165 lines
4.7 KiB
C
165 lines
4.7 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <alsa/asoundlib.h>
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void check_and_set_max_volume()
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{
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FILE *fp;
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char buffer[256];
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int volume_left = -1;
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int speaker_on = 0;
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// 检查 PCM 音量
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fp = popen("amixer get PCM | grep 'Front Left'", "r");
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if (fp)
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{
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while (fgets(buffer, sizeof(buffer), fp))
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{
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if (sscanf(buffer, " Front Left: %d", &volume_left) == 1)
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{
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break;
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}
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}
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pclose(fp);
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}
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if (volume_left == -1)
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{
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printf("无法获取音量信息\n");
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}
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else if (volume_left < 192)
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{
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printf("当前音量为 %d，设置为最大...\n", volume_left);
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system("amixer set PCM 192");
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}
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else
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{
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printf("音量已是最大（%d）\n", volume_left);
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}
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// 检查扬声器是否开启
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fp = popen("amixer get Speaker | grep 'Mono:'", "r");
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if (fp)
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{
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while (fgets(buffer, sizeof(buffer), fp))
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{
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if (strstr(buffer, "[on]"))
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{
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speaker_on = 1;
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break;
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}
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}
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pclose(fp);
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}
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if (!speaker_on)
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{
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printf("扬声器未打开，正在开启...\n");
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system("amixer set Speaker unmute");
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}
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else
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{
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printf("扬声器已开启\n");
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}
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}
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int main(int argc, char *argv[])
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{
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check_and_set_max_volume();
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const char *device = "hw:0,0"; // 要使用的 ALSA 设备
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const char *filename = "001.wav"; // WAV 文件路径
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snd_pcm_t *pcm_handle;
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snd_pcm_hw_params_t *params;
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unsigned int sample_rate = 44100; // 采样率（需与 WAV 文件一致）
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int pcm, dir;
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snd_pcm_uframes_t frames;
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FILE *file;
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char *buffer;
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int buffer_size;
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// 打开音频文件
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file = fopen(filename, "rb");
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if (!file)
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{
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perror("Unable to open audio file");
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return 1;
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}
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// 跳过标准 WAV 头部（44 字节），如果你的音频文件已经是纯 PCM 数据可以注释掉此行
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fseek(file, 44, SEEK_SET);
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// 打开 PCM 设备
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if ((pcm = snd_pcm_open(&pcm_handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0)
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{
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fprintf(stderr, "Unable to open PCM device %s: %s\n", device, snd_strerror(pcm));
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fclose(file);
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return 1;
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}
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// 分配并初始化硬件参数对象
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snd_pcm_hw_params_alloca(¶ms);
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snd_pcm_hw_params_any(pcm_handle, params);
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snd_pcm_hw_params_set_access(pcm_handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
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snd_pcm_hw_params_set_format(pcm_handle, params, SND_PCM_FORMAT_S16_LE);
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snd_pcm_hw_params_set_channels(pcm_handle, params, 2);
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snd_pcm_hw_params_set_rate_near(pcm_handle, params, &sample_rate, &dir);
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// 应用硬件参数
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if ((pcm = snd_pcm_hw_params(pcm_handle, params)) < 0)
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{
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fprintf(stderr, "Unable to set hardware parameters: %s\n", snd_strerror(pcm));
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snd_pcm_close(pcm_handle);
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fclose(file);
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return 1;
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}
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// 获取每个周期（period）的帧数，并据此计算缓冲区大小
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snd_pcm_hw_params_get_period_size(params, &frames, &dir);
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buffer_size = frames * 2 /*bytes per sample*/ * 2 /*channels*/;
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buffer = (char *)malloc(buffer_size);
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if (!buffer)
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{
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fprintf(stderr, "Unable to allocate buffer\n");
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snd_pcm_close(pcm_handle);
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fclose(file);
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return 1;
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}
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// 无限循环播放
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while (1)
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{
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size_t bytes_read = fread(buffer, 1, buffer_size, file);
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if (bytes_read == 0)
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{
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// 已经读到文件末尾，重新回到数据区的起始位置（跳过头部）
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fseek(file, 44, SEEK_SET);
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continue;
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}
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// 计算本次要写入的“帧”数，如果最后一块数据不足一个完整周期，按实际读到的字节数计算
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snd_pcm_uframes_t frames_to_deliver = bytes_read / (2 * 2);
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// 写入 PCM
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int ret = snd_pcm_writei(pcm_handle, buffer, frames_to_deliver);
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if (ret == -EPIPE)
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{
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// 缓冲区下溢，重启 PCM 设备
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snd_pcm_prepare(pcm_handle);
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}
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else if (ret < 0)
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{
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fprintf(stderr, "Playback error: %s\n", snd_strerror(ret));
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}
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// 如果写入的帧数小于需要的，可以在这里处理（可选）
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}
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// 下面的代码理论上永远不会执行到，但为了完整性保留
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free(buffer);
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snd_pcm_drain(pcm_handle);
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snd_pcm_close(pcm_handle);
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fclose(file);
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return 0;
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}
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