]>
code.delx.au - pulseaudio/blob - src/polyp/volume.h
181784f405f1c8ae3e78db419419086d0b815449
7 This file is part of polypaudio.
9 polypaudio 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.
14 polypaudio 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.
19 You should have received a copy of the GNU Lesser General Public License
20 along with polypaudio; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
26 #include <polyp/cdecl.h>
27 #include <polyp/sample.h>
29 /** \page volume Volume control
31 * \section overv_sec Overview
33 * Sinks, sources, sink inputs and samples can all have their own volumes.
34 * To deal with these, The Polypaudio libray contains a number of functions
37 * The basic volume type in Polypaudio 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.
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.
44 * \section calc_sec Calculations
46 * The volumes in Polypaudio 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:
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()
53 * For simple multiplication, pa_sw_volume_multiply() and
54 * pa_sw_cvolume_multiply() can be used.
56 * Calculations can only be reliably be performed on software volumes as
57 * it is commonly unknown what scale hardware volumes use.
59 * \section conv_sec Convenience functions
61 * To handle the pa_cvolume structure, the Polypaudio library provides a
62 * number of convenienc functions:
64 * \li pa_cvolume_valid() - Tests if a pa_cvolume structure is valid.
65 * \li pa_cvolume_equal() - Tests if two pa_cvolume structures are identical.
66 * \li pa_cvolume_channels_equal_to() - Tests if all channels of a pa_cvolume
67 * structure have a given volume.
68 * \li pa_cvolume_is_muted() - Tests if all channels of a pa_cvolume
69 * structure are muted.
70 * \li pa_cvolume_is_norm() - Tests if all channels of a pa_cvolume structure
71 * are at a normal volume.
72 * \li pa_cvolume_set() - Set all channels of a pa_cvolume structure to a
74 * \li pa_cvolume_reset() - Set all channels of a pa_cvolume structure to a
76 * \li pa_cvolume_mute() - Set all channels of a pa_cvolume structure to a
78 * \li pa_cvolume_avg() - Return the average volume of all channels.
79 * \li pa_cvolume_snprint() - Pretty print a pa_cvolume structure.
83 * Constants and routines for volume handling */
87 /** Volume specification:
88 * PA_VOLUME_MUTED: silence;
89 * < PA_VOLUME_NORM: decreased volume;
90 * PA_VOLUME_NORM: normal volume;
91 * > PA_VOLUME_NORM: increased volume */
92 typedef uint32_t pa_volume_t
;
94 /** Normal volume (100%) */
95 #define PA_VOLUME_NORM (0x10000)
97 /** Muted volume (0%) */
98 #define PA_VOLUME_MUTED (0)
100 /** A structure encapsulating a per-channel volume */
101 typedef struct pa_cvolume
{
102 uint8_t channels
; /**< Number of channels */
103 pa_volume_t values
[ PA_CHANNELS_MAX
]; /**< Per-channel volume */
106 /** Return non-zero when *a == *b */
107 int pa_cvolume_equal ( const pa_cvolume
* a
, const pa_cvolume
* b
);
109 /** Set the volume of all channels to PA_VOLUME_NORM */
110 #define pa_cvolume_reset(a, n) pa_cvolume_set((a), (n), PA_VOLUME_NORM)
112 /** Set the volume of all channels to PA_VOLUME_MUTED */
113 #define pa_cvolume_mute(a, n) pa_cvolume_set((a), (n), PA_VOLUME_MUTED)
115 /** Set the volume of all channels to the specified parameter */
116 pa_cvolume
* pa_cvolume_set ( pa_cvolume
* a
, unsigned channels
, pa_volume_t v
);
118 /** Maximum length of the strings returned by pa_cvolume_snprint() */
119 #define PA_CVOLUME_SNPRINT_MAX 64
121 /** Pretty print a volume structure */
122 char * pa_cvolume_snprint ( char * s
, size_t l
, const pa_cvolume
* c
);
124 /** Return the average volume of all channels */
125 pa_volume_t
pa_cvolume_avg ( const pa_cvolume
* a
);
127 /** Return TRUE when the passed cvolume structure is valid, FALSE otherwise */
128 int pa_cvolume_valid ( const pa_cvolume
* v
);
130 /** Return non-zero if the volume of all channels is equal to the specified value */
131 int pa_cvolume_channels_equal_to ( const pa_cvolume
* a
, pa_volume_t v
);
133 /** Return 1 if the specified volume has all channels muted */
134 #define pa_cvolume_is_muted(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_MUTED)
136 /** Return 1 if the specified volume has all channels on normal level */
137 #define pa_cvolume_is_norm(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_NORM)
139 /** Multiply two volumes specifications, return the result. This uses PA_VOLUME_NORM as neutral element of multiplication. This is only valid for software volumes! */
140 pa_volume_t
pa_sw_volume_multiply ( pa_volume_t a
, pa_volume_t b
);
142 /** Multiply to per-channel volumes and return the result in *dest. This is only valid for software volumes! */
143 pa_cvolume
* pa_sw_cvolume_multiply ( pa_cvolume
* dest
, const pa_cvolume
* a
, const pa_cvolume
* b
);
145 /** Convert a decibel value to a volume. This is only valid for software volumes! \since 0.4 */
146 pa_volume_t
pa_sw_volume_from_dB ( double f
);
148 /** Convert a volume to a decibel value. This is only valid for software volumes! \since 0.4 */
149 double pa_sw_volume_to_dB ( pa_volume_t v
);
151 /** Convert a linear factor to a volume. This is only valid for software volumes! \since 0.8 */
152 pa_volume_t
pa_sw_volume_from_linear ( double v
);
154 /** Convert a volume to a linear factor. This is only valid for software volumes! \since 0.8 */
155 double pa_sw_volume_to_linear ( pa_volume_t v
);
158 #define PA_DECIBEL_MININFTY (-INFINITY)
160 /** This value is used as minus infinity when using pa_volume_{to,from}_dB(). \since 0.4 */
161 #define PA_DECIBEL_MININFTY (-200)