直接贴代码：
#include <stdio.h> #include <stdlib.h> #include "playWav.h" #include <alsa/asoundlib.h> #include <iostream> using namespace std; void playSound(const char* filepath) { ; int i; int ret; int buf[128]; unsigned int val; int dir=0; char *buffer; int size; snd_pcm_uframes_t frames; snd_pcm_uframes_t periodsize; snd_pcm_t *playback_handle;//PCM设备句柄pcm.h snd_pcm_hw_params_t *hw_params;//硬件信息和PCM流配置 /* if (argc != 2) { printf("error: alsa_play_test [music name]\n"); exit(1); }*/ cout << "start playing... wav from: /" << filepath << endl; FILE *fp = fopen(filepath, "rb"); if(fp == NULL) return 0; fseek(fp, 100, SEEK_SET); //1. 打开PCM，最后一个参数为0意味着标准配置 ret = snd_pcm_open(&playback_handle, "default", SND_PCM_STREAM_PLAYBACK, 0); if (ret < 0) { perror("snd_pcm_open"); exit(1); } //2. 分配snd_pcm_hw_params_t结构体 ret = snd_pcm_hw_params_malloc(&hw_params); if (ret < 0) { perror("snd_pcm_hw_params_malloc"); exit(1); } //3. 初始化hw_params ret = snd_pcm_hw_params_any(playback_handle, hw_params); if (ret < 0) { perror("snd_pcm_hw_params_any"); exit(1); } //4. 初始化访问权限 ret = snd_pcm_hw_params_set_access(playback_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED); if (ret < 0) { perror("snd_pcm_hw_params_set_access"); exit(1); } //5. 初始化采样格式SND_PCM_FORMAT_U8,8位 ret = snd_pcm_hw_params_set_format(playback_handle, hw_params, SND_PCM_FORMAT_S16_LE); if (ret < 0) { perror("snd_pcm_hw_params_set_format"); exit(1); } //6. 设置采样率，如果硬件不支持我们设置的采样率，将使用最接近的 //val = 44100,有些录音采样频率固定为8KHz val = 16000; ret = snd_pcm_hw_params_set_rate_near(playback_handle, hw_params, &val, &dir); if (ret < 0) { perror("snd_pcm_hw_params_set_rate_near"); exit(1); } //7. 设置通道数量 1 ret = snd_pcm_hw_params_set_channels(playback_handle, hw_params, 1); if (ret < 0) { perror("snd_pcm_hw_params_set_channels"); exit(1); } /* Set period size to 32 frames. */ frames = 32; periodsize = frames ; ret = snd_pcm_hw_params_set_buffer_size_near(playback_handle, hw_params, &periodsize); if (ret < 0) { printf("Unable to set buffer size %li : %s\n", frames * 2, snd_strerror(ret)); } periodsize /= 2; ret = snd_pcm_hw_params_set_period_size_near(playback_handle, hw_params, &periodsize, 0); if (ret < 0) { printf("Unable to set period size %li : %s\n", periodsize, snd_strerror(ret)); } //8. 设置hw_params ret = snd_pcm_hw_params(playback_handle, hw_params); if (ret < 0) { perror("snd_pcm_hw_params"); exit(1); } /* Use a buffer large enough to hold one period */ snd_pcm_hw_params_get_period_size(hw_params, &frames, &dir); size = frames * 2; /* 2 bytes/sample, 2 channels */ buffer = (char *) malloc(size); // fprintf(stderr, // "size = %d\n", // size); while (1) { ret = fread(buffer, 1, size, fp); if(ret == 0) { // fprintf(stderr, "end of file on input\n"); break; } else if (ret != size) { } //9. 写音频数据到PCM设备 while(ret = snd_pcm_writei(playback_handle, buffer, frames)<0) { usleep(2000); if (ret == -EPIPE) { /* EPIPE means underrun */ fprintf(stderr, "underrun occurred\n"); //完成硬件参数设置，使设备准备好 snd_pcm_prepare(playback_handle); } else if (ret < 0) { fprintf(stderr, "error from writei: %s\n", snd_strerror(ret)); } } } //10. 关闭PCM设备句柄 snd_pcm_close(playback_handle); }
