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Multi channel audio test.
This program is intended to test playback of 16 bit samples using 4 or more channels at 48000 Hz. The program plays sine wave pulses sequentially on channels 0 to N-1.
Arguments:
1: Number of channelts (default is 8). 2: Audio device (/dev/dsp by default). 3-N: Options -b Bypass virtual mixer -r Raw mode (disables automatic sample rate/format conversions)
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <soundcard.h>
static int sinedata[48] = {
0, 4276, 8480, 12539, 16383, 19947, 23169, 25995,
28377, 30272, 31650, 32486, 32767, 32486, 31650, 30272,
28377, 25995, 23169, 19947, 16383, 12539, 8480, 4276,
0, -4276, -8480, -12539, -16383, -19947, -23169, -25995,
-28377, -30272, -31650, -32486, -32767, -32486, -31650, -30272,
-28377, -25995, -23169, -19947, -16383, -12539, -8480, -4276
};
int
main (int argc, char *argv[])
{
char *dev = "/dev/dsp";
int fd, l, i, n = 0, ch, p = 0, phase = 0, arg, channels, srate, thisch = 0;
int tick = 0;
int nch = 8;
int bypass_vmix=0;
int disable_format_conversions=0;
short buf[1024];
if (argc > 1)
if (sscanf (argv[1], "%d", &nch) != 1)
nch = 2;
if (argc > 2)
dev = argv[2];
for (i=3;i<argc;i++)
if (argv[i][0]=='-')
switch (argv[i][1])
{
case 'b': /* Bypass virtual mixer */
bypass_vmix = O_EXCL;
break;
case 'r': /* Use raw mode (disable automatic format conversions) */
disable_format_conversions=1;
break;
}
if ((fd = open (dev, O_WRONLY|bypass_vmix, 0)) == -1)
{
perror (dev);
exit (-1);
}
if (disable_format_conversions)
{
arg=0;
ioctl(fd, SNDCTL_DSP_COOKEDMODE, &arg);
}
arg = nch;
if (ioctl (fd, SNDCTL_DSP_CHANNELS, &arg) == -1)
perror ("SNDCTL_DSP_CHANNELS");
channels = arg;
fprintf (stderr, "Channels %d\n", arg);
arg = AFMT_S16_NE;
if (ioctl (fd, SNDCTL_DSP_SETFMT, &arg) == -1)
perror ("SNDCTL_DSP_SETFMT");
fprintf (stderr, "Format %x\n", arg);
arg = 48000;
if (ioctl (fd, SNDCTL_DSP_SPEED, &arg) == -1)
perror ("SNDCTL_DSP_SPEED");
printf ("Using sampling rate %d\n", arg);
srate = arg;
while (1)
{
for (ch = 0; ch < channels; ch++)
{
if (ch == thisch)
{
buf[p] = sinedata[phase];
phase = (phase + 1 + (ch / 2)) % 48;
if (phase == 0 && tick > 10 * channels)
{
thisch = (thisch + 1) % channels;
tick = 0;
}
}
else
buf[p] = 0;
p++;
if (p >= sizeof (buf) / 2)
{
if (write (fd, buf, p * 2) != p * 2)
perror ("write");
p = 0;
tick++;
}
}
n++;
}
exit (0);
}