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

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_add_passive_port(pjmedia_conf *conf, pj_pool_t *pool, const pj_str_t *name, unsigned clock_rate, unsigned channel_count, unsigned samples_per_frame, unsigned bits_per_sample, unsigned options, unsigned *p_slot, pjmedia_port **p_port)

This API has been deprecated since 1.3 and will be removed in the future release, use Media channel splitter/combiner instead.

Create and add a passive media port to the conference bridge. Unlike “normal” media port that is added with pjmedia_conf_add_port(), media port created with this function will not have its get_frame() and put_frame() called by the bridge; instead, application MUST continuosly call these functions to the port, to allow media to flow from/to the port.

Upon return of this function, application will be given two objects: the slot number of the port in the bridge, and pointer to the media port where application MUST start calling get_frame() and put_frame() to the port.

Parameters

  • conf – The conference bridge.

  • pool – Pool to allocate buffers etc for this port.

  • name – Name to be assigned to the port.

  • clock_rate – Clock rate/sampling rate.

  • channel_count – Number of channels.

  • samples_per_frame – Number of samples per frame.

  • bits_per_sample – Number of bits per sample.

  • options – Options (should be zero at the moment).

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

  • p_port – Pointer to receive the port instance.

Returns

PJ_SUCCESS on success, or the appropriate error code.

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 level)

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

Parameters

  • conf – The conference bridge.

  • src_slot – Source slot.

  • sink_slot – Sink slot.

  • level – This argument is reserved for future improvements where it is possible to adjust the level of signal transmitted in a specific connection. For now, this argument MUST be zero.

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.

Parameters

  • conf – The conference bridge.

  • src_slot – Source slot.

  • sink_slot – Sink 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.

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.

struct pjmedia_conf_port_info
#include <conference.h>

Conference port info.