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Sound visualizer in C#

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4.90/5 (58 votes)
15 Aug 2007GPL3 433.6K   39.7K   228   73
Simple sound sampler with visualization
Screenshot - SoundViewer.jpg

Introduction

This project demonstrates the use of the Fast Fourier Transform and Windows GDI to produce near real-time visualizations of the time and frequency domains of sound.

Background

While looking for information on signal processing for a robotics project, it became apparent that examples written in C# were hard to find. This led me to create some of my own classes, which I have provided here for this demonstration.

Using the Code

Audio input for this demonstration is provided by the Wave classes developed by Ianier Munoz. Wave samples are further processed using the AudioFrame class.

C#
class AudioFrame
{
    private Bitmap _canvasTimeDomain;
    private Bitmap _canvasFrequencyDomain;
    private double[] _waveLeft;
    private double[] _waveRight;
    private double[] _fftLeft;
    private double[] _fftRight;
    private SignalGenerator _signalGenerator;
    private bool _isTest = false;
    public AudioFrame(bool isTest)
    {
        _isTest = isTest;
    }

    /// <summary>
    /// Process 16 bit sample
    /// </summary>
    /// <param name="wave"></param>
    public void Process(ref byte[] wave)
    {
        _waveLeft = new double[wave.Length / 4];
        _waveRight = new double[wave.Length / 4];
        if (_isTest == false)
        {
            // Split out channels from sample
            int h = 0;
            for (int i = 0; i < wave.Length; i += 4)
            {
                _waveLeft[h] = (double)BitConverter.ToInt16(wave, i);
                _waveRight[h] = (double)BitConverter.ToInt16(wave, i + 2);
                h++;
            }
        }
        else
        {
            // Generate artificial sample for testing
            _signalGenerator = new SignalGenerator();
            _signalGenerator.SetWaveform("Sine");
            _signalGenerator.SetSamplingRate(44100);
            _signalGenerator.SetSamples(16384);
            _signalGenerator.SetFrequency(5000);
            _signalGenerator.SetAmplitude(32768);
            _waveLeft = _signalGenerator.GenerateSignal();
            _waveRight = _signalGenerator.GenerateSignal();
        }
        // Generate frequency domain data in decibels
        _fftLeft = FourierTransform.FFTDb(ref _waveLeft);
        _fftRight = FourierTransform.FFTDb(ref _waveRight);
    }

    /// <summary>
    /// Render time domain to PictureBox
    /// </summary>
    /// <param name="pictureBox"></param>
    public void RenderTimeDomain(ref PictureBox pictureBox)
    {
        // Set up for drawing
        _canvasTimeDomain = new Bitmap(pictureBox.Width, pictureBox.Height);
        Graphics offScreenDC = Graphics.FromImage(_canvasTimeDomain);
        SolidBrush brush = new System.Drawing.SolidBrush
                    (Color.FromArgb(0, 0, 0));
        Pen pen = new System.Drawing.Pen(Color.WhiteSmoke);
        // Determine channel boundaries
        int width = _canvasTimeDomain.Width;
        int center = _canvasTimeDomain.Height / 2;
        int height = _canvasTimeDomain.Height;
        offScreenDC.DrawLine(pen, 0, center, width, center);
        int leftLeft = 0;
        int leftTop = 0;
        int leftRight = width;
        int leftBottom = center - 1;
        int rightLeft = 0;
        int rightTop = center + 1;
        int rightRight = width;
        int rightBottom = height;
        // Draw left channel
        double yCenterLeft = (leftBottom - leftTop) / 2;
        double yScaleLeft = 0.5 * (leftBottom - leftTop) / 32768;  
            // a 16 bit sample has values from -32768 to 32767
        int xPrevLeft = 0, yPrevLeft = 0;
        for (int xAxis = leftLeft; xAxis < leftRight; xAxis++)
        {
            int yAxis = (int)(yCenterLeft + (_waveLeft[_waveLeft.Length / 
                (leftRight - leftLeft) * xAxis] * yScaleLeft));
            if (xAxis == 0)
            {
                xPrevLeft = 0;
                yPrevLeft = yAxis;
            }
            else
            {
                pen.Color = Color.LimeGreen;
                offScreenDC.DrawLine(pen, xPrevLeft, yPrevLeft, xAxis,yAxis);
                xPrevLeft = xAxis;
                yPrevLeft = yAxis;
            }
        }
        // Draw right channel
        int xCenterRight = rightTop + ((rightBottom - rightTop) / 2);
        double yScaleRight = 0.5 * (rightBottom - rightTop) / 32768;  
            // a 16 bit sample has values from -32768 to 32767
        int xPrevRight = 0, yPrevRight = 0;
        for (int xAxis = rightLeft; xAxis < rightRight; xAxis++)
        {
            int yAxis = (int)(xCenterRight + (_waveRight[_waveRight.Length / 
            (rightRight - rightLeft) * xAxis] * yScaleRight));
            if (xAxis == 0)
            {
                xPrevRight = 0;
                yPrevRight = yAxis;
            }
            else
            {
                pen.Color = Color.LimeGreen;
                offScreenDC.DrawLine
                (pen, xPrevRight, yPrevRight, xAxis, yAxis);
                xPrevRight = xAxis;
                yPrevRight = yAxis;
            }
        }
        // Clean up
        pictureBox.Image = _canvasTimeDomain;
        offScreenDC.Dispose();
    }

    /// <summary>
    /// Render frequency domain to PictureBox
    /// </summary>
    /// <param name="pictureBox"></param>
    public void RenderFrequencyDomain(ref PictureBox pictureBox)
    {
        // Set up for drawing
        _canvasFrequencyDomain = new Bitmap
                (pictureBox.Width, pictureBox.Height);
        Graphics offScreenDC = Graphics.FromImage(_canvasFrequencyDomain);
        SolidBrush brush = new System.Drawing.SolidBrush
                    (Color.FromArgb(0, 0, 0));
        Pen pen = new System.Drawing.Pen(Color.WhiteSmoke);
        // Determine channel boundaries
        int width = _canvasFrequencyDomain.Width;
        int center = _canvasFrequencyDomain.Height / 2;
        int height = _canvasFrequencyDomain.Height;
        offScreenDC.DrawLine(pen, 0, center, width, center);
        int leftLeft = 0;
        int leftTop = 0;
        int leftRight = width;
        int leftBottom = center - 1;
        int rightLeft = 0;
        int rightTop = center + 1;
        int rightRight = width;
        int rightBottom = height;
        // Draw left channel
        for (int xAxis = leftLeft; xAxis < leftRight; xAxis++)
        {
            double amplitude = (int)_fftLeft[(int)(((double)(_fftLeft.Length)
                         / (double)(width)) * xAxis)];
            if (amplitude < 0) // Drop negative values
            amplitude = 0;
            int yAxis = (int)(leftTop + 
                ((leftBottom - leftTop) * amplitude) / 100);  
                        // Arbitrary factor
            pen.Color = Color.FromArgb(0, 0, (int)amplitude % 255);
            offScreenDC.DrawLine(pen, xAxis, leftTop, xAxis, yAxis);
        }
        // Draw right channel
        for (int xAxis = rightLeft; xAxis < rightRight; xAxis++)
        {
            double amplitude = (int)_fftRight[(int)(((double)
            (_fftRight.Length) / (double)(width)) * xAxis)];
            if (amplitude < 0)
            amplitude = 0;
            int yAxis = (int)(rightBottom - 
            ((rightBottom - rightTop) * amplitude) / 100);
            pen.Color = Color.FromArgb(0, 0, (int)amplitude % 255);
            offScreenDC.DrawLine(pen, xAxis, rightBottom, xAxis, yAxis);
        }
        // Clean up
        pictureBox.Image = _canvasFrequencyDomain;
        offScreenDC.Dispose();
    }
}

License

This article, along with any associated source code and files, is licensed under The GNU General Public License (GPLv3)


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Comments and Discussions

 
QuestionERROR Pin
TomasHornych4-May-23 0:07
TomasHornych4-May-23 0:07 
Question: Audio exception System.NullReferenceException: Object reference not set to an instance of an object. Pin
Member 1478349713-May-22 7:11
Member 1478349713-May-22 7:11 
Questionnamespace Pin
Member 118958305-Jul-20 5:18
Member 118958305-Jul-20 5:18 
GeneralMy vote of 1 Pin
Metafunken3-Mar-15 2:13
Metafunken3-Mar-15 2:13 
GeneralRe: My vote of 1 Pin
Member 1150355227-May-15 4:58
Member 1150355227-May-15 4:58 
GeneralRe: My vote of 1 Pin
Metafunken30-Jul-15 4:26
Metafunken30-Jul-15 4:26 
Questionis y axis desibel or amplitude ? Pin
Member 1041172813-Oct-14 1:37
Member 1041172813-Oct-14 1:37 
Questionhow to open an existing wav file Pin
Member 228177120-Nov-13 11:12
Member 228177120-Nov-13 11:12 
GeneralMy vote of 5 Pin
Gun Gun Febrianza28-Aug-13 12:35
Gun Gun Febrianza28-Aug-13 12:35 
QuestionNullReferenceException occured PinPopular
MA_hosseini28-Feb-13 0:53
MA_hosseini28-Feb-13 0:53 
AnswerRe: NullReferenceException occured Pin
k0ennn28-Feb-13 22:51
k0ennn28-Feb-13 22:51 
AnswerRe: NullReferenceException occured Pin
James M Smith2-Mar-13 7:34
James M Smith2-Mar-13 7:34 
GeneralRe: NullReferenceException occured Pin
Gettor900011-Apr-13 23:42
Gettor900011-Apr-13 23:42 
GeneralMy vote of 5 Pin
sanosay9-Aug-12 3:09
sanosay9-Aug-12 3:09 
QuestionProblems with Windows 7 Pin
valeriopini13-Mar-12 0:51
valeriopini13-Mar-12 0:51 
GeneralMy vote of 1 Pin
rrossenbg12-Jan-12 5:33
rrossenbg12-Jan-12 5:33 
GeneralRe: My vote of 1 Pin
sanosay9-Aug-12 3:08
sanosay9-Aug-12 3:08 
Questionwhat are the values representing in arrays? [modified] Pin
D__I___O31-Aug-11 0:11
D__I___O31-Aug-11 0:11 
Questionis this code possible to save as Wav or MP3 File after recording process Pin
myatthu198617-Aug-11 23:37
myatthu198617-Aug-11 23:37 
GeneralMy vote of 5 Pin
AlexB4715-Jun-11 23:02
AlexB4715-Jun-11 23:02 
Generali want to convert it into WPF Pin
vishal_h18-May-11 23:21
vishal_h18-May-11 23:21 
GeneralProb with the frequency domain Pin
joeblogg6-Jan-11 8:03
joeblogg6-Jan-11 8:03 
GeneralRe: Prob with the frequency domain Pin
Viktor Signaievskyi29-Jan-11 5:31
Viktor Signaievskyi29-Jan-11 5:31 
QuestionHow to get the frequency in real-time? Pin
gmajkun22-Dec-10 19:54
gmajkun22-Dec-10 19:54 
AnswerRe: How to get the frequency in real-time? Pin
Viktor Signaievskyi29-Jan-11 5:37
Viktor Signaievskyi29-Jan-11 5:37 

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