ALSA project - the C library reference: External Filter plugin SDK

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External Filter plugin SDK
External PCM plugin SDK

## Data Structures
struct | snd_pcm_extplug_t
struct | snd_pcm_extplug_callback_t

## Macros
#define | SND_PCM_EXTPLUG_VERSION_MAJOR 1
#define | SND_PCM_EXTPLUG_VERSION_MINOR 0
#define | SND_PCM_EXTPLUG_VERSION_TINY 2
#define | SND_PCM_EXTPLUG_VERSION

## Typedefs
typedef snd_pcm_extplug | snd_pcm_extplug_t
typedef snd_pcm_extplug_callback | snd_pcm_extplug_callback_t

## Enumerations
enum | { SND_PCM_EXTPLUG_HW_FORMAT, SND_PCM_EXTPLUG_HW_CHANNELS, SND_PCM_EXTPLUG_HW_PARAMS }

## Functions
int | snd_pcm_extplug_create (snd_pcm_extplug_t *ext, const char *name, snd_config_t *root, snd_config_t *slave_conf, snd_pcm_stream_t stream, int mode)
| Create an extplug instance. More...
int | snd_pcm_extplug_delete (snd_pcm_extplug_t *ext)
| Delete the extplug instance. More...
void | snd_pcm_extplug_params_reset (snd_pcm_extplug_t *ext)
| Reset extplug parameters. More...
int | snd_pcm_extplug_set_param_list (snd_pcm_extplug_t *extplug, int type, unsigned int num_list, const unsigned int *list)
| Set master parameter as the list. More...
int | snd_pcm_extplug_set_param_minmax (snd_pcm_extplug_t *extplug, int type, unsigned int min, unsigned int max)
| Set master parameter as the min/max values. More...
int | snd_pcm_extplug_set_slave_param_list (snd_pcm_extplug_t *extplug, int type, unsigned int num_list, const unsigned int *list)
| Set slave parameter as the list. More...
int | snd_pcm_extplug_set_slave_param_minmax (snd_pcm_extplug_t *extplug, int type, unsigned int min, unsigned int max)
| Set slave parameter as the min/max values. More...
int | snd_pcm_extplug_set_param_link (snd_pcm_extplug_t *extplug, int type, int keep_link)
| Keep the client and slave format/channels the same if requested. This is for example useful if this extplug does not support any channel conversion. More...

## Detailed Description

See the PCM (digital audio) interface page for more details.

## Macro Definition Documentation

#define SND_PCM_EXTPLUG_VERSION

Value:
((SND_PCM_EXTPLUG_VERSION_MAJOR<<16) |\
(SND_PCM_EXTPLUG_VERSION_MINOR<<8) |\
(SND_PCM_EXTPLUG_VERSION_TINY))
SND_PCM_EXTPLUG_VERSION_TINY
#define SND_PCM_EXTPLUG_VERSION_TINY
Definition: pcm_extplug.h:63
SND_PCM_EXTPLUG_VERSION_MAJOR
#define SND_PCM_EXTPLUG_VERSION_MAJOR
Definition: pcm_extplug.h:61
SND_PCM_EXTPLUG_VERSION_MINOR
#define SND_PCM_EXTPLUG_VERSION_MINOR
Definition: pcm_extplug.h:62

Filter-plugin protocol version

#define SND_PCM_EXTPLUG_VERSION_MAJOR 1

Protocol major version

#define SND_PCM_EXTPLUG_VERSION_MINOR 0

Protocol minor version

#define SND_PCM_EXTPLUG_VERSION_TINY 2

Protocol tiny version

## Typedef Documentation

typedef struct snd_pcm_extplug_callback snd_pcm_extplug_callback_t

Callback table of extplug

typedef struct snd_pcm_extplug snd_pcm_extplug_t

Handle of external filter plugin

## Enumeration Type Documentation

anonymous enum

hw constraints for extplug

Enumerator
SND_PCM_EXTPLUG_HW_FORMAT | format
SND_PCM_EXTPLUG_HW_CHANNELS | channels
SND_PCM_EXTPLUG_HW_PARAMS | max number of hw constraints

## Function Documentation

int snd_pcm_extplug_create | ( | snd_pcm_extplug_t * | extplug,
|  | const char * | name,
|  | snd_config_t * | root,
|  | snd_config_t * | slave_conf,
|  | snd_pcm_stream_t | stream,
|  | int | mode
| ) |  |

Create an extplug instance.

Parameters

  extplug | the extplug handle
  name | name of the PCM
  root | configuration tree root
  slave_conf | slave configuration root
  stream | stream direction
  mode | PCM open mode

Returns
  0 if successful, or a negative error code

Creates the extplug instance based on the given handle. The slave_conf argument is mandatory, and usually taken from the config tree of the PCM plugin as "slave" config value. name, root, stream and mode arguments are the values used for opening the PCM.

The callback is the mandatory field of extplug handle. At least, start, stop and pointer callbacks must be set before calling this function.

int snd_pcm_extplug_delete | ( | snd_pcm_extplug_t * | extplug | ) |

Delete the extplug instance.

Parameters

  extplug | the extplug handle to delete

Returns
  0 if successful, or a negative error code

The destructor of extplug instance. Closes the PCM and deletes the associated resources.

void snd_pcm_extplug_params_reset | ( | snd_pcm_extplug_t * | extplug | ) |

Reset extplug parameters.

Parameters

  extplug | the extplug handle

Resets the all parameters for the given extplug handle.

int snd_pcm_extplug_set_param_link | ( | snd_pcm_extplug_t * | extplug,
|  | int | type,
|  | int | keep_link
| ) |  |

Keep the client and slave format/channels the same if requested. This is for example useful if this extplug does not support any channel conversion.

Parameters

  extplug | the extplug handle
  type | parameter type
  keep_link | if 1 the parameter identified by type will be kept the same for the client and slave PCM of this extplug

Returns
  0 if successful, or a negative error code

int snd_pcm_extplug_set_param_list | ( | snd_pcm_extplug_t * | extplug,
|  | int | type,
|  | unsigned int | num_list,
|  | const unsigned int * | list
| ) |  |

Set master parameter as the list.

Parameters

  extplug | the extplug handle
  type | parameter type
  num_list | number of available values
  list | the list of available values

Returns
  0 if successful, or a negative error code

Sets the master parameter as the list. The available values of the given parameter type of this PCM (as input) is restricted to the ones of the given list.

int snd_pcm_extplug_set_param_minmax | ( | snd_pcm_extplug_t * | extplug,
|  | int | type,
|  | unsigned int | min,
|  | unsigned int | max
| ) |  |

Set master parameter as the min/max values.

Parameters

  extplug | the extplug handle
  type | parameter type
  min | the minimum value
  max | the maximum value

Returns
  0 if successful, or a negative error code

Sets the master parameter as the min/max values. The available values of the given parameter type of this PCM (as input) is restricted between the given minimum and maximum values.

int snd_pcm_extplug_set_slave_param_list | ( | snd_pcm_extplug_t * | extplug,
|  | int | type,
|  | unsigned int | num_list,
|  | const unsigned int * | list
| ) |  |

Set slave parameter as the list.

Parameters

  extplug | the extplug handle
  type | parameter type
  num_list | number of available values
  list | the list of available values

Returns
  0 if successful, or a negative error code

Sets the slave parameter as the list. The available values of the given parameter type of the slave PCM is restricted to the ones of the given list.

int snd_pcm_extplug_set_slave_param_minmax | ( | snd_pcm_extplug_t * | extplug,
|  | int | type,
|  | unsigned int | min,
|  | unsigned int | max
| ) |  |

Set slave parameter as the min/max values.

Parameters

  extplug | the extplug handle
  type | parameter type
  min | the minimum value
  max | the maximum value

Returns
  0 if successful, or a negative error code

Sets the slave parameter as the min/max values. The available values of the given parameter type of the slave PCM is restricted between the given minimum and maximum values.