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code.delx.au - pulseaudio/blob - src/pulse/volume.h
5 This file is part of PulseAudio.
7 Copyright 2004-2006 Lennart Poettering
8 Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
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.
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.
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
28 #include <pulse/cdecl.h>
29 #include <pulse/gccmacro.h>
30 #include <pulse/sample.h>
31 #include <pulse/channelmap.h>
33 /** \page volume Volume Control
35 * \section overv_sec Overview
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
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.
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.
48 * \section calc_sec Calculations
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:
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()
57 * For simple multiplication, pa_sw_volume_multiply() and
58 * pa_sw_cvolume_multiply() can be used.
60 * Calculations can only be reliably performed on software volumes
61 * as it is commonly unknown what scale hardware volumes relate to.
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
69 * \section conv_sec Convenience Functions
71 * To handle the pa_cvolume structure, the PulseAudio library provides a
72 * number of convenienc functions:
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
84 * \li pa_cvolume_reset() - Set all channels of a pa_cvolume structure to a
86 * \li pa_cvolume_mute() - Set all channels of a pa_cvolume structure to a
88 * \li pa_cvolume_avg() - Return the average volume of all channels.
89 * \li pa_cvolume_snprint() - Pretty print a pa_cvolume structure.
93 * Constants and routines for volume handling */
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
;
104 /** Normal volume (100%) */
105 #define PA_VOLUME_NORM ((pa_volume_t) 0x10000U)
107 /** Muted volume (0%) */
108 #define PA_VOLUME_MUTED ((pa_volume_t) 0U)
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 */
116 /** Return non-zero when *a == *b */
117 int pa_cvolume_equal ( const pa_cvolume
* a
, const pa_cvolume
* b
) PA_GCC_PURE
;
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)
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)
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
);
128 /** Maximum length of the strings returned by pa_cvolume_snprint() */
129 #define PA_CVOLUME_SNPRINT_MAX 64
131 /** Pretty print a volume structure */
132 char * pa_cvolume_snprint ( char * s
, size_t l
, const pa_cvolume
* c
);
134 /** Return the average volume of all channels */
135 pa_volume_t
pa_cvolume_avg ( const pa_cvolume
* a
) PA_GCC_PURE
;
137 /** Return the maximum volume of all channels. \since 0.9.12 */
138 pa_volume_t
pa_cvolume_max ( const pa_cvolume
* a
) PA_GCC_PURE
;
140 /** Return TRUE when the passed cvolume structure is valid, FALSE otherwise */
141 int pa_cvolume_valid ( const pa_cvolume
* v
) PA_GCC_PURE
;
143 /** Return non-zero if the volume of all channels is equal to the specified value */
144 int pa_cvolume_channels_equal_to ( const pa_cvolume
* a
, pa_volume_t v
) PA_GCC_PURE
;
146 /** Return 1 if the specified volume has all channels muted */
147 #define pa_cvolume_is_muted(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_MUTED)
149 /** Return 1 if the specified volume has all channels on normal level */
150 #define pa_cvolume_is_norm(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_NORM)
152 /** Multiply two volumes specifications, return the result. This uses PA_VOLUME_NORM as neutral element of multiplication. This is only valid for software volumes! */
153 pa_volume_t
pa_sw_volume_multiply ( pa_volume_t a
, pa_volume_t b
) PA_GCC_CONST
;
155 /** Multiply to per-channel volumes and return the result in *dest. This is only valid for software volumes! */
156 pa_cvolume
* pa_sw_cvolume_multiply ( pa_cvolume
* dest
, const pa_cvolume
* a
, const pa_cvolume
* b
);
158 /** Convert a decibel value to a volume. This is only valid for software volumes! */
159 pa_volume_t
pa_sw_volume_from_dB ( double f
) PA_GCC_CONST
;
161 /** Convert a volume to a decibel value. This is only valid for software volumes! */
162 double pa_sw_volume_to_dB ( pa_volume_t v
) PA_GCC_CONST
;
164 /** Convert a linear factor to a volume. This is only valid for software volumes! */
165 pa_volume_t
pa_sw_volume_from_linear ( double v
) PA_GCC_CONST
;
167 /** Convert a volume to a linear factor. This is only valid for software volumes! */
168 double pa_sw_volume_to_linear ( pa_volume_t v
) PA_GCC_CONST
;
171 #define PA_DECIBEL_MININFTY ((double) -INFINITY)
173 /** This value is used as minus infinity when using pa_volume_{to,from}_dB(). */
174 #define PA_DECIBEL_MININFTY ((double) -200.0)
177 /** Remap a volume from one channel mapping to a different channel mapping. \since 0.9.12 */
178 pa_cvolume
* pa_cvolume_remap ( pa_cvolume
* v
, pa_channel_map
* from
, pa_channel_map
* to
);