waveOutWrite - sound duration

Crazy Joe Devola

Hi, I found some code to play sounds. It works well but I can't figure out how to change the duration of the sound, e.g. to play for 100ms, 1000ms, 5000ms etc. Here is the code. I added the DurationMillisecs parameter but I don't know how to utilize it.

BOOL Test1(long FREQUENCY, long DurationMillisecs)
{
// taken from http://www.tmsoft.com/tutorial-sound.html

#define BUFFERSIZE 4860 // 4k sound buffer

#define PI 3.14159265358979

HWAVEOUT hWaveOut; // Handle to sound card output
WAVEFORMATEX WaveFormat; // The sound format
WAVEHDR WaveHeader; // WAVE header for our sound data

char         Data\[BUFFERSIZE\];  // Sound data buffer

HANDLE       Done;              // Event Handle that tells us the sound has finished being played.
                                // This is a real efficient way to put the program to sleep
                                // while the sound card is processing the sound buffer
double x;
int i;

// \*\* Initialize the sound format we will request from sound card \*\*    
WaveFormat.wFormatTag = WAVE\_FORMAT\_PCM;     // Uncompressed sound format
WaveFormat.nChannels = 2;                    // 1=Mono 2=Stereo
WaveFormat.wBitsPerSample = 8;               // Bits per sample per channel
WaveFormat.nSamplesPerSec = 11025; //1000\*(DurationMillisecs/1000);           // Sample Per Second
WaveFormat.nBlockAlign = WaveFormat.nChannels \* WaveFormat.wBitsPerSample / 8;
WaveFormat.nAvgBytesPerSec = (WaveFormat.nSamplesPerSec \* WaveFormat.nBlockAlign);    

WaveFormat.cbSize = 0;

// \*\* Create our "Sound is Done" event \*\*
Done = CreateEvent (0, FALSE, FALSE, 0);

// \*\* Open the audio device \*\*
if (waveOutOpen(&hWaveOut,0,&WaveFormat,(DWORD) Done,0,CALLBACK\_EVENT) != MMSYSERR\_NOERROR) 
{        
    MessageBox(0,"Sound card cannot be opened.", "error", 0);
    return TRUE;
}

// \*\* Make the sound buffer \*\*    
for (i=0; i < BUFFERSIZE; i++)
{        
    // \*\* Generate the sound wave based on FREQUENCY define
    // \*\* x will have a range of -1 to +1
    x = sin(i\*2.0\*PI\*(FREQUENCY)/(double)WaveFormat.nSamplesPerSec); 
    
    // \*\* scale x to a range of 0-255 (signed char) for 8 bit sound reproduction \*\*
    Data\[i\] = (char)(127\*x+128);
}


// \*\* Create the wave header for our sound buffer \*\*
WaveHeader.lpDa

enhzflep

Duration(msec) / 1000.0 = durationSec durationSec * samplesPerSecond = numOfSamplesRequired for (i=0; i<numOfSamplesRequired; i++) { // ** Generate the sound wave based on FREQUENCY define } WaveHeader.dwBufferLength = numOfSamplesRequired * bytesPerSample

Crazy Joe Devola

Thanks. I didn't quite understand what the code does. It seems to me you mean that I should loop for the number of seconds I want to sound to last. But that creates a non-smooth sounds, like noise. But I understood from your code that by playing with the size of BUFFERSIZE I can make the sound shorter or longer, and that seems to work well. Thank you.

enhzflep

That's okay. I hope you can forgive me for my poorly formatted (i.e - not at all) answer. I had hoped you would understand as much as I do from what I wrote, and it seems to have served its purpose. Have a nice weekend. :)

Crazy Joe Devola

It certainly did serve it's purpose. Thank you, it was helpful.