DemoPublic/Linux/Application/ALSA/SndPam/SndPam.c

/**
 * @file SndPam.c
 * @author  Rick Chan (cy187lion@sina.com)
 * @brief
 * @version 0.1
 * @date 2020-04-08
 * 
 * @copyright Copyright (c) 2020
 * 
 */
#include <stdio.h>
#include <stdlib.h>
#include <alsa/asoundlib.h>
#include <pthread.h>

#define PERIOD_CNT      16
#define PERIOD_FRAMES   512
#define PERIOD_BYTES    2048
#define BUF_SZ          (PERIOD_CNT * PERIOD_FRAMES)
#define TOTAL_BUF       (PERIOD_CNT * PERIOD_BYTES)


void init_pcm(snd_pcm_t *handle, unsigned int rate, unsigned int ch, unsigned int frames, unsigned int periods)
{
    int err;
    snd_pcm_hw_params_t *hw_params;
    // snd_pcm_sw_params_t *sw_params;
    snd_pcm_uframes_t period_size = frames;
    snd_pcm_uframes_t buffer_size = periods*frames;

    if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
        printf ("cannot allocate hardware parameter structure (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_any (handle, hw_params)) < 0) {
        printf ("cannot initialize hardware parameter structure (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_set_access (handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
        printf ("cannot set access type (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_set_format (handle, hw_params, SND_PCM_FORMAT_S16_LE)) < 0) {
        printf ("cannot set sample format (%s)\n",
                 snd_strerror (err));
        // exit (1);
    }
    if ((err = snd_pcm_hw_params_set_rate_near (handle, hw_params, &rate, 0)) < 0) {
        printf ("cannot set sample rate (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_set_periods_near(handle, hw_params, &periods, NULL)) < 0) {
        printf ("cannot set periods (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_set_period_size_near(handle, hw_params, &period_size, NULL)) < 0) {
        printf ("cannot set period size (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_set_buffer_size_near(handle, hw_params, &buffer_size)) < 0) {
        printf ("cannot set buffer size (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_set_channels (handle, hw_params, 2)) < 0) {
        printf ("cannot set channel count (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params (handle, hw_params)) < 0) {
        printf ("cannot set hardware parameters (%s)\n",
                 snd_strerror (err));
        exit (1);
    }

    /*snd_pcm_sw_params_alloca (&sw_params);

    if ((err = snd_pcm_sw_params_current(handle, sw_params)) < 0) {
        printf ("cannot get current software parameters (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_sw_params_set_start_threshold (handle, sw_params, 0)) < 0) {
        printf ("cannot set threshold (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
    if ((err = snd_pcm_sw_params (handle, sw_params)) < 0) {
        printf ("cannot set software parameters (%s)\n",
                 snd_strerror (err));
        exit (1);
    }*/
    if ((err = snd_pcm_prepare (handle)) < 0) {
        printf ("cannot prepare audio interface for use (%s)\n",
                 snd_strerror (err));
        exit (1);
    }
}

snd_pcm_t* init_playback(char output[], unsigned int rate, unsigned int ch, unsigned int frames, unsigned int periods)
{
    int err;
    snd_pcm_t *playback_handle;

    if ((err = snd_pcm_open (&playback_handle, output, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
        printf ("cannot open audio device %s (%s)\n",
                 output,
                 snd_strerror (err));
        exit (1);
    }
    init_pcm(playback_handle, rate, ch, frames, periods);
    return playback_handle;
}

#if 0
snd_pcm_t* init_capture(char input[])
{
    int err;
    snd_pcm_t *capture_handle;

    if ((err = snd_pcm_open (&capture_handle, input, SND_PCM_STREAM_CAPTURE, 0)) < 0) {
        printf ("cannot open audio device %s (%s)\n",
                 input,
                 snd_strerror (err));
        exit (1);
    }
    init_pcm(capture_handle);
    return capture_handle;
}
#endif

int main (int argc, char *argv[])
{
    snd_pcm_t* playback_handle;
    unsigned int rate;
    unsigned int ch;
    unsigned int frames;
    unsigned int periods;

    if (2==argc) {
        if (0==strcmp("-v", argv[1]))
            printf ("SndPam Version 1.0\r\n");

        if (0==strcmp("-h", argv[1]))
            printf ("SndPam <device>\r\nExp: SndPam plughw:0,0 <rate> <ch> <frames> <periods>\r\n");

        exit (0);
    }

    if (6!=argc) {
        printf ("SndPam <device>\r\nExp: SndPam plughw:0,0 <rate> <ch> <frames> <periods>\r\n");
        exit (0);
    }

    sscanf(argv[2], "%u", &rate);
    sscanf(argv[3], "%u", &ch);
    sscanf(argv[4], "%u", &frames);
    sscanf(argv[5], "%u", &periods);
    printf("Open With R=%u, CH=%u, Frames=%u, Periods=%u.\r\n", rate, ch, frames, periods);
    playback_handle = init_playback (argv[1], rate, ch, frames, periods);
    exit (0);
}