Group PJMEDIA_CONF

group PJMEDIA_CONF

Audio conference bridge implementation.

This describes the conference bridge implementation in PJMEDIA. The conference bridge provides powerful and very efficient mechanism to route the audio flow and mix the audio signal when required.

Some more information about the media flow when conference bridge is used is described in http://www.pjsip.org/trac/wiki/media-flow .

Defines

DEPRECATED_FOR_TICKET_2234
PJMEDIA_CONF_BRIDGE_SIGNATURE

The conference bridge signature in pjmedia_port_info.

PJMEDIA_CONF_SWITCH_SIGNATURE

The audio switchboard signature in pjmedia_port_info.

Typedefs

typedef struct pjmedia_conf pjmedia_conf

Opaque type for conference bridge.

Enums

enum pjmedia_conf_option

Conference port options. The values here can be combined in bitmask to be specified when the conference bridge is created.

Values:

enumerator PJMEDIA_CONF_NO_MIC

Disable audio streams from the microphone device.

enumerator PJMEDIA_CONF_NO_DEVICE

Do not create sound device.

enumerator PJMEDIA_CONF_SMALL_FILTER

Use small filter table when resampling

enumerator PJMEDIA_CONF_USE_LINEAR

Use linear resampling instead of filter based.

Functions

pj_status_t pjmedia_conf_create(pj_pool_t *pool, unsigned max_slots, unsigned sampling_rate, unsigned channel_count, unsigned samples_per_frame, unsigned bits_per_sample, unsigned options, pjmedia_conf **p_conf)

Create conference bridge with the specified parameters. The sampling rate, samples per frame, and bits per sample will be used for the internal operation of the bridge (e.g. when mixing audio frames). However, ports with different configuration may be connected to the bridge. In this case, the bridge is able to perform sampling rate conversion, and buffering in case the samples per frame is different.

For this version of PJMEDIA, only 16bits per sample is supported.

For this version of PJMEDIA, the channel count of the ports MUST match the channel count of the bridge.

Under normal operation (i.e. when PJMEDIA_CONF_NO_DEVICE option is NOT specified), the bridge internally create an instance of sound device and connect the sound device to port zero of the bridge.

If PJMEDIA_CONF_NO_DEVICE options is specified, no sound device will be created in the conference bridge. Application MUST acquire the port interface of the bridge by calling pjmedia_conf_get_master_port(), and connect this port interface to a sound device port by calling pjmedia_snd_port_connect(), or to a master port (pjmedia_master_port) if application doesn’t want to instantiate any sound devices.

The sound device or master port are crucial for the bridge’s operation, because it provides the bridge with necessary clock to process the audio frames periodically. Internally, the bridge runs when get_frame() to port zero is called.

Parameters:
  • pool – Pool to use to allocate the bridge and additional buffers for the sound device.

  • max_slots – Maximum number of slots/ports to be created in the bridge. Note that the bridge internally uses one port for the sound device, so the actual maximum number of ports will be less one than this value.

  • sampling_rate – Set the sampling rate of the bridge. This value is also used to set the sampling rate of the sound device.

  • channel_count – Number of channels in the PCM stream. Normally the value will be 1 for mono, but application may specify a value of 2 for stereo. Note that all ports that will be connected to the bridge MUST have the same number of channels as the bridge.

  • samples_per_frame – Set the number of samples per frame. This value is also used to set the sound device.

  • bits_per_sample – Set the number of bits per sample. This value is also used to set the sound device. Currently only 16bit per sample is supported.

  • options – Bitmask options to be set for the bridge. The options are constructed from pjmedia_conf_option enumeration.

  • p_conf – Pointer to receive the conference bridge instance.

Returns:

PJ_SUCCESS if conference bridge can be created.

pj_status_t pjmedia_conf_destroy(pjmedia_conf *conf)

Destroy conference bridge.

Parameters:

conf – The conference bridge.

Returns:

PJ_SUCCESS on success.

pjmedia_port *pjmedia_conf_get_master_port(pjmedia_conf *conf)

Get the master port interface of the conference bridge. The master port corresponds to the port zero of the bridge. This is only usefull when application wants to manage the sound device by itself, instead of allowing the bridge to automatically create a sound device implicitly.

This function will only return a port interface if PJMEDIA_CONF_NO_DEVICE option was specified when the bridge was created.

Application can connect the port returned by this function to a sound device by calling pjmedia_snd_port_connect().

Parameters:

conf – The conference bridge.

Returns:

The port interface of port zero of the bridge, only when PJMEDIA_CONF_NO_DEVICE options was specified when the bridge was created.

pj_status_t pjmedia_conf_set_port0_name(pjmedia_conf *conf, const pj_str_t *name)

Set master port name.

Parameters:
  • conf – The conference bridge.

  • name – Name to be assigned.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_add_port(pjmedia_conf *conf, pj_pool_t *pool, pjmedia_port *strm_port, const pj_str_t *name, unsigned *p_slot)

Add media port to the conference bridge.

By default, the new conference port will have both TX and RX enabled, but it is not connected to any other ports. Application SHOULD call pjmedia_conf_connect_port() to enable audio transmission and receipt to/from this port.

Once the media port is connected to other port(s) in the bridge, the bridge will continuosly call get_frame() and put_frame() to the port, allowing media to flow to/from the port.

Parameters:
  • conf – The conference bridge.

  • pool – Pool to allocate buffers for this port.

  • strm_port – Stream port interface.

  • name – Optional name for the port. If this value is NULL, the name will be taken from the name in the port info.

  • p_slot – Pointer to receive the slot index of the port in the conference bridge.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_configure_port(pjmedia_conf *conf, unsigned slot, pjmedia_port_op tx, pjmedia_port_op rx)

Change TX and RX settings for the port.

Parameters:
  • conf – The conference bridge.

  • slot – Port number/slot in the conference bridge.

  • tx – Settings for the transmission TO this port.

  • rx – Settings for the receipt FROM this port.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_connect_port(pjmedia_conf *conf, unsigned src_slot, unsigned sink_slot, int adj_level)

Enable unidirectional audio from the specified source slot to the specified sink slot. Application may adjust the level to make signal transmitted from the source slot to the sink slot either louder or more quiet. The level adjustment is calculated with this formula: . Using this, zero indicates no adjustment, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc.

The level adjustment will apply to a specific connection only (i.e. only for the signal from the source to the sink), as compared to pjmedia_conf_adjust_tx_level()/pjmedia_conf_adjust_rx_level() which applies to all signals from/to that port. The signal adjustment will be cumulative, in this following order: signal from the source will be adjusted with the level specified in pjmedia_conf_adjust_rx_level(), then with the level specified via this API, and finally with the level specified to the sink’s pjmedia_conf_adjust_tx_level().

Parameters:
  • conf – The conference bridge.

  • src_slot – Source slot.

  • sink_slot – Sink slot.

  • adj_level – Adjustment level, which must be greater than or equal to -128. A value of zero means there is no level adjustment to be made, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc. See the function description for the formula.

Returns:

PJ_SUCCES on success.

pj_status_t pjmedia_conf_disconnect_port(pjmedia_conf *conf, unsigned src_slot, unsigned sink_slot)

Disconnect unidirectional audio from the specified source to the specified sink slot.

Note that the operation will be done asynchronously, so application should not assume that the port will no longer receive/send audio frame after this function has returned.

Parameters:
  • conf – The conference bridge.

  • src_slot – Source slot.

  • sink_slot – Sink slot.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_disconnect_port_from_sources(pjmedia_conf *conf, unsigned sink_slot)

Disconnect unidirectional audio from all sources to the specified sink slot.

Note that the operation will be done asynchronously, so application should not assume that the port will no longer receive/send audio frame after this function has returned.

Parameters:
  • conf – The conference bridge.

  • sink_slot – Sink slot.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_disconnect_port_from_sinks(pjmedia_conf *conf, unsigned src_slot)

Disconnect unidirectional audio from the specified source to all sink slots.

Note that the operation will be done asynchronously, so application should not assume that the port will no longer receive/send audio frame after this function has returned.

Parameters:
  • conf – The conference bridge.

  • src_slot – Source slot.

Returns:

PJ_SUCCESS on success.

unsigned pjmedia_conf_get_port_count(pjmedia_conf *conf)

Get number of ports currently registered to the conference bridge.

Parameters:

conf – The conference bridge.

Returns:

Number of ports currently registered to the conference bridge.

unsigned pjmedia_conf_get_connect_count(pjmedia_conf *conf)

Get total number of ports connections currently set up in the bridge.

Parameters:

conf – The conference bridge.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_remove_port(pjmedia_conf *conf, unsigned slot)

Remove the specified port from the conference bridge.

Note that the operation will be done asynchronously, so application should not assume that the port will no longer receive/send audio frame after this function has returned.

Parameters:
  • conf – The conference bridge.

  • slot – The port index to be removed.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_enum_ports(pjmedia_conf *conf, unsigned ports[], unsigned *count)

Enumerate occupied ports in the bridge.

Parameters:
  • conf – The conference bridge.

  • ports – Array of port numbers to be filled in.

  • count – On input, specifies the maximum number of ports in the array. On return, it will be filled with the actual number of ports.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_get_port_info(pjmedia_conf *conf, unsigned slot, pjmedia_conf_port_info *info)

Get port info.

Parameters:
  • conf – The conference bridge.

  • slot – Port index.

  • info – Pointer to receive the info.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_get_ports_info(pjmedia_conf *conf, unsigned *size, pjmedia_conf_port_info info[])

Get occupied ports info.

Parameters:
  • conf – The conference bridge.

  • size – On input, contains maximum number of infos to be retrieved. On output, contains the actual number of infos that have been copied.

  • info – Array of info.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_get_signal_level(pjmedia_conf *conf, unsigned slot, unsigned *tx_level, unsigned *rx_level)

Get last signal level transmitted to or received from the specified port. This will retrieve the “real-time” signal level of the audio as they are transmitted or received by the specified port. Application may call this function periodically to display the signal level to a VU meter.

The signal level is an integer value in zero to 255, with zero indicates no signal, and 255 indicates the loudest signal level.

Parameters:
  • conf – The conference bridge.

  • slot – Slot number.

  • tx_level – Optional argument to receive the level of signal transmitted to the specified port (i.e. the direction is from the bridge to the port).

  • rx_level – Optional argument to receive the level of signal received from the port (i.e. the direction is from the port to the bridge).

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_adjust_rx_level(pjmedia_conf *conf, unsigned slot, int adj_level)

Adjust the level of signal received from the specified port. Application may adjust the level to make signal received from the port either louder or more quiet. The level adjustment is calculated with this formula: . Using this, zero indicates no adjustment, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc.

The level adjustment value will stay with the port until the port is removed from the bridge or new adjustment value is set. The current level adjustment value is reported in the media port info when the pjmedia_conf_get_port_info() function is called.

Parameters:
  • conf – The conference bridge.

  • slot – Slot number of the port.

  • adj_level – Adjustment level, which must be greater than or equal to -128. A value of zero means there is no level adjustment to be made, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc. See the function description for the formula.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_adjust_tx_level(pjmedia_conf *conf, unsigned slot, int adj_level)

Adjust the level of signal to be transmitted to the specified port. Application may adjust the level to make signal transmitted to the port either louder or more quiet. The level adjustment is calculated with this formula: . Using this, zero indicates no adjustment, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc.

The level adjustment value will stay with the port until the port is removed from the bridge or new adjustment value is set. The current level adjustment value is reported in the media port info when the pjmedia_conf_get_port_info() function is called.

Parameters:
  • conf – The conference bridge.

  • slot – Slot number of the port.

  • adj_level – Adjustment level, which must be greater than or equal to -128. A value of zero means there is no level adjustment to be made, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc. See the function description for the formula.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_conf_adjust_conn_level(pjmedia_conf *conf, unsigned src_slot, unsigned sink_slot, int adj_level)

Adjust the level of signal to be transmitted from the source slot to the sink slot. Application may adjust the level to make signal transmitted from the source slot to the sink slot either louder or more quiet. The level adjustment is calculated with this formula: . Using this, zero indicates no adjustment, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc.

The level adjustment value will stay with the connection until the connection is removed or new adjustment value is set. The current level adjustment value is reported in the media port info when the pjmedia_conf_get_port_info() function is called.

Parameters:
  • conf – The conference bridge.

  • src_slot – Source slot.

  • sink_slot – Sink slot.

  • adj_level – Adjustment level, which must be greater than or equal to -128. A value of zero means there is no level adjustment to be made, the value -128 will mute the signal, and the value of +128 will make the signal 100% louder, +256 will make it 200% louder, etc. See the function description for the formula.

Returns:

PJ_SUCCESS on success.

struct pjmedia_conf_port_info
#include <conference.h>

Conference port info.

Public Members

unsigned slot

Slot number.

pj_str_t name

Port name.

pjmedia_format format

Format.

pjmedia_port_op tx_setting

Transmit settings.

pjmedia_port_op rx_setting

Receive settings.

unsigned listener_cnt

Number of listeners.

unsigned *listener_slots

Array of listeners.

unsigned *listener_adj_level

Array of listeners’ level adjustment

unsigned transmitter_cnt

Number of transmitter.

unsigned clock_rate

Clock rate of the port.

unsigned channel_count

Number of channels.

unsigned samples_per_frame

Samples per frame

unsigned bits_per_sample

Bits per sample.

int tx_adj_level

Tx level adjustment.

int rx_adj_level

Rx level adjustment.