/* $Id: patest_ringmix.c,v 1.2 2003/03/02 08:01:42 dmazzoni Exp $ */#include "stdio.h"#include "portaudio.h"/* This will be called asynchronously by the PortAudio engine. */static int myCallback( void *inputBuffer, void *outputBuffer,                       unsigned long framesPerBuffer, PaTimestamp outTime, void *userData ){    float *out = (float *) outputBuffer;    float *in  = (float *) inputBuffer;    float leftInput, rightInput;    unsigned int i;    if( inputBuffer == NULL ) return 0;    /* Read input buffer, process data, and fill output buffer. */    for( i=0; i<framesPerBuffer; i++ )    {        leftInput = *in++;      /* Get interleaved samples from input buffer. */        rightInput = *in++;        *out++ = leftInput * rightInput;            /* ring modulation */        *out++ = 0.5f * (leftInput + rightInput);   /* mix */    }    return 0;}/* Open a PortAudioStream to input and output audio data. */int main(void){    PortAudioStream *stream;    Pa_Initialize();    Pa_OpenDefaultStream(        &stream,        2, 2,            /* stereo input and output */        paFloat32,  44100.0,        64,  0,          /* 64 frames per buffer, let PA determine numBuffers */        myCallback, NULL );    Pa_StartStream( stream );    Pa_Sleep( 10000 );    /* Sleep for 10 seconds while processing. */    Pa_StopStream( stream );    Pa_CloseStream( stream );    Pa_Terminate();    return 0;}