linux pcm接口调试

sudo apt-get update
sudo apt-get install alsa-tools alsa-utils
sudo alsactl init

alsamixer # 使用alsamixer调整音频设置

pulseaudio -k # 停止PulseAudio服务
pulseaudio --start # 启动PulseAudio服务

echo "options snd-hda-intel model=dell-headset-multi" | sudo tee -a /etc/modprobe.d/alsa-base.conf
sudo update-initramfs -u

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

int main() {
    int err;
    snd_pcm_t *handle;
    snd_pcm_hw_params_t *params;
    unsigned int rate = 44100;
    int dir;
    char *buffer;
    int size;

    // Open PCM device for playback.
    if ((err = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
        fprintf(stderr, "Cannot open audio device (%s)\n", snd_strerror(err));
        exit(1);
    }

    // Allocate a hardware parameters object.
    snd_pcm_hw_params_alloca(&params);

    // Fill it in with default values.
    snd_pcm_hw_params_any(handle, params);

    // Set the desired hardware parameters.
    snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
    snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);
    snd_pcm_hw_params_set_rate_near(handle, params, &rate, &dir);
    snd_pcm_hw_params_set_channels(handle, params, 2);

    // Apply the hardware parameters.
    if ((err = snd_pcm_hw_params(handle, params)) < 0) {
        fprintf(stderr, "Cannot set hardware parameters (%s)\n", snd_strerror(err));
        exit(1);
    }

    // Allocate buffer to hold single period.
    snd_pcm_hw_params_get_period_size(params, &size, &dir);
    buffer = (char *) malloc(size * 4);

    // Fill the buffer with some data.
    for (int i = 0; i < size; ++i) {
        buffer[i * 4] = 0;       // Left channel
        buffer[i * 4 + 1] = 0;   // Right channel
        buffer[i * 4 + 2] = 0;   // Left channel
        buffer[i * 4 + 3] = 0;   // Right channel
    }

    // Write the data to the device.
    while (1) {
        if ((err = snd_pcm_writei(handle, buffer, size)) != size) {
            fprintf(stderr, "Write error: %s\n", snd_strerror(err));
            break;
        }
    }

    // Close the PCM device.
    snd_pcm_close(handle);
    free(buffer);

    return 0;
}

gcc -o pcm_test pcm_test.c -lasound
./pcm_test