Click here to Skip to main content
11,412,833 members (73,503 online)
Click here to Skip to main content

Sound Activated Recorder with Spectrogram in C#

, 27 Jan 2008 GPL3
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

Comments and Discussions

 
QuestionCan't run the program in Vista 64bit Pin
Yasir Salih Osman at 7-Aug-09 23:36
memberYasir Salih Osman7-Aug-09 23:36 
AnswerRe: Can't run the program in Vista 64bit Pin
Fullmetal99012 at 11-Sep-09 8:20
memberFullmetal9901211-Sep-09 8:20 
AnswerRe: Can't run the program in Vista 64bit Pin
Rahdu at 18-Oct-10 23:09
memberRahdu18-Oct-10 23:09 
AnswerRe: Can't run the program in Vista 64bit Pin
Member 3209383 at 12-Apr-11 13:10
memberMember 320938312-Apr-11 13:10 
AnswerRe: Can't run the program in Vista 64bit Pin
Rebmem15 at 29-Sep-11 19:33
memberRebmem1529-Sep-11 19:33 
Questionhow can i do it reverse? [modified] Pin
mojimoj at 2-Aug-09 22:05
membermojimoj2-Aug-09 22:05 
GeneralExcellent piece of work Jeff Pin
maxima120 at 4-Jul-09 13:17
membermaxima1204-Jul-09 13:17 
GeneralRe: Excellent piece of work Jeff Pin
Jeff Morton at 5-Jul-09 6:46
memberJeff Morton5-Jul-09 6:46 
GeneralThrows exception when using Freq &lt; 11025 Hz Pin
k^s at 10-Jun-09 8:07
memberk^s10-Jun-09 8:07 
QuestionHow do I get it to work? Pin
Maiden Computer Company at 22-Apr-09 11:48
memberMaiden Computer Company22-Apr-09 11:48 
AnswerRe: How do I get it to work? Pin
Jeff Morton at 22-Apr-09 11:51
memberJeff Morton22-Apr-09 11:51 
QuestionError in Frequency domain? Pin
Elysium at 8-Mar-09 12:17
memberElysium8-Mar-09 12:17 
AnswerRe: Error in Frequency domain? Pin
Jeff Morton at 8-Mar-09 12:41
memberJeff Morton8-Mar-09 12:41 
GeneralRe: Error in Frequency domain? Pin
Elysium at 8-Mar-09 23:02
memberElysium8-Mar-09 23:02 
I did have another thought I'll need to check...to get the single spike in the freq domain you'll need an integral number of sine wave cycles in your sample window otherwise you will see some other spurious frequency content (not sure if that is what we are seeing).
QuestionQuestion on how to get the frequencies Pin
kyanmark_johnwill at 2-Mar-09 14:52
memberkyanmark_johnwill2-Mar-09 14:52 
AnswerRe: Question on how to get the frequencies Pin
hazeljane at 13-Mar-09 4:49
memberhazeljane13-Mar-09 4:49 
GeneralRe: Question on how to get the frequencies Pin
Jeff Morton at 13-Mar-09 11:34
memberJeff Morton13-Mar-09 11:34 
GeneralRe: Question on how to get the frequencies Pin
afmf at 23-Oct-09 2:54
memberafmf23-Oct-09 2:54 
GeneralRe: Question on how to get the frequencies Pin
afmf at 3-Nov-09 0:38
memberafmf3-Nov-09 0:38 
GeneralRe: Question on how to get the frequencies Pin
Muammar© at 1-Jan-10 1:56
member Muammar©1-Jan-10 1:56 
Questionspectrogram of a wav file Pin
plouvou at 12-Jan-09 10:59
memberplouvou12-Jan-09 10:59 
AnswerRe: spectrogram of a wav file Pin
Tae-Sung at 18-Jan-09 10:07
memberTae-Sung18-Jan-09 10:07 
GeneralRe: spectrogram of a wav file Pin
tortexy at 2-Feb-09 13:50
membertortexy2-Feb-09 13:50 
GeneralRe: spectrogram of a wav file Pin
GeoNav at 31-Oct-09 2:52
memberGeoNav31-Oct-09 2:52 
GeneralDraw waveform for already existing wave file Pin
jugal_piet@indiatimes.com at 5-Jan-09 21:26
memberjugal_piet@indiatimes.com5-Jan-09 21:26 
GeneralVery great app Pin
Mr. Yi at 26-Nov-08 5:31
memberMr. Yi26-Nov-08 5:31 
GeneralBug in event detection - left channel only is used Pin
Atis Straujums at 9-Oct-08 11:43
memberAtis Straujums9-Oct-08 11:43 
GeneralRe: Bug in event detection - left channel only is used Pin
Jeff Morton at 9-Oct-08 13:16
memberJeff Morton9-Oct-08 13:16 
GeneralAnother hi! Pin
stano at 24-Sep-08 19:16
memberstano24-Sep-08 19:16 
GeneralAnger detection software Pin
100,000 Cold Calls at 12-Aug-08 12:44
member100,000 Cold Calls12-Aug-08 12:44 
GeneralRe: Anger detection software Pin
flowerchild12 at 8-Feb-09 13:48
memberflowerchild128-Feb-09 13:48 
Generalthe file is not saving ...!! Pin
Ashok Nalam at 9-Jul-08 2:05
memberAshok Nalam9-Jul-08 2:05 
QuestionDisplay Of Frequencies Pin
RonD at 25-May-08 5:17
memberRonD25-May-08 5:17 
AnswerRe: Display Of Frequencies Pin
Member 4708801 at 1-Aug-08 16:24
memberMember 47088011-Aug-08 16:24 
GeneralRe: Display Of Frequencies Pin
Member 4708801 at 1-Aug-08 16:25
memberMember 47088011-Aug-08 16:25 
QuestionHow can i make it faster? Pin
pauloricca at 16-May-08 7:20
memberpauloricca16-May-08 7:20 
AnswerRe: How can i make it faster? Pin
Jeff Morton at 16-May-08 8:05
memberJeff Morton16-May-08 8:05 
GeneralRe: How can i make it faster? Pin
pauloricca at 19-May-08 0:42
memberpauloricca19-May-08 0:42 
GeneralTwo Questions Pin
rodriguesd at 23-Mar-08 1:45
memberrodriguesd23-Mar-08 1:45 
GeneralThis is great stuff Pin
peter.roca at 6-Mar-08 10:34
memberpeter.roca6-Mar-08 10:34 
GeneralHi Pin
circass at 4-Mar-08 7:32
membercircass4-Mar-08 7:32 
GeneralJust a thought... Pin
Ed.Poore at 29-Jan-08 14:53
memberEd.Poore29-Jan-08 14:53 
QuestionProblem with Solution file? Pin
EitsopGmail at 29-Jan-08 0:41
memberEitsopGmail29-Jan-08 0:41 
AnswerRe: Problem with Solution file? Pin
Jeff Morton at 29-Jan-08 1:16
memberJeff Morton29-Jan-08 1:16 
GeneralRe: Problem with Solution file? Pin
circass at 4-Mar-08 7:34
membercircass4-Mar-08 7:34 

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
Web03 | 2.8.150427.1 | Last Updated 28 Jan 2008
Article Copyright 2008 by Jeff Morton
Everything else Copyright © CodeProject, 1999-2015
Layout: fixed | fluid