mediastreamer2: Filter API - manage mediastreamer2 filters.

mediastreamer2 2.7.3

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Defines | Typedefs | Enumerations | Functions
Filter API - manage mediastreamer2 filters.
Mediastreamer2's base APIs

Filter API to manage mediastreamer2 filters. More...

## Defines
#define | MS_FILTER_SET_SAMPLE_RATE MS_FILTER_BASE_METHOD(0,int)
#define | MS_FILTER_GET_SAMPLE_RATE MS_FILTER_BASE_METHOD(1,int)
#define | MS_FILTER_SET_BITRATE MS_FILTER_BASE_METHOD(2,int)
#define | MS_FILTER_GET_BITRATE MS_FILTER_BASE_METHOD(3,int)
#define | MS_FILTER_ADD_FMTP MS_FILTER_BASE_METHOD(7,const char)
#define | MS_FILTER_GET_LATENCY MS_FILTER_BASE_METHOD(11,int)
## Typedefs
typedef void(* | MSFilterFunc )(struct _MSFilter *f)
typedef int(* | MSFilterMethodFunc )(struct _MSFilter *f, void *arg)
typedef void(* | MSFilterNotifyFunc )(void *userdata, struct _MSFilter *f, unsigned int id, void *arg)
typedef struct _MSFilterMethod | MSFilterMethod
typedef enum _MSFilterCategory | MSFilterCategory
typedef struct _MSFilterDesc | MSFilterDesc
typedef struct _MSFilter | MSFilter
typedef struct _MSConnectionPoint | MSConnectionPoint
typedef struct _MSConnectionHelper | MSConnectionHelper
## Enumerations
enum | _MSFilterCategory { MS_FILTER_OTHER, MS_FILTER_ENCODER, MS_FILTER_DECODER }
## Functions
void | ms_filter_register (MSFilterDesc *desc)
MSFilterDesc * | ms_filter_get_encoder (const char *mime)
MSFilterDesc * | ms_filter_get_decoder (const char *mime)
MSFilterDesc * | ms_filter_lookup_by_name (const char *filter_name)
MSFilter * | ms_filter_create_encoder (const char *mime)
MSFilter * | ms_filter_create_decoder (const char *mime)
bool_t | ms_filter_codec_supported (const char *mime)
MSFilter * | ms_filter_new (MSFilterId id)
MSFilter * | ms_filter_new_from_name (const char *name)
MSFilter * | ms_filter_new_from_desc (MSFilterDesc *desc)
int | ms_filter_link (MSFilter *f1, int pin1, MSFilter *f2, int pin2)
int | ms_filter_unlink (MSFilter *f1, int pin1, MSFilter *f2, int pin2)
int | ms_filter_call_method (MSFilter *f, unsigned int id, void *arg)
int | ms_filter_call_method_noarg (MSFilter *f, unsigned int id)
bool_t | ms_filter_has_method (MSFilter *f, unsigned int id)
void | ms_filter_set_notify_callback (MSFilter *f, MSFilterNotifyFunc fn, void *userdata)
MSFilterId | ms_filter_get_id (MSFilter *f)
MSList * | ms_filter_find_neighbours (MSFilter *me)
void | ms_filter_destroy (MSFilter *f)
void | ms_connection_helper_start (MSConnectionHelper *h)
int | ms_connection_helper_link (MSConnectionHelper *h, MSFilter *f, int inpin, int outpin)
| Enter a MSFilter to be connected into the MSConnectionHelper object.
int | ms_connection_helper_unlink (MSConnectionHelper *h, MSFilter *f, int inpin, int outpin)
| Enter a MSFilter to be disconnected into the MSConnectionHelper object. Process exactly the same way as ms_connection_helper_link() but calls ms_filter_unlink() on the entered filters.
void | ms_filter_enable_statistics (bool_t enabled)
| Enable processing time measurements statistics for filters.
void | ms_filter_reset_statistics (void)
| Reset processing time statistics for filters.
const MSList * | ms_filter_get_statistics (void)
| Retrieves statistics for running filters. Returns a list of MSFilterStats.
void | ms_filter_log_statistics (void)
| Logs runtime statistics for running filters.

## Detailed Description

Filter API to manage mediastreamer2 filters.

This section documents the API needed to create, link, unlink, find and destroy filters.

It also provides definitions if you wish to implement your own filters.

## Define Documentation

#define MS_FILTER_SET_SAMPLE_RATE MS_FILTER_BASE_METHOD(0,int)

some MSFilter base generic methods: Set filter output/input sampling frequency in hertz

#define MS_FILTER_GET_SAMPLE_RATE MS_FILTER_BASE_METHOD(1,int)

Get filter output/input sampling frequency in hertz

#define MS_FILTER_SET_BITRATE MS_FILTER_BASE_METHOD(2,int)

Set filter output network bitrate in bit per seconds, this value include IP+UDP+RTP overhead

#define MS_FILTER_GET_BITRATE MS_FILTER_BASE_METHOD(3,int)

Get filter output network bitrate in bit per seconds, this value include IP+UDP+RTP overhead

#define MS_FILTER_ADD_FMTP MS_FILTER_BASE_METHOD(7,const char)

Set codec dependent attributes as taken from the SDP

#define MS_FILTER_GET_LATENCY MS_FILTER_BASE_METHOD(11,int)

Filters can return their latency in milliseconds (if known) using this method:

## Typedef Documentation

MSFilterFunc

Structure for filter's methods (init, preprocess, process, postprocess, uninit).

MSFilterMethodFunc

Structure for filter's methods used to set filter's options.

MSFilterNotifyFunc

Structure for filter's methods used as a callback to notify events.

MSFilterMethod

Structure for holding filter's methods to set filter's options.

MSFilterCategory

Structure to describe filter's category.

         MS_FILTER_OTHER
         MS_FILTER_ENCODER
         MS_FILTER_DECODER

MSFilterDesc

Structure for filter's description.

MSFilter

Structure to create/link/unlink/destroy filter's object.

MSConnectionPoint

Structure that represents a connection point of a MSFilter

MSConnectionHelper

Structure that holds data when using the ms_connection_helper_* functions.

## Enumeration Type Documentation

enum _MSFilterCategory

Filter's category

Enumerator:

  MS_FILTER_OTHER | others
  MS_FILTER_ENCODER | used by encoders
  MS_FILTER_DECODER | used by decoders

## Function Documentation

void ms_filter_register | ( | MSFilterDesc * | desc | ) |

Register a filter description. (plugins use only!)

When you build your own plugin, this method will add the encoder or decoder to the internal list of supported codec. Then, this plugin can be used transparently from the application.

ms_filter_get_encoder, ms_filter_get_decoder, ms_filter_create_encoder, ms_filter_create_decoder and ms_filter_codec_supported can then be used as if the codec was internally. supported.

Parameters:

  desc | a filter description.

MSFilterDesc* ms_filter_get_encoder | ( | const char * | mime | ) |

Retrieve encoders according to codec name.

Internal supported codecs: PCMU, PCMA, speex, gsm Existing Public plugins: iLBC

Parameters:

  mime | A string indicating the codec.

Returns: a MSFilterDesc if successfull, NULL otherwise.

MSFilterDesc* ms_filter_get_decoder | ( | const char * | mime | ) |

Retrieve decoders according to codec name.

Internal supported codecs: PCMU, PCMA, speex, gsm Existing Public plugins: iLBC

Parameters:

  mime | A string indicating the codec.

Returns: a MSFilterDesc if successfull, NULL otherwise.

MSFilterDesc* ms_filter_lookup_by_name | ( | const char * | filter_name | ) |

Lookup a mediastreamer2 filter using its name. If found, the descriptor (MSFilterDesc) is returned. This descriptor can be used to instanciate the filter using ms_filter_new_from_desc() This function can be useful to query the presence of a filter loaded as a plugin, for example.

Parameters:

  name | The filter name.

MSFilter* ms_filter_create_encoder | ( | const char * | mime | ) |

Create encoder filter according to codec name.

Internal supported codecs: PCMU, PCMA, speex, gsm Existing Public plugins: iLBC

Parameters:

  mime | A string indicating the codec.

Returns: a MSFilter if successfull, NULL otherwise.

MSFilter* ms_filter_create_decoder | ( | const char * | mime | ) |

Create decoder filter according to codec name.

Internal supported codecs: PCMU, PCMA, speex, gsm Existing Public plugins: iLBC

Parameters:

  mime | A string indicating the codec.

Returns: a MSFilter if successfull, NULL otherwise.

bool_t ms_filter_codec_supported | ( | const char * | mime | ) |

Check if a encode or decode filter exists for a codec name.

Internal supported codecs: PCMU, PCMA, speex, gsm Existing Public plugins: iLBC

Parameters:

  mime | A string indicating the codec.

Returns: TRUE if successfull, FALSE otherwise.

MSFilter* ms_filter_new | ( | MSFilterId | id | ) |

Create decoder filter according to a filter's MSFilterId.

Parameters:

  id | A MSFilterId identifier for the filter.

Returns: a MSFilter if successfull, NULL otherwise.

MSFilter* ms_filter_new_from_name | ( | const char * | name | ) |

Create decoder filter according to a filter's name.

Parameters:

  name | A name for the filter.

Returns: a MSFilter if successfull, NULL otherwise.

MSFilter* ms_filter_new_from_desc | ( | MSFilterDesc * | desc | ) |

Create decoder filter according to a filter's description.

The primary use is to create your own filter's in your application and avoid registration inside mediastreamer2.

Parameters:

  desc | A MSFilterDesc for the filter.

Returns: a MSFilter if successfull, NULL otherwise.

int ms_filter_link | ( | MSFilter * | f1,
|  | int | pin1,
|  | MSFilter * | f2,
|  | int | pin2
| ) |  |

Link one OUTPUT pin from a filter to an INPUT pin of another filter.

All data coming from the OUTPUT pin of one filter will be distributed to the INPUT pin of the second filter.

Parameters:

  f1 | A MSFilter object containing the OUTPUT pin
  pin1 | An index of an OUTPUT pin.
  f2 | A MSFilter object containing the INPUT pin
  pin2 | An index of an INPUT pin.

Returns: 0 if sucessful, -1 otherwise.

int ms_filter_unlink | ( | MSFilter * | f1,
|  | int | pin1,
|  | MSFilter * | f2,
|  | int | pin2
| ) |  |

Unlink one OUTPUT pin from a filter to an INPUT pin of another filter.

Parameters:

  f1 | A MSFilter object containing the OUTPUT pin
  pin1 | An index of an OUTPUT pin.
  f2 | A MSFilter object containing the INPUT pin
  pin2 | An index of an INPUT pin.

Returns: 0 if sucessful, -1 otherwise.

int ms_filter_call_method | ( | MSFilter * | f,
|  | unsigned int | id,
|  | void * | arg
| ) |  |

Call a filter's method to set or get options.

Parameters:

  f | A MSFilter object.
  id | A private filter ID for the option.
  arg | A private user data for the filter.

Returns: 0 if successfull, -1 otherwise.

int ms_filter_call_method_noarg | ( | MSFilter * | f,
|  | unsigned int | id
| ) |  |

Call a filter's method to set options.

Parameters:

  f | A MSFilter object.
  id | A method ID.

Returns: 0 if successfull, -1 otherwise.

bool_t ms_filter_has_method | ( | MSFilter * | f,
|  | unsigned int | id
| ) |  |

Returns whether the filter implements a given method

Parameters:

  f | A MSFilter object.
  id | A method ID.

Returns: 0 if successfull, -1 otherwise.

void ms_filter_set_notify_callback | ( | MSFilter * | f,
|  | MSFilterNotifyFunc | fn,
|  | void * | userdata
| ) |  |

Set a callback on filter's to be informed of private filter's event. This callback is called from the filter's MSTicker, unless a global event queue is created to receive all filter's notification asynchronously. See ms_event_queue_new() for details.

Parameters:

  f | A MSFilter object.
  fn | A MSFilterNotifyFunc that will be called.
  userdata | A pointer to private data.

MSFilterId ms_filter_get_id | ( | MSFilter * | f | ) |

Get MSFilterId's filter.

Parameters:

  f | A MSFilter object.

Returns: MSFilterId if successfull, -1 otherwise.

MSList* ms_filter_find_neighbours | ( | MSFilter * | me | ) |

Obtain the list of current filter's neighbours, ie filters that are part of same graph.

Returns: a MSList of MSFilter, that needs to be freed by the caller when no more needed.

void ms_filter_destroy | ( | MSFilter * | f | ) |

Destroy a filter object.

Parameters:

  f | A MSFilter object.

void ms_connection_helper_start | ( | MSConnectionHelper * | h | ) |

Initialize a MSConnectionHelper.

Parameters:

  h | A MSConnectionHelper, usually (but not necessarily) on stack

int ms_connection_helper_link | ( | MSConnectionHelper * | h,
|  | MSFilter * | f,
|  | int | inpin,
|  | int | outpin
| ) |  |

Enter a MSFilter to be connected into the MSConnectionHelper object.

This functions enters a MSFilter to be connected into the MSConnectionHelper object and connects it to the last entered if not the first one. The MSConnectionHelper is useful to reduce the amount of code necessary to create graphs in case the connections are made in an ordered manner and some filters are present conditionally in graphs. For example, instead of writing

     ms_filter_link(f1,0,f2,1);
     ms_filter_link(f2,0,f3,0);
     ms_filter_link(f3,1,f4,0);

You can write:

     MSConnectionHelper h;
     ms_connection_helper_start(&h);
     ms_connection_helper_link(&h,f1,-1,0);
     ms_connection_helper_link(&h,f2,1,0);
     ms_connection_helper_link(&h,f3,0,1);
     ms_connection_helper_link(&h,f4,0,-1);

Which is a bit longer to write here, but now imagine f2 needs to be present in the graph only in certain conditions: in the first case you have rewrite the two first lines, in the second case you just need to replace the fourth line by:

     if (my_condition) ms_connection_helper_link(&h,f2,1,0);

Parameters:

  h | a connection helper
  f | a MSFilter
  inpin | an input pin number with which the MSFilter needs to connect to previously entered MSFilter
  outpin | an output pin number with which the MSFilter needs to be connected to the next entered MSFilter

Returns: the return value of ms_filter_link() that is called internally to this function.