portaudio issue

gistfile1.cpp

#include <iostream>
#include <cmath>
#include <portaudio.h>


#define SAMPLE_RATE 22050

int input_channels = 2; /* <<< THIS VALUE TO ZERO WORKS!! */
int output_channels = 2;
int dds_pos = 0;

static int portaudio_callback(const void *input, void *output,
            unsigned long frameCount, const PaStreamCallbackTimeInfo* timeInfo,
            PaStreamCallbackFlags statusFlags, void *userData)
{
    int num_channels = 2;
    int buffer_size = frameCount * num_channels;
    int ch_idx;
    float* foutput = static_cast<float*>(output);

    for (int i=0; i<buffer_size; ) {
        for (ch_idx=0; ch_idx<num_channels; ++ch_idx) {
            foutput[i] = std::sin((2.0*M_PI*440.0*(dds_pos%SAMPLE_RATE))/SAMPLE_RATE);
            i++;
        }
        dds_pos++;
    }
    return paContinue;
}

int main(int argc, char** argv) {
    PaStream *stream;
    PaError err;

    err = Pa_Initialize();
    if( err != paNoError ) {
        std::cerr << "PortAudio error: " << Pa_GetErrorText( err ) << std::endl;
        return 0;
    }

    PaHostApiIndex api_idx;

    const PaHostApiInfo* info = Pa_GetHostApiInfo(Pa_GetDefaultHostApi());

    std::cerr << "Default device: " << info->name << std::endl;

    for (api_idx = 0; api_idx < Pa_GetHostApiCount(); ++api_idx) {
        info = Pa_GetHostApiInfo(api_idx);
        std::cerr << "device " << api_idx << ": " << info->name << std::endl;
    }

    //int frames_per_buffer = SAMPLE_RATE;
    int frames_per_buffer = paFramesPerBufferUnspecified;

    /* Open an audio I/O stream. */
    err = Pa_OpenDefaultStream( &stream,
                                input_channels,          /* input channels */
                                output_channels,          /* output */
                                paFloat32,  /* 32 bit floating point output */
                                SAMPLE_RATE,
                                frames_per_buffer, /* frames per buffer, i.e. the number
                                                   of sample frames that PortAudio will
                                                   request from the callback. Many apps
                                                   may want to use
                                                   paFramesPerBufferUnspecified, which
                                                   tells PortAudio to pick the best,
                                                   possibly changing, buffer size.*/
                                portaudio_callback, /* this is your callback function */
                                static_cast<void*>(0) ); /*This is a pointer that will be passed to
                                                   your callback*/
    if( err != paNoError ) {
        std::cerr << "PortAudio error: " << Pa_GetErrorText( err ) << std::endl;
        return 0;
    }

    err = Pa_StartStream( stream );
    if( err != paNoError ) {
        std::cerr << "PortAudio error: " << Pa_GetErrorText( err ) << std::endl;
        return 0;
    }


    for (int i=0;i<10;++i) {
        Pa_Sleep(1000);
    }


    err = Pa_StopStream(stream);
    if (err != paNoError) {
        std::cerr << "PortAudio error: " << Pa_GetErrorText(err) << std::endl;
        return 0;
    }

    err = Pa_CloseStream(stream);
    if (err != paNoError) {
        std::cerr << "PortAudio error: " << Pa_GetErrorText(err) << std::endl;
        return 0;
    }

    err = Pa_Terminate();
    if (err != paNoError) {
        std::cerr << "PortAudio error: " << Pa_GetErrorText(err) << std::endl;
        return 0;
    }

    return 0;
}