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Open Sound System OSS 4.x Programmer's Guide

playtgt.c

Description

Copyright (C) 4Front Technologies, 2002-2007. Released under GPLv2/CDDL.

This program demonstrates the new ioctl call interface used to control the play target selection.

The first command line argument is the audio device (/dev/dsp#). If there are no other arguments then the available choices will be printed. If the second argument is "-" then the current setting will be printed. Finally the source can be changed by giving it's name as the second argument.

Please not that the change may stay in effect even after closing the device. However equally well it's possible that the device returns back to some default source. There is no way to predict how the device will behave and the application must not expect any particular behaviour.

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <soundcard.h>
#include <time.h>

int
main (int argc, char *argv[])
{
  int fd, i, src;
  oss_mixer_enuminfo ei;

  if (argc < 2)
    {
      fprintf (stderr, "Usage: %s dspdev\n", argv[0]);
      exit (-1);
    }

  if ((fd = open (argv[1], O_WRONLY, 0)) == -1)
    {
      perror (argv[1]);
      exit (-1);
    }

  if (ioctl (fd, SNDCTL_DSP_GET_PLAYTGT_NAMES, &ei) == -1)
    {
      perror ("SNDCTL_DSP_GET_PLAYTGT_NAMES");
      exit (-1);
    }

  if (argc == 2)
    {
      for (i = 0; i < ei.nvalues; i++)
	printf ("Play target #%d = '%s'\n", i, ei.strings + ei.strindex[i]);
      exit (0);
    }

  if (strcmp (argv[2], "?") == 0 || strcmp (argv[2], "-") == 0)
    {
      if (ioctl (fd, SNDCTL_DSP_GET_PLAYTGT, &src) == -1)
	{
	  perror ("SNDCTL_DSP_GET_PLAYTGT");
	  exit (-1);
	}

      printf ("Current play target is #%d\n", src);
      printf ("Current play target is #%d (%s)\n",
	      src, ei.strings + ei.strindex[src]);
      exit (0);
    }

  src = 0;

  for (i = 0; i < ei.nvalues; i++)
    {
      if (strcmp (argv[2], ei.strings + ei.strindex[i]) == 0)
	{
	  if (ioctl (fd, SNDCTL_DSP_SET_PLAYTGT, &src) == -1)
	    {
	      perror ("SNDCTL_DSP_SET_PLAYTGT");
	      exit (-1);
	    }

	  exit (0);
	}

      src++;
    }

  fprintf (stderr, "What?\n");
  exit (-1);
}

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