code.delx.au - pulseaudio/blob - src/pulse/channelmap.h

   1 #ifndef foochannelmaphfoo
   2 #define foochannelmaphfoo
   3
   4 /***
   5   This file is part of PulseAudio.
   6
   7   Copyright 2005-2006 Lennart Poettering
   8   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   9
  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.
  14
  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.
  19
  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
  23   USA.
  24 ***/
  25
  26 #include <pulse/sample.h>
  27 #include <pulse/cdecl.h>
  28 #include <pulse/gccmacro.h>
  29 #include <pulse/version.h>
  30
  31 /** \page channelmap Channel Maps
  32  *
  33  * \section overv_sec Overview
  34  *
  35  * Channel maps provide a way to associate channels in a stream with a
  36  * specific speaker position. This relieves applications of having to
  37  * make sure their channel order is identical to the final output.
  38  *
  39  * \section init_sec Initialisation
  40  *
  41  * A channel map consists of an array of \ref pa_channel_position values,
  42  * one for each channel. This array is stored together with a channel count
  43  * in a pa_channel_map structure.
  44  *
  45  * Before filling the structure, the application must initialise it using
  46  * pa_channel_map_init(). There are also a number of convenience functions
  47  * for standard channel mappings:
  48  *
  49  * \li pa_channel_map_init_mono() - Create a channel map with only mono audio.
  50  * \li pa_channel_map_init_stereo() - Create a standard stereo mapping.
  51  * \li pa_channel_map_init_auto() - Create a standard channel map for a specific number of channels
  52  * \li pa_channel_map_init_extend() - Similar to
  53  * pa_channel_map_init_auto() but synthesize a channel map if noone
  54  * predefined one is known for the specified number of channels.
  55  *
  56  * \section conv_sec Convenience Functions
  57  *
  58  * The library contains a number of convenience functions for dealing with
  59  * channel maps:
  60  *
  61  * \li pa_channel_map_valid() - Tests if a channel map is valid.
  62  * \li pa_channel_map_equal() - Tests if two channel maps are identical.
  63  * \li pa_channel_map_snprint() - Creates a textual description of a channel
  64  *                                map.
  65  */
  66
  67 /** \file
  68  * Constants and routines for channel mapping handling */
  69
  70 PA_C_DECL_BEGIN
  71
  72 /** A list of channel labels */
  73 typedef enum pa_channel_position {
  74     PA_CHANNEL_POSITION_INVALID = -1,
  75     PA_CHANNEL_POSITION_MONO = 0,
  76
  77     PA_CHANNEL_POSITION_LEFT,
  78     PA_CHANNEL_POSITION_RIGHT,
  79     PA_CHANNEL_POSITION_CENTER,
  80
  81     PA_CHANNEL_POSITION_FRONT_LEFT = PA_CHANNEL_POSITION_LEFT,
  82     PA_CHANNEL_POSITION_FRONT_RIGHT = PA_CHANNEL_POSITION_RIGHT,
  83     PA_CHANNEL_POSITION_FRONT_CENTER = PA_CHANNEL_POSITION_CENTER,
  84
  85     PA_CHANNEL_POSITION_REAR_CENTER,
  86     PA_CHANNEL_POSITION_REAR_LEFT,
  87     PA_CHANNEL_POSITION_REAR_RIGHT,
  88
  89     PA_CHANNEL_POSITION_LFE,
  90     PA_CHANNEL_POSITION_SUBWOOFER = PA_CHANNEL_POSITION_LFE,
  91
  92     PA_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER,
  93     PA_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER,
  94
  95     PA_CHANNEL_POSITION_SIDE_LEFT,
  96     PA_CHANNEL_POSITION_SIDE_RIGHT,
  97
  98     PA_CHANNEL_POSITION_AUX0,
  99     PA_CHANNEL_POSITION_AUX1,
 100     PA_CHANNEL_POSITION_AUX2,
 101     PA_CHANNEL_POSITION_AUX3,
 102     PA_CHANNEL_POSITION_AUX4,
 103     PA_CHANNEL_POSITION_AUX5,
 104     PA_CHANNEL_POSITION_AUX6,
 105     PA_CHANNEL_POSITION_AUX7,
 106     PA_CHANNEL_POSITION_AUX8,
 107     PA_CHANNEL_POSITION_AUX9,
 108     PA_CHANNEL_POSITION_AUX10,
 109     PA_CHANNEL_POSITION_AUX11,
 110     PA_CHANNEL_POSITION_AUX12,
 111     PA_CHANNEL_POSITION_AUX13,
 112     PA_CHANNEL_POSITION_AUX14,
 113     PA_CHANNEL_POSITION_AUX15,
 114     PA_CHANNEL_POSITION_AUX16,
 115     PA_CHANNEL_POSITION_AUX17,
 116     PA_CHANNEL_POSITION_AUX18,
 117     PA_CHANNEL_POSITION_AUX19,
 118     PA_CHANNEL_POSITION_AUX20,
 119     PA_CHANNEL_POSITION_AUX21,
 120     PA_CHANNEL_POSITION_AUX22,
 121     PA_CHANNEL_POSITION_AUX23,
 122     PA_CHANNEL_POSITION_AUX24,
 123     PA_CHANNEL_POSITION_AUX25,
 124     PA_CHANNEL_POSITION_AUX26,
 125     PA_CHANNEL_POSITION_AUX27,
 126     PA_CHANNEL_POSITION_AUX28,
 127     PA_CHANNEL_POSITION_AUX29,
 128     PA_CHANNEL_POSITION_AUX30,
 129     PA_CHANNEL_POSITION_AUX31,
 130
 131     PA_CHANNEL_POSITION_TOP_CENTER,
 132
 133     PA_CHANNEL_POSITION_TOP_FRONT_LEFT,
 134     PA_CHANNEL_POSITION_TOP_FRONT_RIGHT,
 135     PA_CHANNEL_POSITION_TOP_FRONT_CENTER,
 136
 137     PA_CHANNEL_POSITION_TOP_REAR_LEFT,
 138     PA_CHANNEL_POSITION_TOP_REAR_RIGHT,
 139     PA_CHANNEL_POSITION_TOP_REAR_CENTER,
 140
 141     PA_CHANNEL_POSITION_MAX
 142 } pa_channel_position_t;
 143
 144 /** A list of channel mapping definitions for pa_channel_map_init_auto() */
 145 typedef enum pa_channel_map_def {
 146     PA_CHANNEL_MAP_AIFF,
 147     /**< The mapping from RFC3551, which is based on AIFF-C */
 148
 149     PA_CHANNEL_MAP_ALSA,
 150     /**< The default mapping used by ALSA */
 151
 152     PA_CHANNEL_MAP_AUX,
 153     /**< Only aux channels */
 154
 155     PA_CHANNEL_MAP_WAVEEX,
 156     /**< Microsoft's WAVEFORMATEXTENSIBLE mapping */
 157
 158     PA_CHANNEL_MAP_OSS,
 159     /**< The default channel mapping used by OSS as defined in the OSS 4.0 API specs */
 160
 161     /**< Upper limit of valid channel mapping definitions */
 162     PA_CHANNEL_MAP_DEF_MAX,
 163
 164     PA_CHANNEL_MAP_DEFAULT = PA_CHANNEL_MAP_AIFF
 165     /**< The default channel map */
 166 } pa_channel_map_def_t;
 167
 168 /** A channel map which can be used to attach labels to specific
 169  * channels of a stream. These values are relevant for conversion and
 170  * mixing of streams */
 171 typedef struct pa_channel_map {
 172     uint8_t channels;
 173     /**< Number of channels */
 174
 175     pa_channel_position_t map[PA_CHANNELS_MAX];
 176     /**< Channel labels */
 177 } pa_channel_map;
 178
 179 /** Initialize the specified channel map and return a pointer to
 180  * it. The channel map will have a defined state but
 181  * pa_channel_map_valid() will fail for it. */
 182 pa_channel_map* pa_channel_map_init(pa_channel_map *m);
 183
 184 /** Initialize the specified channel map for monoaural audio and return a pointer to it */
 185 pa_channel_map* pa_channel_map_init_mono(pa_channel_map *m);
 186
 187 /** Initialize the specified channel map for stereophonic audio and return a pointer to it */
 188 pa_channel_map* pa_channel_map_init_stereo(pa_channel_map *m);
 189
 190 /** Initialize the specified channel map for the specified number of
 191  * channels using default labels and return a pointer to it. This call
 192  * will fail (return NULL) if there is no default channel map known for this
 193  * specific number of channels and mapping. */
 194 pa_channel_map* pa_channel_map_init_auto(pa_channel_map *m, unsigned channels, pa_channel_map_def_t def);
 195
 196 /** Similar to pa_channel_map_init_auto() but instead of failing if no
 197  * default mapping is known with the specified parameters it will
 198  * synthesize a mapping based on a known mapping with fewer channels
 199  * and fill up the rest with AUX0...AUX31 channels  \since 0.9.11 */
 200 pa_channel_map* pa_channel_map_init_extend(pa_channel_map *m, unsigned channels, pa_channel_map_def_t def);
 201
 202 /** Return a text label for the specified channel position */
 203 const char* pa_channel_position_to_string(pa_channel_position_t pos) PA_GCC_PURE;
 204
 205 /** Return a human readable text label for the specified channel position. \since 0.9.7 */
 206 const char* pa_channel_position_to_pretty_string(pa_channel_position_t pos);
 207
 208 /** The maximum length of strings returned by
 209  * pa_channel_map_snprint(). Please note that this value can change
 210  * with any release without warning and without being considered API
 211  * or ABI breakage. You should not use this definition anywhere where
 212  * it might become part of an ABI. */
 213 #define PA_CHANNEL_MAP_SNPRINT_MAX 336
 214
 215 /** Make a humand readable string from the specified channel map */
 216 char* pa_channel_map_snprint(char *s, size_t l, const pa_channel_map *map);
 217
 218 /** Parse a channel position list or well-known mapping name into a
 219  * channel map structure. This turns the output of
 220  * pa_channel_map_snprint() and pa_channel_map_to_name() back into a
 221  * pa_channel_map */
 222 pa_channel_map *pa_channel_map_parse(pa_channel_map *map, const char *s);
 223
 224 /** Compare two channel maps. Return 1 if both match. */
 225 int pa_channel_map_equal(const pa_channel_map *a, const pa_channel_map *b) PA_GCC_PURE;
 226
 227 /** Return non-zero if the specified channel map is considered valid */
 228 int pa_channel_map_valid(const pa_channel_map *map) PA_GCC_PURE;
 229
 230 /** Return non-zero if the specified channel map is compatible with
 231  * the specified sample spec. \since 0.9.12 */
 232 int pa_channel_map_compatible(const pa_channel_map *map, const pa_sample_spec *ss) PA_GCC_PURE;
 233
 234 /** Returns non-zero if every channel defined in b is also defined in a. \since 0.9.15 */
 235 int pa_channel_map_superset(const pa_channel_map *a, const pa_channel_map *b) PA_GCC_PURE;
 236
 237 /** Returns non-zero if it makes sense to apply a volume 'balance'
 238  * with this mapping, i.e. if there are left/right channels
 239  * available. \since 0.9.15 */
 240 int pa_channel_map_can_balance(const pa_channel_map *map) PA_GCC_PURE;
 241
 242 /** Tries to find a well-known channel mapping name for this channel
 243  * mapping. I.e. "stereo", "surround-71" and so on. If the channel
 244  * mapping is unknown NULL will be returned. This name can be parsed
 245  * with pa_channel_map_parse() \since 0.9.15 */
 246 const char* pa_channel_map_to_name(const pa_channel_map *map) PA_GCC_PURE;
 247
 248 /** Tries to find a human readable text label for this channel
 249 mapping. I.e. "Stereo", "Surround 7.1" and so on. If the channel
 250 mapping is unknown NULL will be returned. \since 0.9.15 */
 251 const char* pa_channel_map_to_pretty_name(const pa_channel_map *map) PA_GCC_PURE;
 252
 253 PA_C_DECL_END
 254
 255 #endif