microphone signal level

iim

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Mar 24, 2004, 7:10:58 PM3/24/04

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I need a small program to measure the signal level from microphone via sound card. Anybody can help ?

KL Chin

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Mar 24, 2004, 9:03:19 PM3/24/04

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Hi,

Pls visit
http://bdn.borland.com/all/0,1435,s|50038|99,00.htm

look for 17610_real_time_audio_meter.zip

Regards
KL Chin

"iim" <imamsi...@yahoo.com.sg> wrote in message
news:40622392$1...@newsgroups.borland.com...

Mark Jacobs

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Apr 2, 2004, 3:30:27 PM4/2/04

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In the public section of your form, add the following :-

public: // User declarations
char erst[199];
unsigned char wvbfr[99];
HWAVEIN phwo;
WAVEFORMATEX pwfx;
MMRESULT wh;
WAVEHDR wvhd;
void __fastcall ProcessInput();

then on the form's paint event put this :-

//--------------------------------------------------------------------------
-
void __fastcall TForm1::FormPaint(TObject *Sender)
{
static bool clld=false;
if (clld) return;
clld=true;
pwfx.cbSize=0;
pwfx.wFormatTag=WAVE_FORMAT_PCM;
pwfx.nChannels=2;
pwfx.nSamplesPerSec=44100;
pwfx.wBitsPerSample=16;
pwfx.nAvgBytesPerSec=44100*2*16/8;
pwfx.nBlockAlign=2*16/8;
wh=waveInOpen(&phwo,WAVE_MAPPER,&pwfx,(DWORD)WaveInProc,
(DWORD)this,CALLBACK_FUNCTION);
if (wh!=MMSYSERR_NOERROR)
{
waveOutGetErrorText(wh,erst,190); Edit3->Text="Error="+AnsiString(erst);
zcMMTimer1->Enabled=false;
}
else zcMMTimer1->Enabled=true;
}
//--------------------------------------------------------------------------
-

Somewhere in the form module declare the following callback functions :-

void CALLBACK WaveInProc(HWAVEIN waveIn,UINT uMsg,
DWORD dwInstance,
DWORD dwParam1,DWORD
dwParam2)
{
if (uMsg==MM_WIM_DATA) Form1->ProcessInput();
}
//--------------------------------------------------------------------------
-
void __fastcall TForm1::ProcessInput()
{
short *mybf=(short *)wvbfr;
waveInStop(phwo);
wh=waveInUnprepareHeader(phwo,&wvhd,sizeof(WAVEHDR));
if (wh!=MMSYSERR_NOERROR) return;
zcDinMeter1->Value=(int)mybf[0]*100*zSlideBar1->Value/32768;
zcDinMeter2->Value=(int)mybf[1]*100*zSlideBar1->Value/32768;
zcMMTimer1->Enabled=true;
}
//--------------------------------------------------------------------------
-

Add a timer to the form. It should be set to an interval of 50ms or less to
be useful, but 100ms seems to be adequate. I use Ziegler's Multimedia Timer
so I can get good results from 20ms resolution. In the timer's OnTimer
event, put the following :-

//--------------------------------------------------------------------------
-
void __fastcall TForm1::zcMMTimer1Timer(TObject *Sender)
{
unsigned int vl; int mcierr,ii,jj;
zcMMTimer1->Enabled=false;
wvbfr[0]='\0'; wvbfr[1]='\0'; wvbfr[2]='\0'; wvbfr[3]='\0';
wvhd.lpData=wvbfr; wvhd.dwBufferLength=4;
wvhd.dwLoops=0; wvhd.dwFlags=0; waveInStop(phwo);
if (waveInPrepareHeader(phwo,&wvhd,sizeof(WAVEHDR))==MMSYSERR_NOERROR)
{
waveInAddBuffer(phwo,&wvhd,sizeof(WAVEHDR));
waveInStart(phwo);
}
}
//--------------------------------------------------------------------------
-

Hey presto, the values in ProcessInput()'s mybf buffer are :-
Left Channel = mybf[0]
Right Channel=mybf[1]
with a range of -32767 to 32767 in each case.

I verified my results on a Soundblaster Live card. I have noticed that the
Realtek AC97 Soundcard on another PC did not work properly. It could be
indicative of faulty sound drivers. I'll try other PCs and report back.
However, the code above has been arrived at painstakingly. Thankyou
Microsoft!
--
Mark Jacobs

"iim" <imamsi...@yahoo.com.sg> wrote in message
news:40622392$1...@newsgroups.borland.com...
>

Mark Jacobs

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Apr 2, 2004, 3:50:21 PM4/2/04

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I forgot to add, in the form closequery event, put this :-

if (zcMMTimer1->Enabled)
{
zcMMTimer1->Enabled=false; waveInClose(phwo);
}
--
Mark Jacobs

"Mark Jacobs" <ma...@losethisbitjacobsm.com> wrote in message
news:406d...@newsgroups.borland.com...

> In the public section of your form, add the following :-

> ...// Lots snipped ...

Mark Jacobs

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Apr 2, 2004, 4:05:08 PM4/2/04

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Correction. It should be :-
//--------------------------------------------------------------------------
-

void __fastcall TForm1::FormCloseQuery(TObject *Sender, bool &CanClose)

{

zcMMTimer1->Enabled=false; waveInStop(phwo);

waveInUnprepareHeader(phwo,&wvhd,sizeof(WAVEHDR));

waveInClose(phwo); CanClose=true;

}

//--------------------------------------------------------------------------
-

--
Mark Jacobs

"Mark Jacobs" <ma...@losethisbitjacobsm.com> wrote in message

news:406dd216$1...@newsgroups.borland.com...

Mark Jacobs

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Apr 3, 2004, 4:06:04 PM4/3/04

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I have had problems with Ziegler's Multimedia Timer, so use a standard system
timer. I can get as low as 20ms interval.
--
Mark Jacobs