Uses a buffer for writing audio to an aiff file.

simple_buffer.c

/* simple_buffer.c
 * Jacob Joaquin <jacobjoaquin@gmail.com>
 * csoundblog.com
 *
 * Uses a buffer for writing audio to an aiff file.
 * (error handling not included)
 *
 * License:
 * GNU Lesser General Public License
 * http:/*www.gnu.org/copyleft/lesser.html
 *
 * libsndfile by Erik de Castro Lopo
 * http:/*www.mega-nerd.com/libsndfile/
 */

#include <math.h> 
#include <sndfile.h>
#include <stdlib.h>

const float two_pi = 6.2831853071795862;

int main()
{
    SNDFILE* sndfile;                                /* sound file */
    SF_INFO* sf_info;                                /* file properties */
    int sample_rate = 44100;                         /* Sample rate */
    int block_size = 100;                            /* Block size */
    int channels = 1;                                /* Mono */
    int nblocks = (sample_rate / block_size) * 4.0;  /* 4 seconds */
    float* frames_buffer;                            /* Audio output buffer */
    int frames_buffer_size;                          /* Length of buffer */
    float sine_out = 0.0;                            /* Oscillator value */
    float sine_phase = 0.0;                          /* Oscillator phase */
    float sine_inc = (1.0 / sample_rate) * 440.0;    /* Oscillator A 440 */
    
    /* Set sound file properties  */
    sf_info = (SF_INFO *) malloc(sizeof(SF_INFO));
    sf_info->samplerate = sample_rate;
    sf_info->channels = channels;
    sf_info->format = SF_FORMAT_AIFF | SF_FORMAT_PCM_16;
    
    /* Open sound file for writing */
    sndfile = sf_open("./simple_buffer.aif", SFM_WRITE, sf_info);

    /* Intialize frames_buffer */
    frames_buffer = (float*) malloc(channels * sizeof(float) * nblocks);
    frames_buffer_size = block_size * channels;
    
    /* Main audio loop */
    do
    {
        float* frame_ptr = frames_buffer;  /* Current frame */
        int frames = block_size;           /* Frames per block */
        
        /* Process audio block */
        do
        {
            /* Sine A 440 -3dB */
            sine_out = sin(sine_phase * two_pi) * 0.707; 
            sine_phase += sine_inc;
            
            if (sine_phase >= 1.0)
            {
                sine_phase -= 1.0;
            }

            /* Write sample to audio buffer */
            *frame_ptr++ = sine_out;
        } while (--frames);        

        /* Write audio buffer to sound file */
        sf_writef_float(sndfile, frames_buffer, frames_buffer_size);
    } while (--nblocks);
    
    /* Clean up and return */
    free(frames_buffer);
    sf_close(sndfile);
    return 0;
}