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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)


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Comments and Discussions

 
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 
We are using this code for a application that requires immediate response times, EMGSwitch.com. With some slower computers that get momentarily stress, delays of a second or longer can appear in the microphone input signal, regaurdless of the number of buffers used. Is there any way to avoid this or tell what the delay is?
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 
GeneralRe: Media File Pin
Eric Hdz25-Apr-15 14:43
Eric Hdz25-Apr-15 14:43 
GeneralShutdown addition Pin
firmwaredsp31-Oct-07 22:26
firmwaredsp31-Oct-07 22:26 
GeneralRe: Shutdown addition Pin
Ri Qen-Sin20-Nov-07 17:39
Ri Qen-Sin20-Nov-07 17:39 
GeneralRe: Shutdown addition Pin
Jeff Morton27-Nov-07 2:57
Jeff Morton27-Nov-07 2:57 
GeneralRe: Shutdown addition Pin
firmwaredsp27-Nov-07 23:21
firmwaredsp27-Nov-07 23:21 
QuestionHow it works?? Pin
Ibrahim Dwaikat28-Oct-07 9:22
Ibrahim Dwaikat28-Oct-07 9:22 
AnswerRe: How it works?? Pin
j_morton28-Oct-07 9:29
j_morton28-Oct-07 9:29 
GeneralRe: How it works?? Pin
Ibrahim Dwaikat28-Oct-07 9:34
Ibrahim Dwaikat28-Oct-07 9:34 
GeneralRe: How it works?? Pin
firmwaredsp31-Oct-07 22:47
firmwaredsp31-Oct-07 22:47 
GeneralRe: How it works?? Pin
Jeff Morton28-Nov-07 3:44
Jeff Morton28-Nov-07 3:44 
GeneralVery nice Pin
blackjack215023-Oct-07 1:01
blackjack215023-Oct-07 1:01 
QuestionHow To Get Frequency, or Period of the Wave? Pin
Paul Chin PC29-Sep-07 4:45
Paul Chin PC29-Sep-07 4:45 

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