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Uses a buffer for writing audio to an aiff file.
/* 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;
}
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