Print hardware capabilities of ALSA device

alsa-query.c

/*
 * alsa-query.c - print hardware capabilities of ALSA device
 *
 * compile with: gcc -o alsa-query alsa-query.c -lasound
 */

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

#define ARRAY_SIZE(a) (sizeof(a) / sizeof *(a))

static const snd_pcm_access_t accesses[] = {
    SND_PCM_ACCESS_MMAP_INTERLEAVED,
    SND_PCM_ACCESS_MMAP_NONINTERLEAVED,
    SND_PCM_ACCESS_MMAP_COMPLEX,
    SND_PCM_ACCESS_RW_INTERLEAVED,
    SND_PCM_ACCESS_RW_NONINTERLEAVED,
};

static const snd_pcm_format_t formats[] = {
    SND_PCM_FORMAT_S8,
    SND_PCM_FORMAT_U8,
    SND_PCM_FORMAT_S16_LE,
    SND_PCM_FORMAT_S16_BE,
    SND_PCM_FORMAT_U16_LE,
    SND_PCM_FORMAT_U16_BE,
    SND_PCM_FORMAT_S24_LE,
    SND_PCM_FORMAT_S24_BE,
    SND_PCM_FORMAT_U24_LE,
    SND_PCM_FORMAT_U24_BE,
    SND_PCM_FORMAT_S32_LE,
    SND_PCM_FORMAT_S32_BE,
    SND_PCM_FORMAT_U32_LE,
    SND_PCM_FORMAT_U32_BE,
    SND_PCM_FORMAT_FLOAT_LE,
    SND_PCM_FORMAT_FLOAT_BE,
    SND_PCM_FORMAT_FLOAT64_LE,
    SND_PCM_FORMAT_FLOAT64_BE,
    SND_PCM_FORMAT_IEC958_SUBFRAME_LE,
    SND_PCM_FORMAT_IEC958_SUBFRAME_BE,
    SND_PCM_FORMAT_MU_LAW,
    SND_PCM_FORMAT_A_LAW,
    SND_PCM_FORMAT_IMA_ADPCM,
    SND_PCM_FORMAT_MPEG,
    SND_PCM_FORMAT_GSM,
    SND_PCM_FORMAT_SPECIAL,
    SND_PCM_FORMAT_S24_3LE,
    SND_PCM_FORMAT_S24_3BE,
    SND_PCM_FORMAT_U24_3LE,
    SND_PCM_FORMAT_U24_3BE,
    SND_PCM_FORMAT_S20_3LE,
    SND_PCM_FORMAT_S20_3BE,
    SND_PCM_FORMAT_U20_3LE,
    SND_PCM_FORMAT_U20_3BE,
    SND_PCM_FORMAT_S18_3LE,
    SND_PCM_FORMAT_S18_3BE,
    SND_PCM_FORMAT_U18_3LE,
    SND_PCM_FORMAT_U18_3BE,
};

static const unsigned int rates[] = {
    5512,
    8000,
    11025,
    16000,
    22050,
    32000,
    44100,
    48000,
    64000,
    88200,
    96000,
    176400,
    192000,
};

int main(int argc, char *argv[])
{
    const char *device_name = "hw";
    snd_pcm_t *pcm;
    snd_pcm_hw_params_t *hw_params;
    unsigned int i;
    unsigned int min, max;
    int any_rate;
    int err;

    if (argc > 1)
        device_name = argv[1];

    err = snd_pcm_open(&pcm, device_name, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
    if (err < 0) {
        fprintf(stderr, "cannot open device '%s': %s\n", device_name, snd_strerror(err));
        return 1;
    }

    snd_pcm_hw_params_alloca(&hw_params);
    err = snd_pcm_hw_params_any(pcm, hw_params);
    if (err < 0) {
        fprintf(stderr, "cannot get hardware parameters: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }

    printf("Device: %s (type: %s)\n", device_name, snd_pcm_type_name(snd_pcm_type(pcm)));

    printf("Access types:");
    for (i = 0; i < ARRAY_SIZE(accesses); ++i) {
        if (!snd_pcm_hw_params_test_access(pcm, hw_params, accesses[i]))
            printf(" %s", snd_pcm_access_name(accesses[i]));
    }
    putchar('\n');

    printf("Formats:");
    for (i = 0; i < ARRAY_SIZE(formats); ++i) {
        if (!snd_pcm_hw_params_test_format(pcm, hw_params, formats[i]))
            printf(" %s", snd_pcm_format_name(formats[i]));
    }
    putchar('\n');

    err = snd_pcm_hw_params_get_channels_min(hw_params, &min);
    if (err < 0) {
        fprintf(stderr, "cannot get minimum channels count: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    err = snd_pcm_hw_params_get_channels_max(hw_params, &max);
    if (err < 0) {
        fprintf(stderr, "cannot get maximum channels count: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    printf("Channels:");
    for (i = min; i <= max; ++i) {
        if (!snd_pcm_hw_params_test_channels(pcm, hw_params, i))
            printf(" %u", i);
    }
    putchar('\n');

    err = snd_pcm_hw_params_get_rate_min(hw_params, &min, NULL);
    if (err < 0) {
        fprintf(stderr, "cannot get minimum rate: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    err = snd_pcm_hw_params_get_rate_max(hw_params, &max, NULL);
    if (err < 0) {
        fprintf(stderr, "cannot get maximum rate: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    printf("Sample rates:");
    if (min == max)
        printf(" %u", min);
    else if (!snd_pcm_hw_params_test_rate(pcm, hw_params, min + 1, 0))
        printf(" %u-%u", min, max);
    else {
        any_rate = 0;
        for (i = 0; i < ARRAY_SIZE(rates); ++i) {
            if (!snd_pcm_hw_params_test_rate(pcm, hw_params, rates[i], 0)) {
                any_rate = 1;
                printf(" %u", rates[i]);
            }
        }
        if (!any_rate)
            printf(" %u-%u", min, max);
    }
    putchar('\n');

    err = snd_pcm_hw_params_get_period_time_min(hw_params, &min, NULL);
    if (err < 0) {
        fprintf(stderr, "cannot get minimum period time: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    err = snd_pcm_hw_params_get_period_time_max(hw_params, &max, NULL);
    if (err < 0) {
        fprintf(stderr, "cannot get maximum period time: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    printf("Interrupt interval: %u-%u us\n", min, max);

    err = snd_pcm_hw_params_get_buffer_time_min(hw_params, &min, NULL);
    if (err < 0) {
        fprintf(stderr, "cannot get minimum buffer time: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    err = snd_pcm_hw_params_get_buffer_time_max(hw_params, &max, NULL);
    if (err < 0) {
        fprintf(stderr, "cannot get maximum buffer time: %s\n", snd_strerror(err));
        snd_pcm_close(pcm);
        return 1;
    }
    printf("Buffer size: %u-%u us\n", min, max);

    snd_pcm_close(pcm);
    return 0;
}