wmix/include/mixer.h

   1 /* WMix 3.0 -- a mixer using the OSS mixer API.
   2  * Copyright (C) 2000, 2001
   3  *      Daniel Richard G. <skunk@mit.edu>,
   4  *      timecop <timecop@japan.co.jp>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 /* WMVolume mixer interface
  22  *
  23  * Some notes:
  24  *
  25  * - The volume argument is a floating-point value between 0 (no sound) and
  26  *   1 (full sound) inclusively.
  27  *
  28  * - The balance argument is a floating-point value betwen -1 (full left)
  29  *   and 1 (full right) inclusively. A value of 0 indicates centered sound.
  30  *   If the device does not natively support a balance parameter, use the
  31  *   lr_to_vb() and vb_to_lr() functions in misc.c.
  32  *
  33  * - The volume and balance arguments passed to these functions, given that
  34  *   they are (usually 32-bit) floating-point values, may be capable of
  35  *   specifying the audio parameters at a finer resolution than the
  36  *   hardware itself. However, the mixer driver must not quantize the
  37  *   volume and balance levels returned by the mixer_get_*() routines.
  38  *
  39  *   Example: Suppose the mixer device supports specifying the volume as an
  40  *   integer in the range of 0 to 100. If mixer_set_volume() is called with
  41  *   an argument of 0.7351, then the device will be set to a volume of 74,
  42  *   yet subsequent calls to mixer_get_volume() (assuming mixer state has
  43  *   not changed since) will return 0.7351. Only if the mixer state is
  44  *   changed by another program (that, say, sets the volume to 51) is the
  45  *   value returned by this interface quantized (in such a case returning
  46  *   0.51).
  47  *
  48  *   The reason why this quantization must be avoided whenever possible is
  49  *   that otherwise, a large number of minuscule increases to the volume
  50  *   level will have no cumulative effect. Calling mixer_set_volume_rel()
  51  *   ten thousand times with an argument of 0.0001 should successfully
  52  *   increase the volume to its maximum, even if the device actually
  53  *   supports only 64 discrete volume levels.
  54  *
  55  * - Muting must occur independently of the volume level.
  56  */
  57
  58 extern void (*mixer_init)(const char *mixer_device,
  59                           bool verbose,
  60                           const char *exclude[]);
  61 extern bool (*mixer_is_changed)(void);
  62 extern int (*mixer_get_channel_count)(void);
  63 extern int (*mixer_get_channel)(void);
  64 extern const char *(*mixer_get_channel_name)(void);
  65 extern const char *(*mixer_get_short_name)(void);
  66 extern void (*mixer_set_channel)(int channel);
  67 extern void (*mixer_set_channel_rel)(int delta_channel);
  68 extern float (*mixer_get_volume)(void);
  69 extern void (*mixer_set_volume)(float volume);
  70 extern void (*mixer_set_volume_rel)(float delta_volume);
  71 extern float (*mixer_get_balance)(void);
  72 extern void (*mixer_set_balance)(float balance);
  73 extern void (*mixer_set_balance_rel)(float delta_balance);
  74 extern void (*mixer_toggle_mute)(void);
  75 extern void (*mixer_toggle_rec)(void);
  76 extern bool (*mixer_is_muted)(void);
  77 extern bool (*mixer_is_stereo)(void);
  78 extern bool (*mixer_is_rec)(void);
  79 extern bool (*mixer_can_rec)(void);
  80 extern bool (*is_exclude)(const char *short_name,
  81                           const char *exclude[]);
  82 extern void (*mixer_tick)(void);