alsa-hello-sine.c

#include <stdio.h>
#include <math.h>
#include <alsa/asoundlib.h>

int main() {
    snd_pcm_t *pcm;
    snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0);

    snd_pcm_hw_params_t *hw_params;
    snd_pcm_hw_params_alloca(&hw_params);
    snd_pcm_hw_params_any(pcm, hw_params);
    snd_pcm_hw_params_set_access(pcm, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
    snd_pcm_hw_params_set_format(pcm, hw_params, SND_PCM_FORMAT_S16_LE);
    snd_pcm_hw_params_set_channels(pcm, hw_params, 1);
    snd_pcm_hw_params_set_rate(pcm, hw_params, 48000, 0);
    snd_pcm_hw_params_set_periods(pcm, hw_params, 10, 0);
    snd_pcm_hw_params_set_period_time(pcm, hw_params, 100000, 0); // 0.1 seconds
    snd_pcm_hw_params(pcm, hw_params);


    short samples[48000] = {0};

    for (int i=0; i < 48000; i++) {
        samples[i] = 10000 * sinf(2 * 3.14 * 200 * ((float)i / 48000));
    };

    snd_pcm_writei(pcm, samples, 48000);


    snd_pcm_drain(pcm);
    snd_pcm_close(pcm);

    return 0;
};