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