sound1.c

其中sound.c 用于录音和回放。其中特别需要注意的是:1。目前声卡似乎不能打开全双工

/*
 * sound.c
 */
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <stdio.h>
#include <linux/soundcard.h>

#define LENGTH 3    /* 存储秒数 */
#define RATE 44100   /* 采样频率 */		
#define SIZE 16      /* 量化位数 */
#define CHANNELS 1  /* 声道数目 */ /*0:单声道 1：立体声 */

/* 用于保存数字音频数据的内存缓冲区 */
unsigned char buf[LENGTH*RATE*SIZE*(CHANNELS+1)/8];

int main()
{
  int fd; /* 声音设备的文件描述符 */
  int waveid; /*保存wav声音文件描述符 */
  int arg; /* 用于ioctl调用的参数 */
  int status;   /* 系统调用的返回值 */

  /* 打开声音设备 */
  fd = open("/dev/dsp", O_RDONLY);
  if (fd < 0) {
    perror("open of /dev/dsp failed");
    exit(1);
  }
  
  waveid = open("test.wav",O_RDWR);
  if (waveid < 0) {
  	perror("open test.wav failed");
  	exit(1);
  }

  /* 设置采样时的量化位数 */
  arg = SIZE;
  status = ioctl(fd, SOUND_PCM_WRITE_BITS, &arg);
  if (status == -1)
    perror("SOUND_PCM_WRITE_BITS ioctl failed");
  if (arg != SIZE)
    perror("unable to set sample size");

  /* 设置采样时的声道数目 */
  arg = CHANNELS; 
  status = ioctl(fd, SOUND_PCM_WRITE_CHANNELS, &arg);
  if (status == -1)
    perror("SOUND_PCM_WRITE_CHANNELS ioctl failed");
  if (arg != CHANNELS)
    perror("unable to set number of channels");

  /* 设置采样时的采样频率 */
  arg = RATE;
  status = ioctl(fd, SOUND_PCM_WRITE_RATE, &arg);
  perror("SNDCTL_DSP_SPEED");
	
  if (status == -1)  	
    perror("SOUND_PCM_WRITE_WRITE ioctl failed");

  /* 循环，直到按下Control-C */
  //while (1) {
    printf("Say something:\n");
    status = read(fd, buf, sizeof(buf)); /* 录音 */
    if (status != sizeof(buf))
      perror("read wrong number of bytes");
		
		
		
		/*printf("Press any key to playback:"); */
   // getchar();

    printf("coding:\n");
    status = write(waveid, buf, sizeof(buf)); /* 回放 */
    if (status != sizeof(buf))
    perror("wrote wrong number of bytes");

    /* 在继续录音前等待回放结束 */
   // status = ioctl(fd, SOUND_PCM_SYNC, 0); 
    //if (status == -1)
    //  perror("SOUND_PCM_SYNC ioctl failed");
      
    //printf("Press any key to go again:");
    //getchar(); 
  //}
}