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Diffstat (limited to 'src/pulse/volume.h')
| -rw-r--r-- | src/pulse/volume.h | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/src/pulse/volume.h b/src/pulse/volume.h new file mode 100644 index 000000000..d403a09e3 --- /dev/null +++ b/src/pulse/volume.h @@ -0,0 +1,172 @@ +#ifndef foovolumehfoo +#define foovolumehfoo + +/* $Id$ */ + +/*** + This file is part of PulseAudio. + + PulseAudio is free software; you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as published + by the Free Software Foundation; either version 2 of the License, + or (at your option) any later version. + + PulseAudio is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with PulseAudio; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 + USA. +***/ + +#include <inttypes.h> +#include <pulse/cdecl.h> +#include <pulse/sample.h> + +/** \page volume Volume Control + * + * \section overv_sec Overview + * + * Sinks, sources, sink inputs and samples can all have their own volumes. + * To deal with these, The Polypaudio libray contains a number of functions + * that ease handling. + * + * The basic volume type in Polypaudio is the \ref pa_volume_t type. Most of + * the time, applications will use the aggregated pa_cvolume structure that + * can store the volume of all channels at once. + * + * Volumes commonly span between muted (0%), and normal (100%). It is possible + * to set volumes to higher than 100%, but clipping might occur. + * + * \section calc_sec Calculations + * + * The volumes in Polypaudio are logarithmic in nature and applications + * shouldn't perform calculations with them directly. Instead, they should + * be converted to and from either dB or a linear scale: + * + * \li dB - pa_sw_volume_from_dB() / pa_sw_volume_to_dB() + * \li Linear - pa_sw_volume_from_linear() / pa_sw_volume_to_linear() + * + * For simple multiplication, pa_sw_volume_multiply() and + * pa_sw_cvolume_multiply() can be used. + * + * Calculations can only be reliably performed on software volumes + * as it is commonly unknown what scale hardware volumes relate to. + * + * The functions described above are only valid when used with + * software volumes. Hence it is usually a better idea to treat all + * volume values as opaque with a range from PA_VOLUME_MUTE (0%) to + * PA_VOLUME_NORM (100%) and to refrain from any calculations with + * them. + * + * \section conv_sec Convenience Functions + * + * To handle the pa_cvolume structure, the Polypaudio library provides a + * number of convenienc functions: + * + * \li pa_cvolume_valid() - Tests if a pa_cvolume structure is valid. + * \li pa_cvolume_equal() - Tests if two pa_cvolume structures are identical. + * \li pa_cvolume_channels_equal_to() - Tests if all channels of a pa_cvolume + * structure have a given volume. + * \li pa_cvolume_is_muted() - Tests if all channels of a pa_cvolume + * structure are muted. + * \li pa_cvolume_is_norm() - Tests if all channels of a pa_cvolume structure + * are at a normal volume. + * \li pa_cvolume_set() - Set all channels of a pa_cvolume structure to a + * certain volume. + * \li pa_cvolume_reset() - Set all channels of a pa_cvolume structure to a + * normal volume. + * \li pa_cvolume_mute() - Set all channels of a pa_cvolume structure to a + * muted volume. + * \li pa_cvolume_avg() - Return the average volume of all channels. + * \li pa_cvolume_snprint() - Pretty print a pa_cvolume structure. + */ + +/** \file + * Constants and routines for volume handling */ + +PA_C_DECL_BEGIN + +/** Volume specification: + * PA_VOLUME_MUTED: silence; + * < PA_VOLUME_NORM: decreased volume; + * PA_VOLUME_NORM: normal volume; + * > PA_VOLUME_NORM: increased volume */ +typedef uint32_t pa_volume_t; + +/** Normal volume (100%) */ +#define PA_VOLUME_NORM (0x10000) + +/** Muted volume (0%) */ +#define PA_VOLUME_MUTED (0) + +/** A structure encapsulating a per-channel volume */ +typedef struct pa_cvolume { + uint8_t channels; /**< Number of channels */ + pa_volume_t values[PA_CHANNELS_MAX]; /**< Per-channel volume */ +} pa_cvolume; + +/** Return non-zero when *a == *b */ +int pa_cvolume_equal(const pa_cvolume *a, const pa_cvolume *b); + +/** Set the volume of all channels to PA_VOLUME_NORM */ +#define pa_cvolume_reset(a, n) pa_cvolume_set((a), (n), PA_VOLUME_NORM) + +/** Set the volume of all channels to PA_VOLUME_MUTED */ +#define pa_cvolume_mute(a, n) pa_cvolume_set((a), (n), PA_VOLUME_MUTED) + +/** Set the volume of all channels to the specified parameter */ +pa_cvolume* pa_cvolume_set(pa_cvolume *a, unsigned channels, pa_volume_t v); + +/** Maximum length of the strings returned by pa_cvolume_snprint() */ +#define PA_CVOLUME_SNPRINT_MAX 64 + +/** Pretty print a volume structure */ +char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c); + +/** Return the average volume of all channels */ +pa_volume_t pa_cvolume_avg(const pa_cvolume *a); + +/** Return TRUE when the passed cvolume structure is valid, FALSE otherwise */ +int pa_cvolume_valid(const pa_cvolume *v); + +/** Return non-zero if the volume of all channels is equal to the specified value */ +int pa_cvolume_channels_equal_to(const pa_cvolume *a, pa_volume_t v); + +/** Return 1 if the specified volume has all channels muted */ +#define pa_cvolume_is_muted(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_MUTED) + +/** Return 1 if the specified volume has all channels on normal level */ +#define pa_cvolume_is_norm(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_NORM) + +/** Multiply two volumes specifications, return the result. This uses PA_VOLUME_NORM as neutral element of multiplication. This is only valid for software volumes! */ +pa_volume_t pa_sw_volume_multiply(pa_volume_t a, pa_volume_t b); + +/** Multiply to per-channel volumes and return the result in *dest. This is only valid for software volumes! */ +pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b); + +/** Convert a decibel value to a volume. This is only valid for software volumes! \since 0.4 */ +pa_volume_t pa_sw_volume_from_dB(double f); + +/** Convert a volume to a decibel value. This is only valid for software volumes! \since 0.4 */ +double pa_sw_volume_to_dB(pa_volume_t v); + +/** Convert a linear factor to a volume. This is only valid for software volumes! \since 0.8 */ +pa_volume_t pa_sw_volume_from_linear(double v); + +/** Convert a volume to a linear factor. This is only valid for software volumes! \since 0.8 */ +double pa_sw_volume_to_linear(pa_volume_t v); + +#ifdef INFINITY +#define PA_DECIBEL_MININFTY (-INFINITY) +#else +/** This value is used as minus infinity when using pa_volume_{to,from}_dB(). \since 0.4 */ +#define PA_DECIBEL_MININFTY (-200) +#endif + +PA_C_DECL_END + +#endif |