linux下用C语言实现MP3播放器代码

这里提供一个简单的基于 ALSA 库的 MP3 播放器代码，仅供参考：

#include <alsa/asoundlib.h>
#include <mpg123.h>

#define BUFFER_SIZE 4096

// 初始化 ALSA 音频设备
snd_pcm_t *init_alsa(char *device_name, unsigned int *sample_rate, unsigned int *channels, snd_pcm_uframes_t *frames)
{
    int err;
    snd_pcm_t *handle;
    snd_pcm_hw_params_t *params;
    unsigned int val;

    // 打开音频设备
    if ((err = snd_pcm_open(&handle, device_name, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
        printf("Error opening PCM device %s: %s\n", device_name, snd_strerror(err));
        return NULL;
    }

    // 初始化硬件参数
    snd_pcm_hw_params_alloca(&params);
    if ((err = snd_pcm_hw_params_any(handle, params)) < 0) {
        printf("Error initializing hardware parameters: %s\n", snd_strerror(err));
        return NULL;
    }

    // 设置采样率
    if ((err = snd_pcm_hw_params_set_rate_resample(handle, params, 1)) < 0) {
        printf("Error setting resample: %s\n", snd_strerror(err));
        return NULL;
    }
    val = *sample_rate;
    if ((err = snd_pcm_hw_params_set_rate_near(handle, params, &val, 0)) < 0) {
        printf("Error setting sample rate: %s\n", snd_strerror(err));
        return NULL;
    }
    if (val != *sample_rate) {
        printf("Warning: sample rate %d Hz not supported, using %d Hz instead.\n", *sample_rate, val);
        *sample_rate = val;
    }

    // 设置声道数
    val = *channels;
    if ((err = snd_pcm_hw_params_set_channels_near(handle, params, &val)) < 0) {
        printf("Error setting channels: %s\n", snd_strerror(err));
        return NULL;
    }
    if (val != *channels) {
        printf("Warning: channels count %d not supported, using %d instead.\n", *channels, val);
        *channels = val;
    }

    // 设置采样格式
    if ((err = snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE)) < 0) {
        printf("Error setting sample format: %s\n", snd_strerror(err));
        return NULL;
    }

    // 设置周期大小
    if ((err = snd_pcm_hw_params_get_period_size(params, frames, 0)) < 0) {
        printf("Error getting period size: %s\n", snd_strerror(err));
        return NULL;
    }

    // 设置硬件参数
    if ((err = snd_pcm_hw_params(handle, params)) < 0) {
        printf("Error setting hardware parameters: %s\n", snd_strerror(err));
        return NULL;
    }

    return handle;
}

// 播放 MP3 文件
void play_mp3(char *file_name, snd_pcm_t *handle, unsigned int sample_rate, unsigned int channels, snd_pcm_uframes_t frames)
{
    int err;
    mpg123_handle *mh;
    unsigned char buffer[BUFFER_SIZE];
    size_t bytes_read;
    off_t samples;

    // 初始化 mpg123 解码库
    mpg123_init();
    mh = mpg123_new(NULL, &err);
    mpg123_open(mh, file_name);
    mpg123_getformat(mh, &sample_rate, &channels, NULL);

    // 循环读取并播放音频数据
    while (1) {
        mpg123_read(mh, buffer, BUFFER_SIZE, &bytes_read);
        if (bytes_read == 0) break;
        samples = bytes_read / (channels * 2);
        if ((err = snd_pcm_writei(handle, buffer, samples)) < 0) {
            printf("Error playing audio: %s\n", snd_strerror(err));
            break;
        }
    }

    // 释放资源
    mpg123_close(mh);
    mpg123_delete(mh);
    mpg123_exit();
}

int main(int argc, char *argv[])
{
    unsigned int sample_rate = 44100;  // 采样率
    unsigned int channels = 2;  // 声道数
    snd_pcm_uframes_t frames = 512;  // 周期大小
    snd_pcm_t *handle;

    // 初始化 ALSA 设备
    handle = init_alsa("default", &sample_rate, &channels, &frames);
    if (handle == NULL) {
        printf("Failed to initialize ALSA device.\n");
        return -1;
    }

    // 播放 MP3 文件
    play_mp3(argv[1], handle, sample_rate, channels, frames);

    // 关闭 ALSA 设备
    snd_pcm_drain(handle);
    snd_pcm_close(handle);

    return 0;
}

这份代码仅实现了 MP3 文件的播放，没有实现 GUI 界面和播放控制等功能。如果需要实现更完整的 MP3 播放器，还需要进一步开发。