Linux下基于alsa录制wav文件

#include "alsa/asoundlib.h"

/* this buffer holds the digitized audio */

//unsigned char buf[LENGTH*RATE*SIZE*CHANNELS/8];

typedef unsigned char  BYTE;

typedef unsigned short  WORD;

typedef unsigned int  DWORD;

typedef unsigned int  FOURCC;    /* a four character code */

/* flags for 'wFormatTag' field of WAVEFORMAT */

#define WAVE_FORMAT_PCM 1

/* MMIO macros */

#define mmioFOURCC(ch0, ch1, ch2, ch3) \

  ((DWORD)(BYTE)(ch0) | ((DWORD)(BYTE)(ch1) << 8) | \

  ((DWORD)(BYTE)(ch2) << 16) | ((DWORD)(BYTE)(ch3) << 24))

#define FOURCC_RIFF    mmioFOURCC ('R', 'I', 'F', 'F')

#define FOURCC_LIST    mmioFOURCC ('L', 'I', 'S', 'T')

#define FOURCC_WAVE    mmioFOURCC ('W', 'A', 'V', 'E')

#define FOURCC_FMT    mmioFOURCC ('f', 'm', 't', ' ')

#define FOURCC_DATA    mmioFOURCC ('d', 'a', 't', 'a')

typedef struct CHUNKHDR {

FOURCC ckid;        /* chunk ID */

DWORD dwSize;            /* chunk size */

} CHUNKHDR;

/* simplified Header for standard WAV files */

typedef struct WAVEHDR {

CHUNKHDR chkRiff;

FOURCC fccWave;

CHUNKHDR chkFmt;

WORD wFormatTag;      /* format type */

WORD nChannels;      /* number of channels (i.e. mono, stereo, etc.) */

DWORD nSamplesPerSec;  /* sample rate */

DWORD nAvgBytesPerSec; /* for buffer estimation */

WORD nBlockAlign;      /* block size of data */

WORD wBitsPerSample;

CHUNKHDR chkData;

} WAVEHDR;

#if BYTE_ORDER == BIG_ENDIAN

# define cpu_to_le32(x) SWAP4((x))

# define cpu_to_le16(x) SWAP2((x))

# define le32_to_cpu(x) SWAP4((x))

# define le16_to_cpu(x) SWAP2((x))

#else

# define cpu_to_le32(x) (x)

# define cpu_to_le16(x) (x)

# define le32_to_cpu(x) (x)

# define le16_to_cpu(x) (x)

#endif

static void wav_init_header(WAVEHDR *fileheader)

{

/* stolen from cdda2wav */

int nBitsPerSample = 16;

int channels      = 2;

int rate          = 44100;

unsigned long nBlockAlign = channels * ((nBitsPerSample + 7) / 8);

unsigned long nAvgBytesPerSec = nBlockAlign * rate;

unsigned long temp = /* data length */ 0 +

sizeof(WAVEHDR) - sizeof(CHUNKHDR);

fileheader->chkRiff.ckid    = cpu_to_le32(FOURCC_RIFF);

fileheader->fccWave        = cpu_to_le32(FOURCC_WAVE);

fileheader->chkFmt.ckid    = cpu_to_le32(FOURCC_FMT);

fileheader->chkFmt.dwSize  = cpu_to_le32(16);

fileheader->wFormatTag      = cpu_to_le16(WAVE_FORMAT_PCM);

fileheader->nChannels      = cpu_to_le16(channels);

fileheader->nSamplesPerSec  = cpu_to_le32(rate);

fileheader->nAvgBytesPerSec = cpu_to_le32(nAvgBytesPerSec);

fileheader->nBlockAlign    = cpu_to_le16(nBlockAlign);

fileheader->wBitsPerSample  = cpu_to_le16(nBitsPerSample);

fileheader->chkData.ckid    = cpu_to_le32(FOURCC_DATA);

fileheader->chkRiff.dwSize  = cpu_to_le32(temp);

fileheader->chkData.dwSize  = cpu_to_le32(0 /* data length */);

}

static void wav_start_write(FILE* fd, WAVEHDR *fileheader)

{

wav_init_header(fileheader);

fwrite(fileheader,1, sizeof(WAVEHDR), fd);

}

static void wav_stop_write(FILE* fd, WAVEHDR *fileheader, int wav_size)

{

unsigned long temp = wav_size + sizeof(WAVEHDR) - sizeof(CHUNKHDR);

fileheader->chkRiff.dwSize = cpu_to_le32(temp);

fileheader->chkData.dwSize = cpu_to_le32(wav_size);

fseek(fd,0,SEEK_SET);

  fwrite(fileheader,1, sizeof(WAVEHDR), fd);

}

int init_pcm_capture(snd_pcm_t **handle,snd_pcm_uframes_t *frame)

{

//1.定义pcm句柄

//snd_pcm_t *handle = NULL;

snd_pcm_hw_params_t *params = NULL;

//2.打开pcm设备---采集方式打开

//(SND_PCM_STREAM_CAPTURE:打开模式)

snd_pcm_open(handle, "default", SND_PCM_STREAM_CAPTURE, 0);

//3 分配参数空间， 设置默认参数

snd_pcm_hw_params_alloca(¶ms);

//分配空间

snd_pcm_hw_params_any(*handle, params);  //默认值

//4.设置交错模式

snd_pcm_hw_params_set_access(*handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);

//5设置量化

snd_pcm_hw_params_set_format(*handle, params, SND_PCM_FORMAT_S16_LE);

//6设置通道数据

snd_pcm_hw_params_set_channels(*handle, params, 2);

//7设置采样率

int val = 44100;

snd_pcm_hw_params_set_rate_near(*handle, params, &val,0);

//8把设置好的参数设置到pcm设备

snd_pcm_hw_params(*handle,params);

//9.分配一个周期空间

//获取一个周期的帧数

snd_pcm_hw_params_get_period_size(params, frame, 0);

}

int main(void)

{

WAVEHDR wavheader;

int total_len = 0;

int ret;

snd_pcm_t *handle = NULL;

snd_pcm_uframes_t frame = 0;

init_pcm_capture(&handle,&frame);

int size = frame * 4;//计算一个周期所需要的存储空间

unsigned char *buffer = malloc(size);//分配一个周期的空间

FILE *fp = fopen("rec.wav","wb");

wav_start_write(fp, &wavheader);

int t = (int)(44100 * 5.0)/frame;//计算1s内的周期

while(t --)

{

snd_pcm_readi(handle, buffer, frame);//采集一个周期数据

ret = fwrite(buffer,1,size,fp);

total_len += size;

if(ret != size)

{

printf("size is %d\n",size);

printf("short wrote:%d\n",size-ret);

printf("fwrite data error\n");

}

}

wav_stop_write(fp, &wavheader, total_len);

//销毁pcm句柄

snd_pcm_drain(handle);

//关闭pcm设备

snd_pcm_close(handle);

//释放堆空间（存储一个周期数据）

free(buffer);

fclose(fp);

return 0;

}