Open source C# code to present wave form?

Question

Is there any open source C# code or library to present a graphical waveform given a byte array?

Answer 1

This is as open source as it gets:

public static void DrawNormalizedAudio(ref float[] data, PictureBox pb,     Color color) {     Bitmap bmp;     if (pb.Image == null)     {         bmp = new Bitmap(pb.Width, pb.Height);     }     else     {         bmp = (Bitmap)pb.Image;     }      int BORDER_WIDTH = 5;     int width = bmp.Width - (2 * BORDER_WIDTH);     int height = bmp.Height - (2 * BORDER_WIDTH);      using (Graphics g = Graphics.FromImage(bmp))     {         g.Clear(Color.Black);         Pen pen = new Pen(color);         int size = data.Length;         for (int iPixel = 0; iPixel < width; iPixel++)         {             // determine start and end points within WAV             int start = (int)((float)iPixel * ((float)size / (float)width));             int end = (int)((float)(iPixel + 1) * ((float)size / (float)width));             float min = float.MaxValue;             float max = float.MinValue;             for (int i = start; i < end; i++)             {                 float val = data[i];                 min = val < min ? val : min;                 max = val > max ? val : max;             }             int yMax = BORDER_WIDTH + height - (int)((max + 1) * .5 * height);             int yMin = BORDER_WIDTH + height - (int)((min + 1) * .5 * height);             g.DrawLine(pen, iPixel + BORDER_WIDTH, yMax,                  iPixel + BORDER_WIDTH, yMin);         }     }     pb.Image = bmp; } 

This function will produce something like this:

This takes an array of samples in floating-point format (where all sample values range from -1 to +1). If your original data is actually in the form of a byte[] array, you'll have to do a little bit of work to convert it to float[]. Let me know if you need that, too.

Update: since the question technically asked for something to render a byte array, here are a couple of helper methods:

public float[] FloatArrayFromStream(System.IO.MemoryStream stream) {     return FloatArrayFromByteArray(stream.GetBuffer()); }  public float[] FloatArrayFromByteArray(byte[] input) {     float[] output = new float[input.Length / 4];     for (int i = 0; i < output.Length; i++)     {         output[i] = BitConverter.ToSingle(input, i * 4);     }     return output; } 

Update 2: I forgot there's a better way to do this:

public float[] FloatArrayFromByteArray(byte[] input) {     float[] output = new float[input.Length / 4];     Buffer.BlockCopy(input, 0, output, 0, input.Length);     return output; } 

I'm just so in love with for loops, I guess.

Answer 2

I modified MusiGenesis's solution a little bit. This gave me a much better result, especially with house music :)

public static Bitmap DrawNormalizedAudio(List<float> data, Color foreColor, Color backColor, Size imageSize) {     Bitmap bmp = new Bitmap(imageSize.Width, imageSize.Height);      int BORDER_WIDTH = 0;     float width = bmp.Width - (2 * BORDER_WIDTH);     float height = bmp.Height - (2 * BORDER_WIDTH);      using (Graphics g = Graphics.FromImage(bmp))     {         g.Clear(backColor);         Pen pen = new Pen(foreColor);         float size = data.Count;         for (float iPixel = 0; iPixel < width; iPixel += 1)         {             // determine start and end points within WAV             int start = (int)(iPixel * (size / width));             int end = (int)((iPixel + 1) * (size / width));             if (end > data.Count)                 end = data.Count;              float posAvg, negAvg;             averages(data, start, end, out posAvg, out negAvg);              float yMax = BORDER_WIDTH + height - ((posAvg + 1) * .5f * height);             float yMin = BORDER_WIDTH + height - ((negAvg + 1) * .5f * height);              g.DrawLine(pen, iPixel + BORDER_WIDTH, yMax, iPixel + BORDER_WIDTH, yMin);         }     }      return bmp; }   private static void averages(List<float> data, int startIndex, int endIndex, out float posAvg, out float negAvg) {     posAvg = 0.0f;     negAvg = 0.0f;      int posCount = 0, negCount = 0;      for (int i = startIndex; i < endIndex; i++)     {         if (data[i] > 0)         {             posCount++;             posAvg += data[i];         }         else         {             negCount++;             negAvg += data[i];         }     }      posAvg /= posCount;     negAvg /= negCount; }