code.delx.au - pulseaudio/blob - src/pulse/volume.h

   1 #ifndef foovolumehfoo
   2 #define foovolumehfoo
   3
   4 /* $Id$ */
   5
   6 /***
   7   This file is part of PulseAudio.
   8
   9   PulseAudio is free software; you can redistribute it and/or modify
  10   it under the terms of the GNU Lesser General Public License as published
  11   by the Free Software Foundation; either version 2 of the License,
  12   or (at your option) any later version.
  13
  14   PulseAudio is distributed in the hope that it will be useful, but
  15   WITHOUT ANY WARRANTY; without even the implied warranty of
  16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17   General Public License for more details.
  18
  19   You should have received a copy of the GNU Lesser General Public License
  20   along with PulseAudio; if not, write to the Free Software
  21   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  22   USA.
  23 ***/
  24
  25 #include <inttypes.h>
  26 #include <pulse/cdecl.h>
  27 #include <pulse/sample.h>
  28
  29 /** \page volume Volume Control
  30  *
  31  * \section overv_sec Overview
  32  *
  33  * Sinks, sources, sink inputs and samples can all have their own volumes.
  34  * To deal with these, The PulseAudio libray contains a number of functions
  35  * that ease handling.
  36  *
  37  * The basic volume type in PulseAudio is the \ref pa_volume_t type. Most of
  38  * the time, applications will use the aggregated pa_cvolume structure that
  39  * can store the volume of all channels at once.
  40  *
  41  * Volumes commonly span between muted (0%), and normal (100%). It is possible
  42  * to set volumes to higher than 100%, but clipping might occur.
  43  *
  44  * \section calc_sec Calculations
  45  *
  46  * The volumes in PulseAudio are logarithmic in nature and applications
  47  * shouldn't perform calculations with them directly. Instead, they should
  48  * be converted to and from either dB or a linear scale:
  49  *
  50  * \li dB - pa_sw_volume_from_dB() / pa_sw_volume_to_dB()
  51  * \li Linear - pa_sw_volume_from_linear() / pa_sw_volume_to_linear()
  52  *
  53  * For simple multiplication, pa_sw_volume_multiply() and
  54  * pa_sw_cvolume_multiply() can be used.
  55  *
  56  * Calculations can only be reliably performed on software volumes
  57  * as it is commonly unknown what scale hardware volumes relate to.
  58  *
  59  * The functions described above are only valid when used with
  60  * software volumes. Hence it is usually a better idea to treat all
  61  * volume values as opaque with a range from PA_VOLUME_MUTE (0%) to
  62  * PA_VOLUME_NORM (100%) and to refrain from any calculations with
  63  * them.
  64  *
  65  * \section conv_sec Convenience Functions
  66  *
  67  * To handle the pa_cvolume structure, the PulseAudio library provides a
  68  * number of convenienc functions:
  69  *
  70  * \li pa_cvolume_valid() - Tests if a pa_cvolume structure is valid.
  71  * \li pa_cvolume_equal() - Tests if two pa_cvolume structures are identical.
  72  * \li pa_cvolume_channels_equal_to() - Tests if all channels of a pa_cvolume
  73  *                             structure have a given volume.
  74  * \li pa_cvolume_is_muted() - Tests if all channels of a pa_cvolume
  75  *                             structure are muted.
  76  * \li pa_cvolume_is_norm() - Tests if all channels of a pa_cvolume structure
  77  *                            are at a normal volume.
  78  * \li pa_cvolume_set() - Set all channels of a pa_cvolume structure to a
  79  *                        certain volume.
  80  * \li pa_cvolume_reset() - Set all channels of a pa_cvolume structure to a
  81  *                          normal volume.
  82  * \li pa_cvolume_mute() - Set all channels of a pa_cvolume structure to a
  83  *                         muted volume.
  84  * \li pa_cvolume_avg() - Return the average volume of all channels.
  85  * \li pa_cvolume_snprint() - Pretty print a pa_cvolume structure.
  86  */
  87
  88 /** \file
  89  * Constants and routines for volume handling */
  90
  91 PA_C_DECL_BEGIN
  92
  93 /** Volume specification:
  94  *  PA_VOLUME_MUTED: silence;
  95  * < PA_VOLUME_NORM: decreased volume;
  96  *   PA_VOLUME_NORM: normal volume;
  97  * > PA_VOLUME_NORM: increased volume */
  98 typedef uint32_t pa_volume_t;
  99
 100 /** Normal volume (100%) */
 101 #define PA_VOLUME_NORM (0x10000)
 102
 103 /** Muted volume (0%) */
 104 #define PA_VOLUME_MUTED (0)
 105
 106 /** A structure encapsulating a per-channel volume */
 107 typedef struct pa_cvolume {
 108     uint8_t channels;                     /**< Number of channels */
 109     pa_volume_t values[PA_CHANNELS_MAX];  /**< Per-channel volume  */
 110 } pa_cvolume;
 111
 112 /** Return non-zero when *a == *b */
 113 int pa_cvolume_equal(const pa_cvolume *a, const pa_cvolume *b);
 114
 115 /** Set the volume of all channels to PA_VOLUME_NORM */
 116 #define pa_cvolume_reset(a, n) pa_cvolume_set((a), (n), PA_VOLUME_NORM)
 117
 118 /** Set the volume of all channels to PA_VOLUME_MUTED */
 119 #define pa_cvolume_mute(a, n) pa_cvolume_set((a), (n), PA_VOLUME_MUTED)
 120
 121 /** Set the volume of all channels to the specified parameter */
 122 pa_cvolume* pa_cvolume_set(pa_cvolume *a, unsigned channels, pa_volume_t v);
 123
 124 /** Maximum length of the strings returned by pa_cvolume_snprint() */
 125 #define PA_CVOLUME_SNPRINT_MAX 64
 126
 127 /** Pretty print a volume structure */
 128 char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c);
 129
 130 /** Return the average volume of all channels */
 131 pa_volume_t pa_cvolume_avg(const pa_cvolume *a);
 132
 133 /** Return TRUE when the passed cvolume structure is valid, FALSE otherwise */
 134 int pa_cvolume_valid(const pa_cvolume *v);
 135
 136 /** Return non-zero if the volume of all channels is equal to the specified value */
 137 int pa_cvolume_channels_equal_to(const pa_cvolume *a, pa_volume_t v);
 138
 139 /** Return 1 if the specified volume has all channels muted */
 140 #define pa_cvolume_is_muted(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_MUTED)
 141
 142 /** Return 1 if the specified volume has all channels on normal level */
 143 #define pa_cvolume_is_norm(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_NORM)
 144
 145 /** Multiply two volumes specifications, return the result. This uses PA_VOLUME_NORM as neutral element of multiplication. This is only valid for software volumes! */
 146 pa_volume_t pa_sw_volume_multiply(pa_volume_t a, pa_volume_t b);
 147
 148 /** Multiply to per-channel volumes and return the result in *dest. This is only valid for software volumes! */
 149 pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b);
 150
 151 /** Convert a decibel value to a volume. This is only valid for software volumes! \since 0.4 */
 152 pa_volume_t pa_sw_volume_from_dB(double f);
 153
 154 /** Convert a volume to a decibel value. This is only valid for software volumes! \since 0.4 */
 155 double pa_sw_volume_to_dB(pa_volume_t v);
 156
 157 /** Convert a linear factor to a volume. This is only valid for software volumes! \since 0.8 */
 158 pa_volume_t pa_sw_volume_from_linear(double v);
 159
 160 /** Convert a volume to a linear factor. This is only valid for software volumes! \since 0.8 */
 161 double pa_sw_volume_to_linear(pa_volume_t v);
 162
 163 #ifdef INFINITY
 164 #define PA_DECIBEL_MININFTY (-INFINITY)
 165 #else
 166 /** This value is used as minus infinity when using pa_volume_{to,from}_dB(). \since 0.4 */
 167 #define PA_DECIBEL_MININFTY (-200)
 168 #endif
 169
 170 PA_C_DECL_END
 171
 172 #endif