Simple Audio Recording Code Sample Options

[darkeye]

Hi,

I'm new to MacOS programming, but have considerable background in different UNIX systems. I'm trying to port my project, DarkIce to MacOS. For this, I need to be able to simply record audio from an audio device. More precisely:

• open the audio device
• configure for appropriate parameters (e.g. 44.1kHz, 16 bit, 2 channel, PCM recording)
• read from the device
• close the device

for example, on Solaris / OpenBSD / NetBSD, the following code achieves just this:

CODE

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <sys/audioio.h>

#define FILE_NAME "/dev/audio"
#define SAMPLE_RATE 22050
#define CHANNEL 2
#define BITS_PER_SAMPLE 16
#define BUF_SIZE 4

int main(int argc, char **argv) {
   int             fd;
   audio_info_t    audioInfo;
   unsigned char   buf[BUF_SIZE];
   unsigned int    len = BUF_SIZE;
   ssize_t         ret;

   fd = open( FILE_NAME, O_RDONLY);

   AUDIO_INITINFO( &audioInfo);
   audioInfo.record.sample_rate = SAMPLE_RATE;
   audioInfo.record.channels    = CHANNEL;
   audioInfo.record.precision   = BITS_PER_SAMPLE;
   audioInfo.record.encoding    = AUDIO_ENCODING_LINEAR;

   if ( ioctl(fd, AUDIO_SETINFO, &audioInfo) ) {
       printf("can't set audio info, error: %d\n", errno);
   }

   ret = read(fd, buf, len);

   printf("%d returned by read\n", ret);
   if ( ret == -1 ) {
       printf("error code %d\n", errno);
   }

   close(fd);

   return 0;
}

What I hear is that MacOS uses a callback pattern to access audio data from the sound card. if so, probably I'm looking for a sample that does:

• initialize the whole thing
• set the audio parameters (e.g. 44.1kHz 16 bit stereo PCM recording)
• register my callback function
• shut down

Can anyone help me?