//linux下ALSA录制声音的源程序 //欧德浪18年2月2日整理
/* Use the newer ALSA API */
#define ALSA_PCM_NEW_HW_PARAMS_API
#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 = 1;
int rate = 8000;
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 main()
{
long loops;
int rc;
int size;
snd_pcm_t *rec_handle;
snd_pcm_hw_params_t *rec_params;
unsigned int val;
int dir;
snd_pcm_uframes_t frames;
char *buffer;
WAVEHDR wavheader;
int total_len = 0;
FILE *fp_rec = fopen("rec.wav", "wb");
if(fp_rec==NULL)
{
return 0;
}
wav_start_write(fp_rec, &wavheader);
/* Open PCM device for recording (capture). */
rc = snd_pcm_open(&rec_handle, "default",
SND_PCM_STREAM_CAPTURE, 0);
if (rc < 0) {
fprintf(stderr,
"unable to open pcm device: %s\n",
snd_strerror(rc));
exit(1);
}
/* Allocate a hardware parameters object. */
snd_pcm_hw_params_alloca(&rec_params);
/* Fill it in with default values. */
snd_pcm_hw_params_any(rec_handle, rec_params);
/* Set the desired hardware parameters. */
/* Interleaved mode */
snd_pcm_hw_params_set_access(rec_handle, rec_params,
SND_PCM_ACCESS_RW_INTERLEAVED);
/* Signed 16-bit little-endian format */
snd_pcm_hw_params_set_format(rec_handle, rec_params,
SND_PCM_FORMAT_S16_LE);
/* Two channels (stereo) */
snd_pcm_hw_params_set_channels(rec_handle, rec_params, 1);
/* 44100 bits/second sampling rate (CD quality) */
val = 8000;
snd_pcm_hw_params_set_rate_near(rec_handle, rec_params,
&val, &dir);
/* Set period size to 32 frames. */
frames = 32;
snd_pcm_hw_params_set_period_size_near(rec_handle,
rec_params, &frames, &dir);
/* Write the parameters to the driver */
rc = snd_pcm_hw_params(rec_handle, rec_params);
if (rc < 0)
{
fprintf(stderr,
"unable to set hw parameters: %s\n",
snd_strerror(rc));
exit(1);
}
/* Use a buffer large enough to hold one period */
snd_pcm_hw_params_get_period_size(rec_params, &frames, &dir);
size = frames * 2; /* 2 bytes/sample, 2 channels */
buffer = (char *) malloc(size);
/* We want to loop for 5 seconds */
snd_pcm_hw_params_get_period_time(rec_params, &val, &dir);
loops = 2000;
while (loops-- > 0)
{
rc = snd_pcm_readi(rec_handle, buffer, frames);
if (rc == -EPIPE)
{
/* EPIPE means overrun */
fprintf(stderr, "overrun occurred\n");
snd_pcm_prepare(rec_handle);
}
else if (rc < 0)
{
fprintf(stderr, "error from read: %s\n", snd_strerror(rc));
}
else if (rc != (int)frames)
{
fprintf(stderr, "short read, read %d frames\n", rc);
}
rc = fwrite(buffer, 1, size, fp_rec);
total_len += size;
printf("#\n");
if (rc != size)
fprintf(stderr,"short write: wrote %d bytes\n", rc);
}
wav_stop_write(fp_rec, &wavheader, total_len);
snd_pcm_drain(rec_handle);
snd_pcm_close(rec_handle);
free(buffer);
fclose(fp_rec);
return 0;
}
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