Click here to Skip to main content
11,629,614 members (63,425 online)
Click here to Skip to main content

Sound Activated Recorder with Spectrogram in C#

, 27 Jan 2008 GPL3 206.2K 22.8K 197
Rate this:
Please Sign up or sign in to vote.
Audio event processing with visual display
SoundCatcher

Introduction

This project demonstrates an implementation of the waterfall spectrogram and use of statistical data to trigger events in near real-time. This code is an elaboration of my previous submission (SoundViewer). This demonstration utilizes the Wave classes developed by Ianier Munoz.

Using the Code

Audio is supplied by the default input device which is typically the microphone. Events are triggered when audio amplitude exceeds the desired threshold value, which can be set under Options on the menu bar. To make this more useful, I've added functionality to save the stream to disk which results in a nice sound activated recorder.

Points of Interest

In order to draw the spectrogram fast enough to allow for near real-time operation, I needed to write directly to memory using unsafe code.

// lock image
PixelFormat format = canvas.PixelFormat;
BitmapData data = 
    canvas.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadOnly, format);
int stride = data.Stride;
int offset = stride - width * 4;

// draw image
try
{
  unsafe
  {
    byte* pixel = (byte*)data.Scan0.ToPointer();
    // for each column
    for (int y = 0; y <= height; y++)
    {
      if (y < _fftLeftSpect.Count)
      {
        // for each row
        for (int x = 0; x < width; x++, pixel += 4)
        {
          double amplitude = ((double[])_fftLeftSpect[_fftLeftSpect.Count - y - 1])
                [(int)(((double)(_fftLeft.Length) / (double)(width)) * x)];
          double color = GetColor(min, max, range, amplitude);
          pixel[0] = (byte)0;
          pixel[1] = (byte)color;
          pixel[2] = (byte)0;
          pixel[3] = (byte)255;
        }
        pixel += offset;
      }
    }
  }
}
catch (Exception ex)
{
  Console.WriteLine(ex.ToString());
}

// unlock image
canvas.UnlockBits(data);

I noticed that the results vary wildly depending on the hardware and associated drivers being used.

Some things I'd like to experiment with further when I get the time:

  1. Use of frequency domain to produce "motion" detector equivalent
  2. Use of spectrogram in sound identification
  3. Improving performance/robustness

History

  • 01/16/2008: Created

License

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

Share

About the Author

Jeff Morton
Systems / Hardware Administrator
United States United States
No Biography provided

You may also be interested in...

Comments and Discussions

 
QuestionDelay/Latency Pin
hieronymusde13-Aug-13 11:21
memberhieronymusde13-Aug-13 11:21 
GeneralMy vote of 5 Pin
hieronymusde13-Aug-13 10:04
memberhieronymusde13-Aug-13 10:04 
QuestionHelp for operation on a modulated signal Pin
galbandrea14-Apr-13 22:13
membergalbandrea14-Apr-13 22:13 
Bug"В экземпляре объекта не задана ссылка на объект." Pin
Member 99607234-Apr-13 1:54
memberMember 99607234-Apr-13 1:54 
Questionis there a way to select the iinput device (directx name ?) Pin
patrick zuili17-Mar-13 18:34
memberpatrick zuili17-Mar-13 18:34 
Generalamazing one Pin
Member 810718412-Jan-13 5:07
memberMember 810718412-Jan-13 5:07 
GeneralMy vote of 5 Pin
javcastaalm23-Nov-12 9:08
memberjavcastaalm23-Nov-12 9:08 
GeneralThanks Pin
LeviButler3-Nov-12 13:27
memberLeviButler3-Nov-12 13:27 
GeneralMy vote of 5 Pin
Member 806726522-May-12 0:47
memberMember 806726522-May-12 0:47 
Questiondraw spectrogram with a wav file. Pin
jacky_zz4-Feb-12 18:27
memberjacky_zz4-Feb-12 18:27 
QuestionLocking up when closing if there is activity Pin
programmerdon17-Jan-12 5:46
memberprogrammerdon17-Jan-12 5:46 
QuestionObject reference not set to an instance of an object Pin
deepak thomas5-Dec-11 4:01
memberdeepak thomas5-Dec-11 4:01 
AnswerRe: Object reference not set to an instance of an object Pin
deepak thomas5-Dec-11 6:57
memberdeepak thomas5-Dec-11 6:57 
For Windows 7

Visual Studio 2008

Click the "Build" -> "Configuration Manager..." menu option. Click the "Active solution platform" drop-down menu and select "New...". A dialog will open, change the type to "x86", click "OK", and rebuild
GeneralRe: Object reference not set to an instance of an object Pin
Member 1029319526-Sep-13 18:08
memberMember 1029319526-Sep-13 18:08 
QuestionSound Catcher freezes on Exit in Win 7 32-bit Pin
Member 836994911-Nov-11 11:13
memberMember 836994911-Nov-11 11:13 
AnswerRe: Sound Catcher freezes on Exit in Win 7 32-bit Pin
Timothy Ayodele14-Jan-12 1:54
memberTimothy Ayodele14-Jan-12 1:54 
QuestionPlease how can i make the recording every 1 hour Pin
Timothy Ayodele2-Nov-11 7:26
memberTimothy Ayodele2-Nov-11 7:26 
QuestionVote 5 Pin
serega4675-Aug-11 0:41
memberserega4675-Aug-11 0:41 
GeneralIn VB.NET Pin
emicroxxx23-May-11 2:55
memberemicroxxx23-May-11 2:55 
GeneralMy vote of 5 Pin
abdillahi26-Apr-11 22:23
groupabdillahi26-Apr-11 22:23 
QuestionHow can i save output to .txt ? Pin
stefan_brato27-Nov-10 16:48
memberstefan_brato27-Nov-10 16:48 
QuestionSpectrogram Disappears Pin
GeoNav12-Jul-10 18:26
memberGeoNav12-Jul-10 18:26 
QuestionGPLv2 Pin
Member 42771197-Jul-10 10:00
memberMember 42771197-Jul-10 10:00 
QuestionHow to generate wave-form if we have the byte-array with us. Pin
Mark0211-Mar-10 23:06
memberMark0211-Mar-10 23:06 
GeneralIntegration Time Pin
GeoNav17-Feb-10 4:17
memberGeoNav17-Feb-10 4:17 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Terms of Use | Mobile
Web04 | 2.8.150723.1 | Last Updated 28 Jan 2008
Article Copyright 2008 by Jeff Morton
Everything else Copyright © CodeProject, 1999-2015
Layout: fixed | fluid