[Openal-devel] Waveform and queued buffers

[-Tobias-]

Hi,

I have to implement a waveform synthesizer. Finally, it should mix sine
waves with different frequencies, and during runtime, these frequencies
change. So I have to use queing, I think. The code below produces a nice,
clear sound (sine wave) using a single buffer (see commented part). Using
multiple buffers and the Queue/Unqueue mechanism as shown, the same simple
sine wave sounds rippled/scratchy.

What is the reason for that?

Thanks a lot for your appreciated help,

Tobias

ALuint      uiBuffer;
ALuint      uiBuffers[2];
ALuint      uiSource;  
ALint       iState;
char data[BUFFERSIZE];
char data2[BUFFERSIZE];

// Initialize Framework
	ALFWInit();

	mexPrintf("PlayStatic Test Application\n");

	if (!ALFWInitOpenAL())
	{
		mexPrintf("Failed to initialize OpenAL\n");
		ALFWShutdown();
		return;
	}

	// Generate an AL Buffer
	//alGenBuffers( 1, &uiBuffer );
    alGenBuffers( 2, uiBuffers );


	alSourcei(uiSource, AL_LOOPING, AL_TRUE);	
	double pi=3.141592654;
	//for (int z = 0; z< BUFFERSIZE; z++) data[z] =
100*sin((double)z*(2*pi)/1000.0);//+128;//+100*sin(z*(2*pi)/400.0);
   
    double freq = 80;    
    for (int z = 0; z< BUFFERSIZE; z++) data[z] =
100*sin(z*2*pi*freq/SAMPLEFREQ)+128;
    for (int z = 0; z< BUFFERSIZE; z++) data2[z] =
100*sin((BUFFERSIZE+z)*2*pi*freq/SAMPLEFREQ)+128;
	
		
	int i=1;

	//alBufferData(uiBuffer, AL_FORMAT_MONO8, data, sizeof(data), SAMPLEFREQ);    
    alBufferData(uiBuffers[0], AL_FORMAT_MONO8, data, sizeof(data), 11024);
    alBufferData(uiBuffers[1], AL_FORMAT_MONO8, data2, sizeof(data2),
11024);
	

	// Generate a Source to playback the Buffer
    alGenSources( 1, &uiSource );

	// Attach Source to Buffer
	//alSourcei( uiSource, AL_BUFFER, uiBuffer );    
    alSourceQueueBuffers(uiSource,2,uiBuffers);

	// Play Source
	//playIt(uiSource);

	mexPrintf("Playing Source ");		
	alSourcePlay( uiSource );

	alGetSourcei( uiSource, AL_SOURCE_STATE, &iState);
	if (iState == AL_PLAYING)
		mexPrintf("confirmed!");

	if ((alGetError()) == AL_NO_ERROR)
		mexPrintf("No Errors!");

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