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

   1 #ifndef foovolumehfoo
   2 #define foovolumehfoo
   3
   4 /***
   5   This file is part of PulseAudio.
   6
   7   Copyright 2004-2006 Lennart Poettering
   8   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   9
  10   PulseAudio is free software; you can redistribute it and/or modify
  11   it under the terms of the GNU Lesser General Public License as published
  12   by the Free Software Foundation; either version 2 of the License,
  13   or (at your option) any later version.
  14
  15   PulseAudio is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with PulseAudio; if not, write to the Free Software
  22   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  23   USA.
  24 ***/
  25
  26 #include <inttypes.h>
  27
  28 #include <pulse/cdecl.h>
  29 #include <pulse/gccmacro.h>
  30 #include <pulse/sample.h>
  31 #include <pulse/channelmap.h>
  32
  33 /** \page volume Volume Control
  34  *
  35  * \section overv_sec Overview
  36  *
  37  * Sinks, sources, sink inputs and samples can all have their own volumes.
  38  * To deal with these, The PulseAudio libray contains a number of functions
  39  * that ease handling.
  40  *
  41  * The basic volume type in PulseAudio is the \ref pa_volume_t type. Most of
  42  * the time, applications will use the aggregated pa_cvolume structure that
  43  * can store the volume of all channels at once.
  44  *
  45  * Volumes commonly span between muted (0%), and normal (100%). It is possible
  46  * to set volumes to higher than 100%, but clipping might occur.
  47  *
  48  * \section calc_sec Calculations
  49  *
  50  * The volumes in PulseAudio are logarithmic in nature and applications
  51  * shouldn't perform calculations with them directly. Instead, they should
  52  * be converted to and from either dB or a linear scale:
  53  *
  54  * \li dB - pa_sw_volume_from_dB() / pa_sw_volume_to_dB()
  55  * \li Linear - pa_sw_volume_from_linear() / pa_sw_volume_to_linear()
  56  *
  57  * For simple multiplication, pa_sw_volume_multiply() and
  58  * pa_sw_cvolume_multiply() can be used.
  59  *
  60  * Calculations can only be reliably performed on software volumes
  61  * as it is commonly unknown what scale hardware volumes relate to.
  62  *
  63  * The functions described above are only valid when used with
  64  * software volumes. Hence it is usually a better idea to treat all
  65  * volume values as opaque with a range from PA_VOLUME_MUTE (0%) to
  66  * PA_VOLUME_NORM (100%) and to refrain from any calculations with
  67  * them.
  68  *
  69  * \section conv_sec Convenience Functions
  70  *
  71  * To handle the pa_cvolume structure, the PulseAudio library provides a
  72  * number of convenienc functions:
  73  *
  74  * \li pa_cvolume_valid() - Tests if a pa_cvolume structure is valid.
  75  * \li pa_cvolume_equal() - Tests if two pa_cvolume structures are identical.
  76  * \li pa_cvolume_channels_equal_to() - Tests if all channels of a pa_cvolume
  77  *                             structure have a given volume.
  78  * \li pa_cvolume_is_muted() - Tests if all channels of a pa_cvolume
  79  *                             structure are muted.
  80  * \li pa_cvolume_is_norm() - Tests if all channels of a pa_cvolume structure
  81  *                            are at a normal volume.
  82  * \li pa_cvolume_set() - Set all channels of a pa_cvolume structure to a
  83  *                        certain volume.
  84  * \li pa_cvolume_reset() - Set all channels of a pa_cvolume structure to a
  85  *                          normal volume.
  86  * \li pa_cvolume_mute() - Set all channels of a pa_cvolume structure to a
  87  *                         muted volume.
  88  * \li pa_cvolume_avg() - Return the average volume of all channels.
  89  * \li pa_cvolume_snprint() - Pretty print a pa_cvolume structure.
  90  */
  91
  92 /** \file
  93  * Constants and routines for volume handling */
  94
  95 PA_C_DECL_BEGIN
  96
  97 /** Volume specification:
  98  *  PA_VOLUME_MUTED: silence;
  99  * < PA_VOLUME_NORM: decreased volume;
 100  *   PA_VOLUME_NORM: normal volume;
 101  * > PA_VOLUME_NORM: increased volume */
 102 typedef uint32_t pa_volume_t;
 103
 104 /** Normal volume (100%) */
 105 #define PA_VOLUME_NORM ((pa_volume_t) 0x10000U)
 106
 107 /** Muted volume (0%) */
 108 #define PA_VOLUME_MUTED ((pa_volume_t) 0U)
 109
 110 /** A structure encapsulating a per-channel volume */
 111 typedef struct pa_cvolume {
 112     uint8_t channels;                     /**< Number of channels */
 113     pa_volume_t values[PA_CHANNELS_MAX];  /**< Per-channel volume  */
 114 } pa_cvolume;
 115
 116 /** Return non-zero when *a == *b */
 117 int pa_cvolume_equal(const pa_cvolume *a, const pa_cvolume *b) PA_GCC_PURE;
 118
 119 /** Set the volume of all channels to PA_VOLUME_NORM */
 120 #define pa_cvolume_reset(a, n) pa_cvolume_set((a), (n), PA_VOLUME_NORM)
 121
 122 /** Set the volume of all channels to PA_VOLUME_MUTED */
 123 #define pa_cvolume_mute(a, n) pa_cvolume_set((a), (n), PA_VOLUME_MUTED)
 124
 125 /** Set the volume of all channels to the specified parameter */
 126 pa_cvolume* pa_cvolume_set(pa_cvolume *a, unsigned channels, pa_volume_t v);
 127
 128 /** Maximum length of the strings returned by pa_cvolume_snprint() */
 129 #define PA_CVOLUME_SNPRINT_MAX 64
 130
 131 /** Pretty print a volume structure */
 132 char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c);
 133
 134 /** Return the average volume of all channels */
 135 pa_volume_t pa_cvolume_avg(const pa_cvolume *a) PA_GCC_PURE;
 136
 137 /** Return TRUE when the passed cvolume structure is valid, FALSE otherwise */
 138 int pa_cvolume_valid(const pa_cvolume *v) PA_GCC_PURE;
 139
 140 /** Return non-zero if the volume of all channels is equal to the specified value */
 141 int pa_cvolume_channels_equal_to(const pa_cvolume *a, pa_volume_t v) PA_GCC_PURE;
 142
 143 /** Return 1 if the specified volume has all channels muted */
 144 #define pa_cvolume_is_muted(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_MUTED)
 145
 146 /** Return 1 if the specified volume has all channels on normal level */
 147 #define pa_cvolume_is_norm(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_NORM)
 148
 149 /** Multiply two volumes specifications, return the result. This uses PA_VOLUME_NORM as neutral element of multiplication. This is only valid for software volumes! */
 150 pa_volume_t pa_sw_volume_multiply(pa_volume_t a, pa_volume_t b) PA_GCC_CONST;
 151
 152 /** Multiply to per-channel volumes and return the result in *dest. This is only valid for software volumes! */
 153 pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b);
 154
 155 /** Convert a decibel value to a volume. This is only valid for software volumes! */
 156 pa_volume_t pa_sw_volume_from_dB(double f) PA_GCC_CONST;
 157
 158 /** Convert a volume to a decibel value. This is only valid for software volumes! */
 159 double pa_sw_volume_to_dB(pa_volume_t v) PA_GCC_CONST;
 160
 161 /** Convert a linear factor to a volume. This is only valid for software volumes! */
 162 pa_volume_t pa_sw_volume_from_linear(double v) PA_GCC_CONST;
 163
 164 /** Convert a volume to a linear factor. This is only valid for software volumes! */
 165 double pa_sw_volume_to_linear(pa_volume_t v) PA_GCC_CONST;
 166
 167 #ifdef INFINITY
 168 #define PA_DECIBEL_MININFTY ((double) -INFINITY)
 169 #else
 170 /** This value is used as minus infinity when using pa_volume_{to,from}_dB(). */
 171 #define PA_DECIBEL_MININFTY ((double) -200.0)
 172 #endif
 173
 174 /** Remap a volume from one channel mapping to a different channel mapping. \since 0.9.12 */
 175 pa_cvolume *pa_cvolume_remap(pa_cvolume *v, pa_channel_map *from, pa_channel_map *to);
 176
 177 PA_C_DECL_END
 178
 179 #endif