Linux下的音频采集与回放

以下假设你对ioctl已有一定的认识及了解
sndtools.h
代码:
#ifndef SNDTOOLS_H #define SNDTOOLS_H #include <Linux/soundcard.h> #define FMT8BITS AFMT_S8_LE #define FMT16BITS AFMT_S16_LE #define FMT8K 8000 #define FMT16K 16000 #define FMT22K 22000 #define FMT44K 44000 #define MONO 1 #define STERO 2 #ifndef VAR_STATIC extern int devfd; extern int CapMask; #endif //ifndef VAR_STATIC //Open sound device, return 1 if open sUCcess //else return 0 int OpenSnd(); //Close sound device int CloseSnd(); //Set record or playback format, return 1 if success //else return 0 int SetFormat(int bits, int hz); //Set record or playback channel, return 1 if success //else return 1 int SetChannel(int chn); //Record int Record(char *buf, int size); //Playback int Play(char *buf, int size); #endif //ifndef SNDTOOLS_H sndtools.c 代码: #include <stdio.h> #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> #include <string.h> #define VAR_STATIC #include "sndtools.h" int devfd = 0; /* * Open Sound device * Return 1 if success, else return 0. */ int OpenSnd(/* add by new version */int nWhich) { if(devfd > 0) close(devfd); devfd = open("/dev/dsp", O_RDWR); if(devfd < 0) return 0; return 1; } /* * Close Sound device * return 1 if success, else return 0. */ int CloseSnd(/* add by new version */int nWhich) { close(devfd); devfd = 0; return 1; } /* * Set Record an Playback format * return 1 if success, else return 0. * bits -- FMT8BITS(8bits), FMT16BITS(16bits) * hz -- FMT8K(8000HZ), FMT16K(16000HZ), FMT22K(22000HZ), FMT44K(44000HZ) */ int SetFormat(int bits, int hz) { int tmp = bits; if( -1 == ioctl(devfd, SNDCTL_DSP_SETFMT, &tmp)) { #ifdef DEBUG_WARN printf("Set fmt to s16_little faile:%d//n", nWhich); #endif return 0; } tmp = hz; if( -1 == ioctl(devfd, SNDCTL_DSP_SPEED, &tmp)) { #ifdef DEBUG_WARN printf("Set speed to %d:%d//n", hz, nWhich); #endif return 0; } return 1; } /* * Set Sound Card Channel * return 1 if success, else return 0. * chn -- MONO, STERO */ int SetChannel(int chn) { int tmp = chn; if(-1 == ioctl(devfd, SNDCTL_DSP_CHANNELS, &tmp)) { #ifdef DEBUG_WARN printf("Set Audio Channel faile:%d//n", nWhich); #endif return 0; } return 1; } /* * Record * return numbers of byte for read. */ int Record(char *buf, int size) { return read(devfd, buf, size); } /* * Playback * return numbers of byte for write. */ int Play(char *buf, int size) { return write(devfd, buf, size); }

test.c

代码:

// A sample to test record and playback. #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include "sndtools.h" int main() { char *buf; int dwSize; if(!OpenSnd()) { printf("Open sound device error!//n"); exit(-1); } SetFormat(FMT16BITS, FMT8K, WAVOUTDEV); SetChannel(MONO, WAVOUTDEV); buf = (char *)malloc(320); if(buf == NULL) exit(-1); for(int i = 0; i <1000; i++) { dwSize = Record(buf, 640); dwSize = Play(buf, dwSize); } exit 1; }