| #ifndef foovolumehfoo | |
| #define foovolumehfoo | |
| /*** | |
| This file is part of PulseAudio. | |
| Copyright 2004-2006 Lennart Poettering | |
| Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB | |
| 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 2.1 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, see <http://www.gnu.org/licenses/>. | |
| ***/ | |
| #include <inttypes.h> | |
| #include <limits.h> | |
| #include <pulse/cdecl.h> | |
| #include <pulse/gccmacro.h> | |
| #include <pulse/sample.h> | |
| #include <pulse/channelmap.h> | |
| #include <pulse/version.h> | |
| /** \page volume Volume Control | |
| * | |
| * \section overv_sec Overview | |
| * | |
| * Sinks, sources, sink inputs, source outputs and samples can all have their | |
| * own volumes. To deal with these, The PulseAudio library contains a number of | |
| * functions that ease handling. | |
| * | |
| * The basic volume type in PulseAudio 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. | |
| * | |
| * There is no single well-defined meaning attached to the 100% volume for a | |
| * sink input. In fact, it depends on the server configuration. With flat | |
| * volumes enabled, it means the maximum volume that the sound hardware is | |
| * capable of, which is usually so high that you absolutely must not set sink | |
| * input volume to 100% unless the user explicitly requests that (note that | |
| * usually you shouldn't set the volume anyway if the user doesn't explicitly | |
| * request it, instead, let PulseAudio decide the volume for the sink input). | |
| * With flat volumes disabled the sink input volume is relative to the sink | |
| * volume, so 100% sink input volume means that the sink input is played at the | |
| * current sink volume level. In this case 100% is often a good default volume | |
| * for a sink input, although you still should let PulseAudio decide the | |
| * default volume. It is possible to figure out whether flat volume mode is in | |
| * effect for a given sink by calling pa_context_get_sink_info_by_name(). | |
| * | |
| * \section calc_sec Calculations | |
| * | |
| * The volumes in PulseAudio are cubic 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. | |
| * | |
| * It's often unknown what scale hardware volumes relate to. Don't use the | |
| * above functions on sink and source volumes, unless the sink or source in | |
| * question has the PA_SINK_DECIBEL_VOLUME or PA_SOURCE_DECIBEL_VOLUME flag | |
| * set. The conversion functions are rarely needed anyway, most of the time | |
| * it's sufficient to treat all volumes as opaque with a range from | |
| * PA_VOLUME_MUTED (0%) to PA_VOLUME_NORM (100%). | |
| * | |
| * \section conv_sec Convenience Functions | |
| * | |
| * To handle the pa_cvolume structure, the PulseAudio library provides a | |
| * number of convenience 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 the first n channels of a pa_cvolume structure to | |
| * a certain volume. | |
| * \li pa_cvolume_reset() - Set the first n channels of a pa_cvolume structure | |
| * to a normal volume. | |
| * \li pa_cvolume_mute() - Set the first n 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 | |
| * | |
| * See also \subpage volume | |
| */ | |
| 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%, 0 dB) */ | |
| #define PA_VOLUME_NORM ((pa_volume_t) 0x10000U) | |
| /** Muted (minimal valid) volume (0%, -inf dB) */ | |
| #define PA_VOLUME_MUTED ((pa_volume_t) 0U) | |
| /** Maximum valid volume we can store. \since 0.9.15 */ | |
| #define PA_VOLUME_MAX ((pa_volume_t) UINT32_MAX/2) | |
| /** Recommended maximum volume to show in user facing UIs. | |
| * Note: UIs should deal gracefully with volumes greater than this value | |
| * and not cause feedback loops etc. - i.e. if the volume is more than | |
| * this, the UI should not limit it and push the limited value back to | |
| * the server. \since 0.9.23 */ | |
| #define PA_VOLUME_UI_MAX (pa_sw_volume_from_dB(+11.0)) | |
| /** Special 'invalid' volume. \since 0.9.16 */ | |
| #define PA_VOLUME_INVALID ((pa_volume_t) UINT32_MAX) | |
| /** Check if volume is valid. \since 1.0 */ | |
| #define PA_VOLUME_IS_VALID(v) ((v) <= PA_VOLUME_MAX) | |
| /** Clamp volume to the permitted range. \since 1.0 */ | |
| #define PA_CLAMP_VOLUME(v) (PA_CLAMP_UNLIKELY((v), PA_VOLUME_MUTED, PA_VOLUME_MAX)) | |
| /** 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, checking that both a and b | |
| * have the same number of channels and that the volumes of | |
| * channels in a equal those in b. */ | |
| int pa_cvolume_equal(const pa_cvolume *a, const pa_cvolume *b) PA_GCC_PURE; | |
| /** Initialize the specified volume and return a pointer to | |
| * it. The sample spec will have a defined state but | |
| * pa_cvolume_valid() will fail for it. \since 0.9.13 */ | |
| pa_cvolume* pa_cvolume_init(pa_cvolume *a); | |
| /** Set the volume of the first n channels to PA_VOLUME_NORM */ | |
| #define pa_cvolume_reset(a, n) pa_cvolume_set((a), (n), PA_VOLUME_NORM) | |
| /** Set the volume of the first n channels to PA_VOLUME_MUTED */ | |
| #define pa_cvolume_mute(a, n) pa_cvolume_set((a), (n), PA_VOLUME_MUTED) | |
| /** Set the volume of the specified number of channels to the volume v */ | |
| pa_cvolume* pa_cvolume_set(pa_cvolume *a, unsigned channels, pa_volume_t v); | |
| /** Maximum length of the strings returned by | |
| * pa_cvolume_snprint(). Please note that this value can change with | |
| * any release without warning and without being considered API or ABI | |
| * breakage. You should not use this definition anywhere where it | |
| * might become part of an ABI.*/ | |
| #define PA_CVOLUME_SNPRINT_MAX 320 | |
| /** Pretty print a volume structure. Returns \a s. */ | |
| char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c); | |
| /** Maximum length of the strings returned by | |
| * pa_sw_cvolume_snprint_dB(). Please note that this value can change with | |
| * any release without warning and without being considered API or ABI | |
| * breakage. You should not use this definition anywhere where it | |
| * might become part of an ABI. \since 0.9.13 */ | |
| #define PA_SW_CVOLUME_SNPRINT_DB_MAX 448 | |
| /** Pretty print a volume structure, showing dB values. Returns \a s. \since 0.9.13 */ | |
| char *pa_sw_cvolume_snprint_dB(char *s, size_t l, const pa_cvolume *c); | |
| /** Maximum length of the strings returned by pa_cvolume_snprint_verbose(). | |
| * Please note that this value can change with any release without warning and | |
| * without being considered API or ABI breakage. You should not use this | |
| * definition anywhere where it might become part of an ABI. \since 5.0 */ | |
| #define PA_CVOLUME_SNPRINT_VERBOSE_MAX 1984 | |
| /** Pretty print a volume structure in a verbose way. The volume for each | |
| * channel is printed in several formats: the raw pa_volume_t value, | |
| * percentage, and if print_dB is non-zero, also the dB value. If map is not | |
| * NULL, the channel names will be printed. Returns \a s. \since 5.0 */ | |
| char *pa_cvolume_snprint_verbose(char *s, size_t l, const pa_cvolume *c, const pa_channel_map *map, int print_dB); | |
| /** Maximum length of the strings returned by | |
| * pa_volume_snprint(). Please note that this value can change with | |
| * any release without warning and without being considered API or ABI | |
| * breakage. You should not use this definition anywhere where it | |
| * might become part of an ABI. \since 0.9.15 */ | |
| #define PA_VOLUME_SNPRINT_MAX 10 | |
| /** Pretty print a volume. Returns \a s. \since 0.9.15 */ | |
| char *pa_volume_snprint(char *s, size_t l, pa_volume_t v); | |
| /** Maximum length of the strings returned by | |
| * pa_sw_volume_snprint_dB(). Please note that this value can change with | |
| * any release without warning and without being considered API or ABI | |
| * breakage. You should not use this definition anywhere where it | |
| * might become part of an ABI. \since 0.9.15 */ | |
| #define PA_SW_VOLUME_SNPRINT_DB_MAX 11 | |
| /** Pretty print a volume but show dB values. Returns \a s. \since 0.9.15 */ | |
| char *pa_sw_volume_snprint_dB(char *s, size_t l, pa_volume_t v); | |
| /** Maximum length of the strings returned by pa_volume_snprint_verbose(). | |
| * Please note that this value can change with any release without warning and | |
| * withou being considered API or ABI breakage. You should not use this | |
| * definition anywhere where it might become part of an ABI. \since 5.0 */ | |
| #define PA_VOLUME_SNPRINT_VERBOSE_MAX 35 | |
| /** Pretty print a volume in a verbose way. The volume is printed in several | |
| * formats: the raw pa_volume_t value, percentage, and if print_dB is non-zero, | |
| * also the dB value. Returns \a s. \since 5.0 */ | |
| char *pa_volume_snprint_verbose(char *s, size_t l, pa_volume_t v, int print_dB); | |
| /** Return the average volume of all channels */ | |
| pa_volume_t pa_cvolume_avg(const pa_cvolume *a) PA_GCC_PURE; | |
| /** Return the average volume of all channels that are included in the | |
| * specified channel map with the specified channel position mask. If | |
| * cm is NULL this call is identical to pa_cvolume_avg(). If no | |
| * channel is selected the returned value will be | |
| * PA_VOLUME_MUTED. \since 0.9.16 */ | |
| pa_volume_t pa_cvolume_avg_mask(const pa_cvolume *a, const pa_channel_map *cm, pa_channel_position_mask_t mask) PA_GCC_PURE; | |
| /** Return the maximum volume of all channels. \since 0.9.12 */ | |
| pa_volume_t pa_cvolume_max(const pa_cvolume *a) PA_GCC_PURE; | |
| /** Return the maximum volume of all channels that are included in the | |
| * specified channel map with the specified channel position mask. If | |
| * cm is NULL this call is identical to pa_cvolume_max(). If no | |
| * channel is selected the returned value will be PA_VOLUME_MUTED. | |
| * \since 0.9.16 */ | |
| pa_volume_t pa_cvolume_max_mask(const pa_cvolume *a, const pa_channel_map *cm, pa_channel_position_mask_t mask) PA_GCC_PURE; | |
| /** Return the minimum volume of all channels. \since 0.9.16 */ | |
| pa_volume_t pa_cvolume_min(const pa_cvolume *a) PA_GCC_PURE; | |
| /** Return the minimum volume of all channels that are included in the | |
| * specified channel map with the specified channel position mask. If | |
| * cm is NULL this call is identical to pa_cvolume_min(). If no | |
| * channel is selected the returned value will be PA_VOLUME_MUTED. | |
| * \since 0.9.16 */ | |
| pa_volume_t pa_cvolume_min_mask(const pa_cvolume *a, const pa_channel_map *cm, pa_channel_position_mask_t mask) PA_GCC_PURE; | |
| /** Return non-zero when the passed cvolume structure is valid */ | |
| int pa_cvolume_valid(const pa_cvolume *v) PA_GCC_PURE; | |
| /** 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) PA_GCC_PURE; | |
| /** 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 volume 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) PA_GCC_CONST; | |
| /** Multiply two per-channel volumes and return the result in | |
| * *dest. This is only valid for software volumes! a, b and dest may | |
| * point to the same structure. Returns dest, or NULL on error. */ | |
| pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b); | |
| /** Multiply a per-channel volume with a scalar volume and return the | |
| * result in *dest. This is only valid for software volumes! a | |
| * and dest may point to the same structure. Returns dest, or NULL on error. | |
| * \since 0.9.16 */ | |
| pa_cvolume *pa_sw_cvolume_multiply_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b); | |
| /** Divide two volume specifications, return the result. This uses | |
| * PA_VOLUME_NORM as neutral element of division. This is only valid | |
| * for software volumes! If a division by zero is tried the result | |
| * will be 0. \since 0.9.13 */ | |
| pa_volume_t pa_sw_volume_divide(pa_volume_t a, pa_volume_t b) PA_GCC_CONST; | |
| /** Divide two per-channel volumes and return the result in | |
| * *dest. This is only valid for software volumes! a, b | |
| * and dest may point to the same structure. Returns dest, | |
| * or NULL on error. \since 0.9.13 */ | |
| pa_cvolume *pa_sw_cvolume_divide(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b); | |
| /** Divide a per-channel volume by a scalar volume and return the | |
| * result in *dest. This is only valid for software volumes! a | |
| * and dest may point to the same structure. Returns dest, | |
| * or NULL on error. \since 0.9.16 */ | |
| pa_cvolume *pa_sw_cvolume_divide_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b); | |
| /** Convert a decibel value to a volume (amplitude, not power). This is only valid for software volumes! */ | |
| pa_volume_t pa_sw_volume_from_dB(double f) PA_GCC_CONST; | |
| /** Convert a volume to a decibel value (amplitude, not power). This is only valid for software volumes! */ | |
| double pa_sw_volume_to_dB(pa_volume_t v) PA_GCC_CONST; | |
| /** Convert a linear factor to a volume. 0.0 and less is muted while | |
| * 1.0 is PA_VOLUME_NORM. This is only valid for software volumes! */ | |
| pa_volume_t pa_sw_volume_from_linear(double v) PA_GCC_CONST; | |
| /** Convert a volume to a linear factor. This is only valid for software volumes! */ | |
| double pa_sw_volume_to_linear(pa_volume_t v) PA_GCC_CONST; | |
| #ifdef INFINITY | |
| #define PA_DECIBEL_MININFTY ((double) -INFINITY) | |
| #else | |
| /** This floor value is used as minus infinity when using pa_sw_volume_to_dB() / pa_sw_volume_from_dB(). */ | |
| #define PA_DECIBEL_MININFTY ((double) -200.0) | |
| #endif | |
| /** Remap a volume from one channel mapping to a different channel mapping. | |
| * Returns \a v. \since 0.9.12 */ | |
| pa_cvolume *pa_cvolume_remap(pa_cvolume *v, const pa_channel_map *from, const pa_channel_map *to); | |
| /** Return non-zero if the specified volume is compatible with the | |
| * specified sample spec. \since 0.9.13 */ | |
| int pa_cvolume_compatible(const pa_cvolume *v, const pa_sample_spec *ss) PA_GCC_PURE; | |
| /** Return non-zero if the specified volume is compatible with the | |
| * specified sample spec. \since 0.9.15 */ | |
| int pa_cvolume_compatible_with_channel_map(const pa_cvolume *v, const pa_channel_map *cm) PA_GCC_PURE; | |
| /** Calculate a 'balance' value for the specified volume with the | |
| * specified channel map. The return value will range from -1.0f | |
| * (left) to +1.0f (right). If no balance value is applicable to this | |
| * channel map the return value will always be 0.0f. See | |
| * pa_channel_map_can_balance(). \since 0.9.15 */ | |
| float pa_cvolume_get_balance(const pa_cvolume *v, const pa_channel_map *map) PA_GCC_PURE; | |
| /** Adjust the 'balance' value for the specified volume with the | |
| * specified channel map. v will be modified in place and | |
| * returned. The balance is a value between -1.0f and +1.0f. This | |
| * operation might not be reversible! Also, after this call | |
| * pa_cvolume_get_balance() is not guaranteed to actually return the | |
| * requested balance value (e.g. when the input volume was zero anyway for | |
| * all channels). If no balance value is applicable to | |
| * this channel map the volume will not be modified. See | |
| * pa_channel_map_can_balance(). Will return NULL on error. \since 0.9.15 */ | |
| pa_cvolume* pa_cvolume_set_balance(pa_cvolume *v, const pa_channel_map *map, float new_balance); | |
| /** Calculate a 'fade' value (i.e.\ 'balance' between front and rear) | |
| * for the specified volume with the specified channel map. The return | |
| * value will range from -1.0f (rear) to +1.0f (left). If no fade | |
| * value is applicable to this channel map the return value will | |
| * always be 0.0f. See pa_channel_map_can_fade(). \since 0.9.15 */ | |
| float pa_cvolume_get_fade(const pa_cvolume *v, const pa_channel_map *map) PA_GCC_PURE; | |
| /** Adjust the 'fade' value (i.e.\ 'balance' between front and rear) | |
| * for the specified volume with the specified channel map. v will be | |
| * modified in place and returned. The balance is a value between | |
| * -1.0f and +1.0f. This operation might not be reversible! Also, | |
| * after this call pa_cvolume_get_fade() is not guaranteed to actually | |
| * return the requested fade value (e.g. when the input volume was | |
| * zero anyway for all channels). If no fade value is applicable to | |
| * this channel map the volume will not be modified. See | |
| * pa_channel_map_can_fade(). Will return NULL on error. \since 0.9.15 */ | |
| pa_cvolume* pa_cvolume_set_fade(pa_cvolume *v, const pa_channel_map *map, float new_fade); | |
| /** Calculate a 'lfe balance' value for the specified volume with | |
| * the specified channel map. The return value will range from | |
| * -1.0f (no lfe) to +1.0f (only lfe), where 0.0f is balanced. | |
| * If no value is applicable to this channel map the return value | |
| * will always be 0.0f. See pa_channel_map_can_lfe_balance(). \since 8.0 */ | |
| float pa_cvolume_get_lfe_balance(const pa_cvolume *v, const pa_channel_map *map) PA_GCC_PURE; | |
| /** Adjust the 'lfe balance' value for the specified volume with | |
| * the specified channel map. v will be modified in place and returned. | |
| * The balance is a value between -1.0f (no lfe) and +1.0f (only lfe). | |
| * This operation might not be reversible! Also, after this call | |
| * pa_cvolume_get_lfe_balance() is not guaranteed to actually | |
| * return the requested value (e.g. when the input volume was | |
| * zero anyway for all channels). If no lfe balance value is applicable to | |
| * this channel map the volume will not be modified. See | |
| * pa_channel_map_can_lfe_balance(). Will return NULL on error. \since 8.0 */ | |
| pa_cvolume* pa_cvolume_set_lfe_balance(pa_cvolume *v, const pa_channel_map *map, float new_balance); | |
| /** Scale the passed pa_cvolume structure so that the maximum volume | |
| * of all channels equals max. The proportions between the channel | |
| * volumes are kept. Returns \a v, or NULL on error. \since 0.9.15 */ | |
| pa_cvolume* pa_cvolume_scale(pa_cvolume *v, pa_volume_t max); | |
| /** Scale the passed pa_cvolume structure so that the maximum volume | |
| * of all channels selected via cm/mask equals max. This also modifies | |
| * the volume of those channels that are unmasked. The proportions | |
| * between the channel volumes are kept. If cm is NULL this call is | |
| * identical to pa_cvolume_scale(). Returns \a v, or NULL on error. | |
| * \since 0.9.16 */ | |
| pa_cvolume* pa_cvolume_scale_mask(pa_cvolume *v, pa_volume_t max, const pa_channel_map *cm, pa_channel_position_mask_t mask); | |
| /** Set the passed volume to all channels at the specified channel | |
| * position. Will return the updated volume struct, or NULL if there | |
| * is no channel at the position specified. You can check if a channel | |
| * map includes a specific position by calling | |
| * pa_channel_map_has_position(). Returns \a cv, or NULL on error. | |
| * \since 0.9.16 */ | |
| pa_cvolume* pa_cvolume_set_position(pa_cvolume *cv, const pa_channel_map *map, pa_channel_position_t t, pa_volume_t v); | |
| /** Get the maximum volume of all channels at the specified channel | |
| * position. Will return 0 if there is no channel at the position | |
| * specified. You can check if a channel map includes a specific | |
| * position by calling pa_channel_map_has_position(). \since 0.9.16 */ | |
| pa_volume_t pa_cvolume_get_position(const pa_cvolume *cv, const pa_channel_map *map, pa_channel_position_t t) PA_GCC_PURE; | |
| /** This goes through all channels in a and b and sets the | |
| * corresponding channel in dest to the greater volume of both. a, b | |
| * and dest may point to the same structure. Returns \a dest, or NULL | |
| * on error. \since 0.9.16 */ | |
| pa_cvolume* pa_cvolume_merge(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b); | |
| /** Increase the volume passed in by 'inc', but not exceeding 'limit'. | |
| * The proportions between the channels are kept. | |
| * Returns \a v, or NULL on error. \since 0.9.19 */ | |
| pa_cvolume* pa_cvolume_inc_clamp(pa_cvolume *v, pa_volume_t inc, pa_volume_t limit); | |
| /** Increase the volume passed in by 'inc'. The proportions between | |
| * the channels are kept. Returns \a v, or NULL on error. \since 0.9.16 */ | |
| pa_cvolume* pa_cvolume_inc(pa_cvolume *v, pa_volume_t inc); | |
| /** Decrease the volume passed in by 'dec'. The proportions between | |
| * the channels are kept. Returns \a v, or NULL on error. \since 0.9.16 */ | |
| pa_cvolume* pa_cvolume_dec(pa_cvolume *v, pa_volume_t dec); | |
| PA_C_DECL_END | |
| #endif |