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Sound visualizer in C#

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15 Aug 2007GPL3 434K   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)


Written By
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Comments and Discussions

 
GeneralMy vote of 5 Pin
Dennis Betten3-Nov-10 1:41
Dennis Betten3-Nov-10 1:41 
GeneralError Pin
dreje20105-Oct-10 23:53
dreje20105-Oct-10 23:53 
QuestionDoes this analyse the code with in milisecond accurancy? Pin
Rahdu15-Sep-10 9:50
Rahdu15-Sep-10 9:50 
GeneralDetect Peak on single channel Pin
survcopt5-Mar-10 3:47
survcopt5-Mar-10 3:47 
Questionhow can I determine the sound level without waveFormat ? Pin
fasialkk24-Feb-10 13:44
fasialkk24-Feb-10 13:44 
QuestionHow To Open Recorded Wav File Pin
Bill SerGio, The Infomercial King14-Jan-10 2:38
Bill SerGio, The Infomercial King14-Jan-10 2:38 
Generalimportant reguest Pin
seka2087-Dec-09 22:04
seka2087-Dec-09 22:04 
QuestionDoes not work in Windows 7 (64bit) Why? Pin
a.mueller2-Dec-09 5:31
a.mueller2-Dec-09 5:31 
AnswerRe: Does not work in Windows 7 (64bit) Why? PinPopular
eweewf15-Feb-10 8:42
eweewf15-Feb-10 8:42 
QuestionIs this available in VB.NET? Pin
Simon Williamson2-Apr-09 1:21
Simon Williamson2-Apr-09 1:21 
GeneralMedia file Pin
Babgi26-Mar-09 9:19
Babgi26-Mar-09 9:19 
GeneralRe: Media file Pin
gamosemalaka30-May-09 22:00
gamosemalaka30-May-09 22:00 
GeneralRe: Media file Pin
diogopms27-Jun-09 15:37
diogopms27-Jun-09 15:37 
GeneralRe: Media file Pin
Anky201111-Mar-10 22:34
Anky201111-Mar-10 22:34 
GeneralRe: Media file Pin
gerardo_00115-Mar-10 8:15
gerardo_00115-Mar-10 8:15 
QuestionWhere is the Documentation? Pin
Jasmine Pomelo19-Mar-09 7:37
Jasmine Pomelo19-Mar-09 7:37 
QuestionaudioFrameSize in waveformat correct ? Pin
radio_gaga8-Mar-09 8:16
radio_gaga8-Mar-09 8:16 
AnswerRe: audioFrameSize in waveformat correct ? Pin
Jeff Morton8-Mar-09 9:59
Jeff Morton8-Mar-09 9:59 
GeneralIt won't work on desktop PC Pin
max_99014-Feb-09 0:15
max_99014-Feb-09 0:15 
QuestionInput delays Pin
Joe Wright1-Sep-08 7:12
Joe Wright1-Sep-08 7:12 
AnswerRe: Input delays Pin
Jeff Morton1-Sep-08 12:45
Jeff Morton1-Sep-08 12:45 
GeneralIt works! Pin
Member 470880128-Aug-08 21:08
Member 470880128-Aug-08 21:08 
GeneralMedia File Pin
jonhbt13-Aug-08 22:36
jonhbt13-Aug-08 22:36 
GeneralRe: Media File Pin
Babgi26-Mar-09 9:12
Babgi26-Mar-09 9:12 
GeneralRe: Media File Pin
Anky201111-Mar-10 22:35
Anky201111-Mar-10 22:35 

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