microphone level meter?

Hi all,

I'm trying to implement a simple program that measures the ambient noise
level, using the ipaq's microphone. The readings I get from /dev/dsp
don't really make sense, though, most of them are 0 and the few others
seem random: what am I doing wrong? I experimented with different values
for speed, channels, and sample format: help!:

Source code:

int sample = AFMT_U8;
int channels = 2;
int speed = 16000;
int ret;
unsigned char buf[1024];
int dsp = open("/dev/dsp", O_RDONLY);
if (dsp!=-1) {
   ioctl(dsp, SNDCTL_DSP_SPEED, &speed);
   ioctl(dsp, SNDCTL_DSP_CHANNELS, &channels);
   ioctl(dsp, SNDCTL_DSP_SETFMT, &sample);
   ret = read(dsp, buf, sizeof(buf));
   for (int i=0; i<ret; i++)
       fifo.add(buf[i]);
   close(dsp);
}
printf("the noise volume is: %f", fifo.get_volume());

Cheers,

        Kristof.
Received on Fri Jan 24 2003 - 13:15:02 EST