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// This small util discovers your audio driver's behaviour
//#define OUTBURST 512
//#define OUTBURST 4096
#define MAX_OUTBURST 32768
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/soundcard.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
// Returns current time in microseconds
unsigned int GetTimer(){
struct timeval tv;
struct timezone tz;
// float s;
gettimeofday(&tv,&tz);
// s=tv.tv_usec;s*=0.000001;s+=tv.tv_sec;
return (tv.tv_sec*1000000+tv.tv_usec);
}
static unsigned char a_buffer[MAX_OUTBURST];
void inline print_info(int audio_fd){
#if 1
audio_buf_info zz;
ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &zz);
printf("Status: %3d/%d (%d byte/frag) free: %6d\n",
zz.fragments, zz.fragstotal, zz.fragsize, zz.bytes);
#endif
}
int main(){
int audio_buffer_size=0;
int r;
int xxx=1024*2;
int audio_fd;
char *dsp="/dev/dsp";
unsigned int t0,t1,t2;
int outburst;
audio_fd=open(dsp, O_WRONLY);
if(audio_fd<0){
printf("Can't open audio device %s\n",dsp);
return 1;
}
// ioctl(audio_fd, SNDCTL_DSP_RESET, NULL);
// ioctl(audio_fd, SNDCTL_DSP_RESET, NULL);
r=AFMT_S16_LE;ioctl (audio_fd, SNDCTL_DSP_SETFMT, &r);
r=1; ioctl (audio_fd, SNDCTL_DSP_STEREO, &r);
r=44100; if(ioctl (audio_fd, SNDCTL_DSP_SPEED, &r)==-1)
printf("audio_setup: your card doesn't support %d Hz samplerate\n",r);
r=0; ioctl (audio_fd, SNDCTL_DSP_GETBLKSIZE, &r);
printf("fragment size = %d\n",r);
outburst=r; if(outburst>4096) outburst=4096;
print_info(audio_fd);
t0=t1=GetTimer();
while(xxx-->0){
char c='B';
fd_set rfds;
struct timeval tv;
FD_ZERO(&rfds); FD_SET(audio_fd,&rfds);
tv.tv_sec=0; tv.tv_usec = 0;
// if(select(audio_fd+1, NULL, &rfds, NULL, &tv)) c=' ';
print_info(audio_fd);
r=0; ioctl (audio_fd, SNDCTL_DSP_GETODELAY, &r); printf("delay = %d\n",r);
r=write(audio_fd,a_buffer,outburst);
t2=GetTimer();
if(r<0) printf("Error writting to device\n"); else
if(r==0) printf("EOF writting to device???\n"); else {
printf("%c %6.3f %6.3f [%6d] writting %3d of %3d bytes in %7d us\n",c,
(float)audio_buffer_size/(44100.0f*4.0f),(float)(t1-t0)*0.000001f,
audio_buffer_size,r,outburst,t2-t1);
audio_buffer_size+=r;
}
t1=t2;
}
close(audio_fd);
return 0;
}
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