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NF Spectrum analyzer software  (FreqAnalysis.exe)

The audio Frequency Analyzer and Fast Fourier Transform in .NET (C#).

 11.3.2007  start of date 

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(c) 2006 Pavel Pindora 

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.NET and Audio hardware handling

.NET and Audio hardware handling

I had implemented a audio functions,FFT  in .NET dll library SamplingSound.dll

 

This software using the sound card of your PC ( Pocket PC ) . The nf signal, connected to microphone inputs of  sound card ,  is converted into digital stream and this is stored to buffer for FFT  . 

 

 

 

 

For retrieves the number of input devices in the system we can used function NumDevices  

 

//[DllImport ("coredll.dll")] for Pocket PC

[DllImport("Winmm.dll")]

protected static extern int waveInGetNumDevs();

 

public static uint NumDevices()

{

return (uint)waveInGetNumDevs();

}

 

SetWAVEINCAPS( WAVE_MAPPER ) Get the capabilities of a specified audio input device.

 

 

[DllImport("Winmm.dll")]

protected static extern Wave.MMSYSERR waveInGetDevCaps(uint uDeviceID, byte[] pwic, uint cbwic);

 

 

 

public static object SetWAVEINCAPS(uint deviceId)

{

WAVEINCAPS capswavein = new WAVEINCAPS();

MMSYSERR result = waveInGetDevCaps(deviceId, capswavein, capswavein.Size);

if (MMSYSERR.NOERROR == result)

return capswavein;

else

return null;

}

 

Set sound card format

 

format = new WaveFormat(44100, 16, 1);

 

 

ffttransform = new FFT((int)FftPoints * ((format.wBitsPerSample * format.nChannels) / 8), SamplesPerSecond);

 

uint wTemp = WAVE_MAPPER;

wFr = (Int16)wTemp;

uint dwI = 0;

callback = new WaveCallback(WaveCallback);

hwnd = System.Diagnostics.Process.GetCurrentProcess().Handle;

 

and define callback

public delegate void WaveCallback(IntPtr DeviceAddress, int Msg, IntPtr InstanceDat, int wParam, int lParam);

 

 

#region WaveCallback

public void WaveCallback(IntPtr DeviceAddress, int Msg, IntPtr InstanceDat, int wParam, int lParam)

{

const int MM_WIM_OPEN = 0x3BE;

const int MM_WIM_CLOSE = 0x3BF;

const int MM_WIM_DATA = 0x3C0;

 

countBf++;

if (Msg == MM_WIM_DATA)

{

try

{

SamplingSound.WaveIn.WaveFile.BlockDone();

}

catch

{

}

}

if (Msg == MM_WIM_OPEN)

{

SetLabel4Text();

listBox1.Items.Add("WaveCallback: open WIM_OPEN");

}

}

#endregion WaveCallback
 

open Wave

#region waveInOpen

errMy = SamplingSound.WaveIn.waveInOpen(out sIn, wFr, format, callback, (IntPtr)0, Wave.CALLBACK_FUNCTION);

if (errMy == Wave.MMSYSERR.NOERROR)

listBox1.Items.Add("ok waveInOpen");

else

{

listBox1.Items.Add("error waveInOpen = " + errMy);

errMy = Wave.MMSYSERR.INVALHANDLE;

return;

}

#endregion waveInOpe

 

and start working thread. 

 

 

 

#region ThreadProc

private void ThreadProc()

{

MethodInvoker mi = new MethodInvoker(this.SetLabel2Text);

while (!Finished)

{

if (SamplingSound.WaveIn.WaveFile.m_recording == true)

{

countTh++;

Thread.Sleep(10);

}

else

{

if (Paused == true)

{

GetDataFromBuffer();

if (ffttransform.EndFFT == false && OutBuf.Count>0)

{// EndFFT nastavuje button Start a fn GetDataFromBuffer OutBuf

ffttransform.Transform(OutBuf);

OutBuf.Clear();

}

}

Thread.Sleep(10);

}

this.BeginInvoke(mi);

//if (countTh > 0) Finished = true;

}

}

#endregion ThreadProc

 

Start recording audio stream to buffer ( set size buffer to bytesPerBuf )

 

 

long bytesPerBuf = FftPoints * ((format.wBitsPerSample * format.nChannels) / 8);

 

//prepare buffer  for recording

errMy = SamplingSound.WaveIn.WaveFile.Preload((uint)wFr, hwnd, 1000, (int)bytesPerBuf, format);

 

errMy = SamplingSound.WaveIn.WaveFile.Start();

 

{// Calling

 

[DllImport("Winmm.dll")]

public static extern Wave.MMSYSERR waveInStart(IntPtr hwi);

 

 

 

 

 

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