PulseAudio 16.1

Data Structures | Macros | Typedefs | Enumerations | Functions
channelmap.h File Reference

Constants and routines for channel mapping handling. More...

Go to the source code of this file.

## Data Structures
struct | pa_channel_map
| A channel map which can be used to attach labels to specific channels of a stream. More...

## Macros
#define | PA_CHANNEL_POSITION_MASK(f) ((pa_channel_position_mask_t) (1ULL << (f)))
| Makes a bit mask from a channel position. More...
#define | PA_CHANNEL_MAP_SNPRINT_MAX 336
| The maximum length of strings returned by pa_channel_map_snprint(). More...

## Typedefs
typedef enum pa_channel_position | pa_channel_position_t
| A list of channel labels. More...
typedef uint64_t | pa_channel_position_mask_t
| A mask of channel positions. More...
typedef enum pa_channel_map_def | pa_channel_map_def_t
| A list of channel mapping definitions for pa_channel_map_init_auto() More...
typedef struct pa_channel_map | pa_channel_map
| A channel map which can be used to attach labels to specific channels of a stream. More...

## Enumerations
enum | pa_channel_position { PA_CHANNEL_POSITION_INVALID = -1 , PA_CHANNEL_POSITION_MONO = 0 , PA_CHANNEL_POSITION_FRONT_LEFT , PA_CHANNEL_POSITION_FRONT_RIGHT , PA_CHANNEL_POSITION_FRONT_CENTER , PA_CHANNEL_POSITION_REAR_CENTER , PA_CHANNEL_POSITION_REAR_LEFT , PA_CHANNEL_POSITION_REAR_RIGHT , PA_CHANNEL_POSITION_LFE , PA_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER , PA_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER , PA_CHANNEL_POSITION_SIDE_LEFT , PA_CHANNEL_POSITION_SIDE_RIGHT , PA_CHANNEL_POSITION_AUX0 , PA_CHANNEL_POSITION_AUX1 , PA_CHANNEL_POSITION_AUX2 , PA_CHANNEL_POSITION_AUX3 , PA_CHANNEL_POSITION_AUX4 , PA_CHANNEL_POSITION_AUX5 , PA_CHANNEL_POSITION_AUX6 , PA_CHANNEL_POSITION_AUX7 , PA_CHANNEL_POSITION_AUX8 , PA_CHANNEL_POSITION_AUX9 , PA_CHANNEL_POSITION_AUX10 , PA_CHANNEL_POSITION_AUX11 , PA_CHANNEL_POSITION_AUX12 , PA_CHANNEL_POSITION_AUX13 , PA_CHANNEL_POSITION_AUX14 , PA_CHANNEL_POSITION_AUX15 , PA_CHANNEL_POSITION_AUX16 , PA_CHANNEL_POSITION_AUX17 , PA_CHANNEL_POSITION_AUX18 , PA_CHANNEL_POSITION_AUX19 , PA_CHANNEL_POSITION_AUX20 , PA_CHANNEL_POSITION_AUX21 , PA_CHANNEL_POSITION_AUX22 , PA_CHANNEL_POSITION_AUX23 , PA_CHANNEL_POSITION_AUX24 , PA_CHANNEL_POSITION_AUX25 , PA_CHANNEL_POSITION_AUX26 , PA_CHANNEL_POSITION_AUX27 , PA_CHANNEL_POSITION_AUX28 , PA_CHANNEL_POSITION_AUX29 , PA_CHANNEL_POSITION_AUX30 , PA_CHANNEL_POSITION_AUX31 , PA_CHANNEL_POSITION_TOP_CENTER , PA_CHANNEL_POSITION_TOP_FRONT_LEFT , PA_CHANNEL_POSITION_TOP_FRONT_RIGHT , PA_CHANNEL_POSITION_TOP_FRONT_CENTER , PA_CHANNEL_POSITION_TOP_REAR_LEFT , PA_CHANNEL_POSITION_TOP_REAR_RIGHT , PA_CHANNEL_POSITION_TOP_REAR_CENTER , PA_CHANNEL_POSITION_MAX }
| A list of channel labels. More...
enum | pa_channel_map_def { PA_CHANNEL_MAP_AIFF , PA_CHANNEL_MAP_AUX , PA_CHANNEL_MAP_WAVEEX , PA_CHANNEL_MAP_DEF_MAX , PA_CHANNEL_MAP_DEFAULT = PA_CHANNEL_MAP_AIFF }
| A list of channel mapping definitions for pa_channel_map_init_auto() More...

## Functions
pa_channel_map * | pa_channel_map_init (pa_channel_map *m)
| Initialize the specified channel map and return a pointer to it. More...
pa_channel_map * | pa_channel_map_init_mono (pa_channel_map *m)
| Initialize the specified channel map for monaural audio and return a pointer to it. More...
pa_channel_map * | pa_channel_map_init_stereo (pa_channel_map *m)
| Initialize the specified channel map for stereophonic audio and return a pointer to it. More...
pa_channel_map * | pa_channel_map_init_auto (pa_channel_map *m, unsigned channels, pa_channel_map_def_t def)
| Initialize the specified channel map for the specified number of channels using default labels and return a pointer to it. More...
pa_channel_map * | pa_channel_map_init_extend (pa_channel_map *m, unsigned channels, pa_channel_map_def_t def)
| Similar to pa_channel_map_init_auto() but instead of failing if no default mapping is known with the specified parameters it will synthesize a mapping based on a known mapping with fewer channels and fill up the rest with AUX0...AUX31 channels. More...
const char * | pa_channel_position_to_string (pa_channel_position_t pos) PA_GCC_PURE
| Return a text label for the specified channel position. More...
pa_channel_position_t | pa_channel_position_from_string (const char *s) PA_GCC_PURE
| The inverse of pa_channel_position_to_string(). More...
const char * | pa_channel_position_to_pretty_string (pa_channel_position_t pos)
| Return a human readable text label for the specified channel position. More...
char * | pa_channel_map_snprint (char *s, size_t l, const pa_channel_map *map)
| Make a human readable string from the specified channel map. More...
pa_channel_map * | pa_channel_map_parse (pa_channel_map *map, const char *s)
| Parse a channel position list or well-known mapping name into a channel map structure. More...
int | pa_channel_map_equal (const pa_channel_map *a, const pa_channel_map *b) PA_GCC_PURE
| Compare two channel maps. More...
int | pa_channel_map_valid (const pa_channel_map *map) PA_GCC_PURE
| Return non-zero if the specified channel map is considered valid. More...
int | pa_channel_map_compatible (const pa_channel_map *map, const pa_sample_spec *ss) PA_GCC_PURE
| Return non-zero if the specified channel map is compatible with the specified sample spec. More...
int | pa_channel_map_superset (const pa_channel_map *a, const pa_channel_map *b) PA_GCC_PURE
| Returns non-zero if every channel defined in b is also defined in a. More...
int | pa_channel_map_can_balance (const pa_channel_map *map) PA_GCC_PURE
| Returns non-zero if it makes sense to apply a volume 'balance' with this mapping, i.e. if there are left/right channels available. More...
int | pa_channel_map_can_fade (const pa_channel_map *map) PA_GCC_PURE
| Returns non-zero if it makes sense to apply a volume 'fade' (i.e. 'balance' between front and rear) with this mapping, i.e. if there are front/rear channels available. More...
int | pa_channel_map_can_lfe_balance (const pa_channel_map *map) PA_GCC_PURE
| Returns non-zero if it makes sense to apply a volume 'lfe balance' (i.e. 'balance' between LFE and non-LFE channels) with this mapping, i.e. if there are LFE and non-LFE channels available. More...
const char * | pa_channel_map_to_name (const pa_channel_map *map) PA_GCC_PURE
| Tries to find a well-known channel mapping name for this channel mapping, i.e. "stereo", "surround-71" and so on. More...
const char * | pa_channel_map_to_pretty_name (const pa_channel_map *map) PA_GCC_PURE
| Tries to find a human readable text label for this channel mapping, i.e. "Stereo", "Surround 7.1" and so on. More...
int | pa_channel_map_has_position (const pa_channel_map *map, pa_channel_position_t p) PA_GCC_PURE
| Returns non-zero if the specified channel position is available at least once in the channel map. More...
pa_channel_position_mask_t | pa_channel_map_mask (const pa_channel_map *map) PA_GCC_PURE
| Generates a bit mask from a channel map. More...

## Detailed Description

Constants and routines for channel mapping handling.

See also Channel Maps

## Macro Definition Documentation

## ◆ PA_CHANNEL_MAP_SNPRINT_MAX

#define PA_CHANNEL_MAP_SNPRINT_MAX 336

The maximum length of strings returned by pa_channel_map_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.

## ◆ PA_CHANNEL_POSITION_MASK

#define PA_CHANNEL_POSITION_MASK | ( |  | f | ) | ((pa_channel_position_mask_t) (1ULL << (f)))

Makes a bit mask from a channel position.

Since
  0.9.16

## Typedef Documentation

## ◆ pa_channel_map

typedef struct pa_channel_map pa_channel_map

A channel map which can be used to attach labels to specific channels of a stream.

These values are relevant for conversion and mixing of streams

## ◆ pa_channel_map_def_t

typedef enum pa_channel_map_def pa_channel_map_def_t

A list of channel mapping definitions for pa_channel_map_init_auto()

## ◆ pa_channel_position_mask_t

typedef uint64_t pa_channel_position_mask_t

A mask of channel positions.

Since
  0.9.16

## ◆ pa_channel_position_t

typedef enum pa_channel_position pa_channel_position_t

A list of channel labels.

## Enumeration Type Documentation

## ◆ pa_channel_map_def

enum pa_channel_map_def

A list of channel mapping definitions for pa_channel_map_init_auto()

Enumerator
PA_CHANNEL_MAP_AIFF | The mapping from RFC3551, which is based on AIFF-C.
PA_CHANNEL_MAP_AUX | Only aux channels.
PA_CHANNEL_MAP_WAVEEX | Microsoft's WAVEFORMATEXTENSIBLE mapping. This mapping works as if all LSBs of dwChannelMask are set.
PA_CHANNEL_MAP_DEF_MAX | Upper limit of valid channel mapping definitions.
PA_CHANNEL_MAP_DEFAULT | The default channel map.

## ◆ pa_channel_position

enum pa_channel_position

A list of channel labels.

Enumerator
PA_CHANNEL_POSITION_INVALID |
PA_CHANNEL_POSITION_MONO |
PA_CHANNEL_POSITION_FRONT_LEFT | Apple, Dolby call this 'Left'.
PA_CHANNEL_POSITION_FRONT_RIGHT | Apple, Dolby call this 'Right'.
PA_CHANNEL_POSITION_FRONT_CENTER | Apple, Dolby call this 'Center'.
PA_CHANNEL_POSITION_REAR_CENTER | Microsoft calls this 'Back Center', Apple calls this 'Center Surround', Dolby calls this 'Surround Rear Center'.
PA_CHANNEL_POSITION_REAR_LEFT | Microsoft calls this 'Back Left', Apple calls this 'Left Surround' (!), Dolby calls this 'Surround Rear Left'
PA_CHANNEL_POSITION_REAR_RIGHT | Microsoft calls this 'Back Right', Apple calls this 'Right Surround' (!), Dolby calls this 'Surround Rear Right'
PA_CHANNEL_POSITION_LFE | Microsoft calls this 'Low Frequency', Apple calls this 'LFEScreen'.
PA_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER | Apple, Dolby call this 'Left Center'.
PA_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER | Apple, Dolby call this 'Right Center.
PA_CHANNEL_POSITION_SIDE_LEFT | Apple calls this 'Left Surround Direct', Dolby calls this 'Surround Left' (!)
PA_CHANNEL_POSITION_SIDE_RIGHT | Apple calls this 'Right Surround Direct', Dolby calls this 'Surround Right' (!)
PA_CHANNEL_POSITION_AUX0 |
PA_CHANNEL_POSITION_AUX1 |
PA_CHANNEL_POSITION_AUX2 |
PA_CHANNEL_POSITION_AUX3 |
PA_CHANNEL_POSITION_AUX4 |
PA_CHANNEL_POSITION_AUX5 |
PA_CHANNEL_POSITION_AUX6 |
PA_CHANNEL_POSITION_AUX7 |
PA_CHANNEL_POSITION_AUX8 |
PA_CHANNEL_POSITION_AUX9 |
PA_CHANNEL_POSITION_AUX10 |
PA_CHANNEL_POSITION_AUX11 |
PA_CHANNEL_POSITION_AUX12 |
PA_CHANNEL_POSITION_AUX13 |
PA_CHANNEL_POSITION_AUX14 |
PA_CHANNEL_POSITION_AUX15 |
PA_CHANNEL_POSITION_AUX16 |
PA_CHANNEL_POSITION_AUX17 |
PA_CHANNEL_POSITION_AUX18 |
PA_CHANNEL_POSITION_AUX19 |
PA_CHANNEL_POSITION_AUX20 |
PA_CHANNEL_POSITION_AUX21 |
PA_CHANNEL_POSITION_AUX22 |
PA_CHANNEL_POSITION_AUX23 |
PA_CHANNEL_POSITION_AUX24 |
PA_CHANNEL_POSITION_AUX25 |
PA_CHANNEL_POSITION_AUX26 |
PA_CHANNEL_POSITION_AUX27 |
PA_CHANNEL_POSITION_AUX28 |
PA_CHANNEL_POSITION_AUX29 |
PA_CHANNEL_POSITION_AUX30 |
PA_CHANNEL_POSITION_AUX31 |
PA_CHANNEL_POSITION_TOP_CENTER | Apple calls this 'Top Center Surround'.
PA_CHANNEL_POSITION_TOP_FRONT_LEFT | Apple calls this 'Vertical Height Left'.
PA_CHANNEL_POSITION_TOP_FRONT_RIGHT | Apple calls this 'Vertical Height Right'.
PA_CHANNEL_POSITION_TOP_FRONT_CENTER | Apple calls this 'Vertical Height Center'.
PA_CHANNEL_POSITION_TOP_REAR_LEFT | Microsoft and Apple call this 'Top Back Left'.
PA_CHANNEL_POSITION_TOP_REAR_RIGHT | Microsoft and Apple call this 'Top Back Right'.
PA_CHANNEL_POSITION_TOP_REAR_CENTER | Microsoft and Apple call this 'Top Back Center'.
PA_CHANNEL_POSITION_MAX |

## Function Documentation

## ◆ pa_channel_map_can_balance()

int pa_channel_map_can_balance | ( | const pa_channel_map * | map | ) |

Returns non-zero if it makes sense to apply a volume 'balance' with this mapping, i.e. if there are left/right channels available.

Since
  0.9.15

## ◆ pa_channel_map_can_fade()

int pa_channel_map_can_fade | ( | const pa_channel_map * | map | ) |

Returns non-zero if it makes sense to apply a volume 'fade' (i.e. 'balance' between front and rear) with this mapping, i.e. if there are front/rear channels available.

Since
  0.9.15

## ◆ pa_channel_map_can_lfe_balance()

int pa_channel_map_can_lfe_balance | ( | const pa_channel_map * | map | ) |

Returns non-zero if it makes sense to apply a volume 'lfe balance' (i.e. 'balance' between LFE and non-LFE channels) with this mapping, i.e. if there are LFE and non-LFE channels available.

Since
  8.0

## ◆ pa_channel_map_compatible()

int pa_channel_map_compatible | ( | const pa_channel_map * | map,
|  | const pa_sample_spec * | ss
| ) |  |

Return non-zero if the specified channel map is compatible with the specified sample spec.

Since
  0.9.12

## ◆ pa_channel_map_equal()

int pa_channel_map_equal | ( | const pa_channel_map * | a,
|  | const pa_channel_map * | b
| ) |  |

Compare two channel maps.

Return 1 if both match.

## ◆ pa_channel_map_has_position()

int pa_channel_map_has_position | ( | const pa_channel_map * | map,
|  | pa_channel_position_t | p
| ) |  |

Returns non-zero if the specified channel position is available at least once in the channel map.

Since
  0.9.16

## ◆ pa_channel_map_init()

pa_channel_map * pa_channel_map_init | ( | pa_channel_map * | m | ) |

Initialize the specified channel map and return a pointer to it.

The channel map will have a defined state but pa_channel_map_valid() will fail for it.

## ◆ pa_channel_map_init_auto()

pa_channel_map * pa_channel_map_init_auto | ( | pa_channel_map * | m,
|  | unsigned | channels,
|  | pa_channel_map_def_t | def
| ) |  |

Initialize the specified channel map for the specified number of channels using default labels and return a pointer to it.

This call will fail (return NULL) if there is no default channel map known for this specific number of channels and mapping.

## ◆ pa_channel_map_init_extend()

pa_channel_map * pa_channel_map_init_extend | ( | pa_channel_map * | m,
|  | unsigned | channels,
|  | pa_channel_map_def_t | def
| ) |  |

Similar to pa_channel_map_init_auto() but instead of failing if no default mapping is known with the specified parameters it will synthesize a mapping based on a known mapping with fewer channels and fill up the rest with AUX0...AUX31 channels.

Since
  0.9.11

## ◆ pa_channel_map_init_mono()

pa_channel_map * pa_channel_map_init_mono | ( | pa_channel_map * | m | ) |

Initialize the specified channel map for monaural audio and return a pointer to it.

## ◆ pa_channel_map_init_stereo()

pa_channel_map * pa_channel_map_init_stereo | ( | pa_channel_map * | m | ) |

Initialize the specified channel map for stereophonic audio and return a pointer to it.

## ◆ pa_channel_map_mask()

pa_channel_position_mask_t pa_channel_map_mask | ( | const pa_channel_map * | map | ) |

Generates a bit mask from a channel map.

Since
  0.9.16

## ◆ pa_channel_map_parse()

pa_channel_map * pa_channel_map_parse | ( | pa_channel_map * | map,
|  | const char * | s
| ) |  |

Parse a channel position list or well-known mapping name into a channel map structure.

This turns the output of pa_channel_map_snprint() and pa_channel_map_to_name() back into a pa_channel_map

## ◆ pa_channel_map_snprint()

char * pa_channel_map_snprint | ( | char * | s,
|  | size_t | l,
|  | const pa_channel_map * | map
| ) |  |

Make a human readable string from the specified channel map.

Returns s.

## ◆ pa_channel_map_superset()

int pa_channel_map_superset | ( | const pa_channel_map * | a,
|  | const pa_channel_map * | b
| ) |  |

Returns non-zero if every channel defined in b is also defined in a.

Since
  0.9.15

## ◆ pa_channel_map_to_name()

const char * pa_channel_map_to_name | ( | const pa_channel_map * | map | ) |

Tries to find a well-known channel mapping name for this channel mapping, i.e. "stereo", "surround-71" and so on.

If the channel mapping is unknown NULL will be returned. This name can be parsed with pa_channel_map_parse()

Since
  0.9.15

## ◆ pa_channel_map_to_pretty_name()

const char * pa_channel_map_to_pretty_name | ( | const pa_channel_map * | map | ) |

Tries to find a human readable text label for this channel mapping, i.e. "Stereo", "Surround 7.1" and so on.

If the channel mapping is unknown NULL will be returned.

Since
  0.9.15

## ◆ pa_channel_map_valid()

int pa_channel_map_valid | ( | const pa_channel_map * | map | ) |

Return non-zero if the specified channel map is considered valid.

## ◆ pa_channel_position_from_string()

pa_channel_position_t pa_channel_position_from_string | ( | const char * | s | ) |

The inverse of pa_channel_position_to_string().

Since
  0.9.16

## ◆ pa_channel_position_to_pretty_string()

const char * pa_channel_position_to_pretty_string | ( | pa_channel_position_t | pos | ) |

Return a human readable text label for the specified channel position.

Since
  0.9.7

## ◆ pa_channel_position_to_string()

const char * pa_channel_position_to_string | ( | pa_channel_position_t | pos | ) |

Return a text label for the specified channel position.