1, bool dB = false)`
`92`	`92`	`{`
`93`	`93`	`if (Width == 0)`
`94`	`94`	`return null;`
`@@ -105,7 +105,10 @@ public Bitmap GetBitmap(double multiplier = 1)`
`105`	`105`	`{`
`106`	`106`	`for (int row = 0; row < Height; row++)`
`107`	`107`	`{`
`108`		`- double value = ffts[col][row] * multiplier;`
	`108`	`+ double value = ffts[col][row];`
	`109`	`+ if (dB)`
	`110`	`+ value = 20 * Math.Log10(value + 1);`
	`111`	`+ value *= multiplier;`
`109`	`112`	`value = Math.Min(value, 255);`
`110`	`113`	`int bytePosition = (Height - 1 - row) * stride + col;`
`111`	`114`	`bytes[bytePosition] = (byte)value;`