OpenAL for voicechat

Hi!

I'm using OpenAL for the output of a voicechat. It works great with 2 participants that talk to each other (=> only one stream is received per client). If a 3rd client connects and sends his stream (=> 2 streams are received per client) the final result is that both streams are played somehow cut (it's difficult to explain).

The technical stuff:
I'm using one source per received stream and each source uses a buffer queue with 4 buffers assigned. The stream is sent with udp over lan (100 Mbit => the problem is not caused by latency). I'm using OpenAL 1.1.

Ok, first of all I thought the packets aren't received correct anymore after the 3rd client connects. But then I wrote a [ms] timestamp into a logfile everytime I received a packat and they are still coming correctly.

=> The problem must be the output code somehow. Maybe I missed something so that the sources aren't correctly mixed together or something.

Here the important OpenAL code:
//------------------------------------------------------------
//Initializes OpenAL:
////////////////////////
pOutputDevice = alcOpenDevice(NULL); //Get handle to device
pOutputContext = alcCreateContext(pOutputDevice, NULL); //Create audio context
alcMakeContextCurrent(pOutputContext); //Set active context
if(alcGetError(pOutputDevice) != ALC_NO_ERROR) //Do an error check
{
	closesocket(voice_clientsock);
	voice_clientsock = 0;
	waveInClose(voice_recHandle);
	return _VAR(-1);
}
alGetError(); //Clear the bit

//Initializes the Listener:
ALfloat ListenerPos[] = {0.0, 0.0, 0.0};
ALfloat ListenerVel[] = {0.0, 0.0, 0.0};
ALfloat ListenerOri[] = {0.0, 0.0, -1.0, 0.0, 1.0, 0.0};
alListenerfv(AL_POSITION, ListenerPos);
alListenerfv(AL_VELOCITY, ListenerVel);
alListenerfv(AL_ORIENTATION, ListenerOri);

//Initializes a OpenAL Source:
soundsOut_current->next = 0;
soundsOut_current->radioid = radioid;
soundsOut_current->clientid = sender_clientid;
//Create the buffers for playing the sound
alGenBuffers(outputBuffer_nBufs, soundsOut_current->buffers);
if (alGetError() != AL_NO_ERROR) return 0;

//Initialize all Buffers
for(int i=0;i<outputBuffer_nBufs;i++) alBufferData(soundsOut_current->buffers[i], AL_FORMAT_MONO16, decoded_buffer, voice_Bufsize, voice_SamplesPerSecond);

//Generate the sound source
alGenSources(1, &soundsOut_current->source);
if(alGetError() != AL_NO_ERROR) return 0;

//Inizializes the Bufferqueue
alSourceQueueBuffers(soundsOut_current->source, outputBuffer_nBufs, soundsOut_current->buffers);
alSourcef(soundsOut_current->source, AL_PITCH, 1.0f);
alSourcef(soundsOut_current->source, AL_GAIN, 1.0f);
//Create a normal 2D Sound
alSource3f(soundsOut_current->source, AL_POSITION, 0.0, 0.0, 0.0);
alSource3f(soundsOut_current->source, AL_VELOCITY, 0.0, 0.0, 0.0);
alSourcei(soundsOut_current->source, AL_SOURCE_RELATIVE, AL_TRUE);
alSourcei(soundsOut_current->source, AL_LOOPING, AL_FALSE);


//Updates the buffers everytime a packet is received:
//////////////////////////////////////////////////////

ALint processed, state;
alGetSourcei(soundsOut_current->source, AL_SOURCE_STATE, &state);
alGetSourcei(soundsOut_current->source, AL_BUFFERS_PROCESSED, &processed);

if(processed > 0) //If there is a free buffer
{
	ALuint buffer;
	alSourceUnqueueBuffers(soundsOut_current->source, 1, &buffer);
	//Fill the buffer with the received data
	alBufferData(buffer, AL_FORMAT_MONO16, decoded_buffer, voice_Bufsize, voice_SamplesPerSecond);
        alSourceQueueBuffers(soundsOut_current->source, 1, &buffer);
}
// Restart in case we didn't get more data in time
if(state != AL_PLAYING) alSourcePlay(soundsOut_current->source);

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


Any ideas? I'm really getting stuck at this bug. I tested every possible reason of this problem with no success.

Thanks for your help!

Best regards,
Peter Soxberger

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