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Copyright (C) 4Front Technologies, 2002-2004. Released under GPLv2/CDDL.
This program is as simple as possible example for using the new mixer API of OSS 4.0 (and later) from applications. It shows how to read or change the settings. Please read the OSS API Developer's Manual for more info about this API.
This mixer interface is designed to ne "human readable". The idea is that the mixer program just shows whatever controls are available and lets the user to adjust them as he/she likes.
Please note that the control names and numbers are fully dynamic. There are some control names such as "spdif.enable" that are used by several different drivers. It's relatively safe to assume that such controls have always the same meaning. However there is no list of such control names available at this moment. Even this kind of controls are supported just by some of the devices (some devices just don't have that feature).
Most control names are 100% non-portable between devices. In addition some settings may be available depending on the configuration.
Applications using this mixer interface must not assume that certain controls are always available or that they have exactly defined meanings.
This program can be run without any command line arguments to list the available controls and their values. The mixer device number (0 by default) can be given on the command line.
Another way is to give the mixer number, control ame and value on the command line (mixext 1 spdif.enable 1).
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <soundcard.h>
#include <time.h>
#include <errno.h>
static int mixer_dev = 0; /* Change this to access another mixer device */
static int mixerfd = -1;
typedef struct
{
int num;
char *name;
} name_ent;
#define TYPE_ENTRY(x) {x, #x}
name_ent type_names[] = {
TYPE_ENTRY (MIXT_DEVROOT),
TYPE_ENTRY (MIXT_GROUP),
TYPE_ENTRY (MIXT_ONOFF),
TYPE_ENTRY (MIXT_MUTE),
TYPE_ENTRY (MIXT_ENUM),
TYPE_ENTRY (MIXT_MONOSLIDER),
TYPE_ENTRY (MIXT_STEREOSLIDER),
TYPE_ENTRY (MIXT_MESSAGE),
TYPE_ENTRY (MIXT_MONOVU),
TYPE_ENTRY (MIXT_STEREOVU),
TYPE_ENTRY (MIXT_MONOPEAK),
TYPE_ENTRY (MIXT_STEREOPEAK),
TYPE_ENTRY (MIXT_RADIOGROUP),
TYPE_ENTRY (MIXT_MARKER),
TYPE_ENTRY (MIXT_VALUE),
TYPE_ENTRY (MIXT_HEXVALUE),
TYPE_ENTRY (MIXT_MONODB),
TYPE_ENTRY (MIXT_STEREODB),
TYPE_ENTRY (MIXT_SLIDER),
TYPE_ENTRY (MIXT_3D),
TYPE_ENTRY (MIXT_MONOSLIDER16),
TYPE_ENTRY (MIXT_STEREOSLIDER16),
{-1, NULL}
};
static char *
mixt_name (int num)
{
int i;
i = 0;
while (type_names[i].num != -1)
{
if (type_names[i].num == num)
return type_names[i].name;
i++;
}
return "Unknown type";
}
void
list_controls (int mixer_dev)
{
int i, n, nn = 0;
oss_mixext ext;
int marker_seen = 0;
n = mixer_dev;
if (ioctl (mixerfd, SNDCTL_MIX_NREXT, &n) == -1)
{
perror ("SNDCTL_MIX_NREXT");
if (errno == EINVAL)
fprintf (stderr, "Error: OSS version 3.9 or later is required\n");
return;
}
printf ("%d mixer controls available (including ordinary mixer controls)\n",
n);
for (i = 0; i < n; i++)
{
oss_mixer_value val;
ext.dev = mixer_dev;
ext.ctrl = i;
if (ioctl (mixerfd, SNDCTL_MIX_EXTINFO, &ext) == -1)
{
if (errno == EINVAL)
{
fprintf (stderr, "SNDCTL_MIX_EXTINFO failed\n");
fprintf (stderr,
"This is almost certainly caused by a too old or new OSS version.\n");
return;
}
perror ("SNDCTL_MIX_EXTINFO");
return;
}
if (ext.type == MIXT_MARKER)
{
marker_seen = 1;
continue;
}
else if (!marker_seen)
continue;
val.dev = mixer_dev;
val.ctrl = i;
val.timestamp = ext.timestamp;
val.value = 0;
if (ext.type != MIXT_DEVROOT && ext.type != MIXT_GROUP
&& ext.type != MIXT_MARKER)
if (ioctl (mixerfd, SNDCTL_MIX_READ, &val) == -1)
{
perror ("SNDCTL_MIX_READ");
val.value = 0xffffffff;
}
printf ("%3d: \"%s\" (\"%s\"), parent %d\n", i, ext.extname, ext.id,
ext.parent);
printf (" Type %d (%s), value %d (0x%08x) (max %d)\n", ext.type,
mixt_name (ext.type), val.value, val.value, ext.maxvalue);
printf (" Update counter %d\n", ext.update_counter);
nn++;
}
printf ("%d controls accessible by this program\n", nn);
}
int
set_control (int mixer_dev, char *name, int value)
{
int i, n;
oss_mixext ext;
int marker_seen = 0;
n = mixer_dev;
if (ioctl (mixerfd, SNDCTL_MIX_NREXT, &n) == -1)
{
perror ("SNDCTL_MIX_NREXT");
if (errno == EINVAL)
fprintf (stderr, "Error: OSS version 3.9 or later is required\n");
return -4;
}
for (i = 0; i < n; i++)
{
oss_mixer_value val;
ext.dev = mixer_dev;
ext.ctrl = i;
if (ioctl (mixerfd, SNDCTL_MIX_EXTINFO, &ext) == -1)
{
perror ("SNDCTL_MIX_EXTINFO");
return -1;
}
if (ext.type == MIXT_MARKER)
{
marker_seen = 1;
continue;
}
else if (!marker_seen)
continue;
if (strcmp (ext.extname, name) != 0) /* No match */
continue;
if (!(ext.flags & MIXF_WRITEABLE))
return -2;
val.dev = mixer_dev;
val.ctrl = i;
val.timestamp = ext.timestamp;
val.value = value;
if (ioctl (mixerfd, SNDCTL_MIX_WRITE, &val) == -1)
{
perror ("SNDCTL_MIX_WRITE");
return -3;
}
return 1;
}
return 0;
}
int
main (int argc, char *argv[])
{
char *devmixer;
if ((devmixer=getenv("OSS_MIXERDEV"))==NULL)
devmixer = "/dev/mixer";
if (argc > 1)
mixer_dev = atoi (argv[1]);
if ((mixerfd = open (devmixer, O_RDWR, 0)) == -1)
{
perror (devmixer);
exit (-1);
}
if (argc > 3)
{
int val;
val = atoi (argv[3]);
if (set_control (mixer_dev, argv[2], val) > 0)
{
fprintf (stderr, "OK\n");
}
else
{
fprintf (stderr, "Failed!!!\n");
}
exit (0);
}
list_controls (mixer_dev);
exit (0);
}