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* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2007 - 2009, Digium, Inc.
*
* Joshua Colp <jcolp@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
/*! \file
* \brief Channel Bridging API
* \author Joshua Colp <jcolp@digium.com>
* \ref AstBridging
*/
/*!
* \page AstBridging Channel Bridging API
*
* The purpose of this API is to provide an easy and flexible way to bridge
* channels of different technologies with different features.
*
* Bridging technologies provide the mechanism that do the actual handling
* of frames between channels. They provide capability information, codec information,
* and preference value to assist the bridging core in choosing a bridging technology when
* creating a bridge. Different bridges may use different bridging technologies based on needs
* but once chosen they all operate under the same premise; they receive frames and send frames.
*
* Bridges are a combination of bridging technology, channels, and features. A
* developer creates a new bridge based on what they are currently expecting to do
* with it or what they will do with it in the future. The bridging core determines what
* available bridging technology will best fit the requirements and creates a new bridge.
* Once created, channels can be added to the bridge in a blocking or non-blocking fashion.
*
* Features are such things as channel muting or DTMF based features such as attended transfer,
* blind transfer, and hangup. Feature information must be set at the most granular level, on
* the channel. While you can use features on a global scope the presence of a feature structure
* on the channel will override the global scope. An example would be having the bridge muted
* at global scope and attended transfer enabled on a channel. Since the channel itself is not muted
* it would be able to speak.
*
* Feature hooks allow a developer to tell the bridging core that when a DTMF string
* is received from a channel a callback should be called in their application. For
* example, a conference bridge application may want to provide an IVR to control various
* settings on the conference bridge. This can be accomplished by attaching a feature hook
* that calls an IVR function when a DTMF string is entered.
*
*/
#ifndef _ASTERISK_BRIDGING_H
#define _ASTERISK_BRIDGING_H
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#include "asterisk/bridging_features.h"
#include "asterisk/dsp.h"
/*! \brief Capabilities for a bridge technology */
enum ast_bridge_capability {
/*! Bridge is only capable of mixing 2 channels */
AST_BRIDGE_CAPABILITY_1TO1MIX = (1 << 1),
/*! Bridge is capable of mixing 2 or more channels */
AST_BRIDGE_CAPABILITY_MULTIMIX = (1 << 2),
/*! Bridge should natively bridge two channels if possible */
AST_BRIDGE_CAPABILITY_NATIVE = (1 << 3),
/*! Bridge should run using the multithreaded model */
AST_BRIDGE_CAPABILITY_MULTITHREADED = (1 << 4),
/*! Bridge should run a central bridge thread */
AST_BRIDGE_CAPABILITY_THREAD = (1 << 5),
/*! Bridge technology can do video mixing (or something along those lines) */
AST_BRIDGE_CAPABILITY_VIDEO = (1 << 6),
/*! Bridge technology can optimize things based on who is talking */
AST_BRIDGE_CAPABILITY_OPTIMIZE = (1 << 7),
};
/*! \brief State information about a bridged channel */
enum ast_bridge_channel_state {
/*! Waiting for a signal */
AST_BRIDGE_CHANNEL_STATE_WAIT = 0,
/*! Bridged channel has ended itself (it has hung up) */
AST_BRIDGE_CHANNEL_STATE_END,
/*! Bridged channel should be hung up */
AST_BRIDGE_CHANNEL_STATE_HANGUP,
/*! Bridged channel should be removed from the bridge without being hung up */
AST_BRIDGE_CHANNEL_STATE_DEPART,
/*! Bridged channel is executing a feature hook */
AST_BRIDGE_CHANNEL_STATE_FEATURE,
/*! Bridged channel is sending a DTMF stream out */
AST_BRIDGE_CHANNEL_STATE_DTMF,
/*! Bridged channel began talking */
AST_BRIDGE_CHANNEL_STATE_START_TALKING,
/*! Bridged channel has stopped talking */
AST_BRIDGE_CHANNEL_STATE_STOP_TALKING,
};
/*! \brief Return values for bridge technology write function */
enum ast_bridge_write_result {
/*! Bridge technology wrote out frame fine */
AST_BRIDGE_WRITE_SUCCESS = 0,
/*! Bridge technology attempted to write out the frame but failed */
AST_BRIDGE_WRITE_FAILED,
/*! Bridge technology does not support writing out a frame of this type */
AST_BRIDGE_WRITE_UNSUPPORTED,
};
struct ast_bridge_technology;
struct ast_bridge;
/*!
* \brief Structure specific to bridge technologies capable of
* performing talking optimizations.
*/
struct ast_bridge_tech_optimizations {
/*! The amount of time in ms that talking must be detected before
* the dsp determines that talking has occurred */
unsigned int talking_threshold;
/*! The amount of time in ms that silence must be detected before
* the dsp determines that talking has stopped */
unsigned int silence_threshold;
/*! Whether or not the bridging technology should drop audio
* detected as silence from the mix. */
unsigned int drop_silence:1;
};
/*!
* \brief Structure that contains information regarding a channel in a bridge
*/
struct ast_bridge_channel {
/*! Lock to protect this data structure */
ast_mutex_t lock;
/*! Condition, used if we want to wake up a thread waiting on the bridged channel */
ast_cond_t cond;
/*! Current bridged channel state */
enum ast_bridge_channel_state state;
/*! Asterisk channel participating in the bridge */
struct ast_channel *chan;
/*! Asterisk channel we are swapping with (if swapping) */
struct ast_channel *swap;
/*! Bridge this channel is participating in */
struct ast_bridge *bridge;
/*! Private information unique to the bridge technology */
void *bridge_pvt;
/*! Thread handling the bridged channel */
pthread_t thread;
/*! Additional file descriptors to look at */
int fds[4];
/*! Bit to indicate whether the channel is suspended from the bridge or not */
unsigned int suspended:1;
/*! Bit to indicate if a imparted channel is allowed to get hungup after leaving the bridge by the bridging core. */
unsigned int allow_impart_hangup:1;
/*! Features structure for features that are specific to this channel */
struct ast_bridge_features *features;
/*! Technology optimization parameters used by bridging technologies capable of
* optimizing based upon talk detection. */
struct ast_bridge_tech_optimizations tech_args;
/*! Queue of DTMF digits used for DTMF streaming */
char dtmf_stream_q[8];
/*! Call ID associated with bridge channel */
struct ast_callid *callid;
/*! Linked list information */
AST_LIST_ENTRY(ast_bridge_channel) entry;
};
enum ast_bridge_video_mode_type {
/*! Video is not allowed in the bridge */
AST_BRIDGE_VIDEO_MODE_NONE = 0,
/*! A single user is picked as the only distributed of video across the bridge */
AST_BRIDGE_VIDEO_MODE_SINGLE_SRC,
/*! A single user's video feed is distributed to all bridge channels, but
* that feed is automatically picked based on who is talking the most. */
AST_BRIDGE_VIDEO_MODE_TALKER_SRC,
};
/*! This is used for both SINGLE_SRC mode to set what channel
* should be the current single video feed */
struct ast_bridge_video_single_src_data {
/*! Only accept video coming from this channel */
struct ast_channel *chan_vsrc;
};
/*! This is used for both SINGLE_SRC_TALKER mode to set what channel
* should be the current single video feed */
struct ast_bridge_video_talker_src_data {
/*! Only accept video coming from this channel */
struct ast_channel *chan_vsrc;
int average_talking_energy;
/*! Current talker see's this person */
struct ast_channel *chan_old_vsrc;
};
struct ast_bridge_video_mode {
enum ast_bridge_video_mode_type mode;
/* Add data for all the video modes here. */
union {
struct ast_bridge_video_single_src_data single_src_data;
struct ast_bridge_video_talker_src_data talker_src_data;
} mode_data;
};
/*!
* \brief Structure that contains information about a bridge
*/
struct ast_bridge {
/*! Number of channels participating in the bridge */
int num;
/*! The video mode this bridge is using */
struct ast_bridge_video_mode video_mode;
/*! The internal sample rate this bridge is mixed at when multiple channels are being mixed.
* If this value is 0, the bridge technology may auto adjust the internal mixing rate. */
unsigned int internal_sample_rate;
/*! The mixing interval indicates how quickly the bridges internal mixing should occur
* for bridge technologies that mix audio. When set to 0, the bridge tech must choose a
* default interval for itself. */
unsigned int internal_mixing_interval;
/*! Bit to indicate that the bridge thread is waiting on channels in the bridge array */
unsigned int waiting:1;
/*! Bit to indicate the bridge thread should stop */
unsigned int stop:1;
/*! Bit to indicate the bridge thread should refresh itself */
unsigned int refresh:1;
/*! Bridge flags to tweak behavior */
struct ast_flags feature_flags;
/*! Bridge technology that is handling the bridge */
struct ast_bridge_technology *technology;
/*! Private information unique to the bridge technology */
void *bridge_pvt;
/*! Thread running the bridge */
pthread_t thread;
/*! Enabled features information */
struct ast_bridge_features features;
/*! Array of channels that the bridge thread is currently handling */
struct ast_channel **array;
/*! Number of channels in the above array */
size_t array_num;
/*! Number of channels the array can handle */
size_t array_size;
/*! Call ID associated with the bridge */
struct ast_callid *callid;
/*! Linked list of channels participating in the bridge */
AST_LIST_HEAD_NOLOCK(, ast_bridge_channel) channels;
};
/*! \brief Create a new bridge
*
* \param capabilities The capabilities that we require to be used on the bridge
* \param flags Flags that will alter the behavior of the bridge
*
* \retval a pointer to a new bridge on success
* \retval NULL on failure
*
* Example usage:
*
* \code
* struct ast_bridge *bridge;
* bridge = ast_bridge_new(AST_BRIDGE_CAPABILITY_1TO1MIX, AST_BRIDGE_FLAG_DISSOLVE);
* \endcode
*
* This creates a simple two party bridge that will be destroyed once one of
* the channels hangs up.
*/
struct ast_bridge *ast_bridge_new(uint32_t capabilities, int flags);
/*!
* \brief Lock the bridge.
*
* \param bridge Bridge to lock
*
* \return Nothing
*/
#define ast_bridge_lock(bridge) _ast_bridge_lock(bridge, __FILE__, __PRETTY_FUNCTION__, __LINE__, #bridge)
static inline void _ast_bridge_lock(struct ast_bridge *bridge, const char *file, const char *function, int line, const char *var)
{
__ao2_lock(bridge, AO2_LOCK_REQ_MUTEX, file, function, line, var);
}
/*!
* \brief Unlock the bridge.
*
* \param bridge Bridge to unlock
*
* \return Nothing
*/
#define ast_bridge_unlock(bridge) _ast_bridge_unlock(bridge, __FILE__, __PRETTY_FUNCTION__, __LINE__, #bridge)
static inline void _ast_bridge_unlock(struct ast_bridge *bridge, const char *file, const char *function, int line, const char *var)
{
__ao2_unlock(bridge, file, function, line, var);
}
/*! \brief See if it is possible to create a bridge
*
* \param capabilities The capabilities that the bridge will use
*
* \retval 1 if possible
* \retval 0 if not possible
*
* Example usage:
*
* \code
* int possible = ast_bridge_check(AST_BRIDGE_CAPABILITY_1TO1MIX);
* \endcode
*
* This sees if it is possible to create a bridge capable of bridging two channels
* together.
*/
int ast_bridge_check(uint32_t capabilities);
/*! \brief Destroy a bridge
*
* \param bridge Bridge to destroy
*
* \retval 0 on success
* \retval -1 on failure
*
* Example usage:
*
* \code
* ast_bridge_destroy(bridge);
* \endcode
*
* This destroys a bridge that was previously created using ast_bridge_new.
*/
int ast_bridge_destroy(struct ast_bridge *bridge);
/*! \brief Join (blocking) a channel to a bridge
*
* \param bridge Bridge to join
* \param chan Channel to join
* \param swap Channel to swap out if swapping
* \param features Bridge features structure
* \param (Optional) Bridging tech optimization parameters for this channel.
*
* \retval state that channel exited the bridge with
*
* Example usage:
*
* \code
* ast_bridge_join(bridge, chan, NULL, NULL);
* \endcode
*
* This adds a channel pointed to by the chan pointer to the bridge pointed to by
* the bridge pointer. This function will not return until the channel has been
* removed from the bridge, swapped out for another channel, or has hung up.
*
* If this channel will be replacing another channel the other channel can be specified
* in the swap parameter. The other channel will be thrown out of the bridge in an
* atomic fashion.
*
* If channel specific features are enabled a pointer to the features structure
* can be specified in the features parameter.
*/
enum ast_bridge_channel_state ast_bridge_join(struct ast_bridge *bridge,
struct ast_channel *chan,
struct ast_channel *swap,
struct ast_bridge_features *features,
struct ast_bridge_tech_optimizations *tech_args);
/*! \brief Impart (non-blocking) a channel on a bridge
*
* \param bridge Bridge to impart on
* \param chan Channel to impart
* \param swap Channel to swap out if swapping
* \param features Bridge features structure
* \param allow_hangup Indicates if the bridge thread should manage hanging up of the channel or not.
*
* \retval 0 on success
* \retval -1 on failure
*
* Example usage:
*
* \code
* ast_bridge_impart(bridge, chan, NULL, NULL, 0);
* \endcode
*
* This adds a channel pointed to by the chan pointer to the bridge pointed to by
* the bridge pointer. This function will return immediately and will not wait
* until the channel is no longer part of the bridge.
*
* If this channel will be replacing another channel the other channel can be specified
* in the swap parameter. The other channel will be thrown out of the bridge in an
* atomic fashion.
*
* If channel specific features are enabled a pointer to the features structure
* can be specified in the features parameter.
*/
int ast_bridge_impart(struct ast_bridge *bridge, struct ast_channel *chan, struct ast_channel *swap, struct ast_bridge_features *features, int allow_hangup);
/*! \brief Depart a channel from a bridge
*
* \param bridge Bridge to depart from
* \param chan Channel to depart
*
* \retval 0 on success
* \retval -1 on failure
*
* Example usage:
*
* \code
* ast_bridge_depart(bridge, chan);
* \endcode
*
* This removes the channel pointed to by the chan pointer from the bridge
* pointed to by the bridge pointer and gives control to the calling thread.
* This does not hang up the channel.
*
* \note This API call can only be used on channels that were added to the bridge
* using the ast_bridge_impart API call.
*/
int ast_bridge_depart(struct ast_bridge *bridge, struct ast_channel *chan);
/*! \brief Remove a channel from a bridge
*
* \param bridge Bridge that the channel is to be removed from
* \param chan Channel to remove
*
* \retval 0 on success
* \retval -1 on failure
*
* Example usage:
*
* \code
* ast_bridge_remove(bridge, chan);
* \endcode
*
* This removes the channel pointed to by the chan pointer from the bridge
* pointed to by the bridge pointer and requests that it be hung up. Control
* over the channel will NOT be given to the calling thread.
*
* \note This API call can be used on channels that were added to the bridge
* using both ast_bridge_join and ast_bridge_impart.
*/
int ast_bridge_remove(struct ast_bridge *bridge, struct ast_channel *chan);
/*! \brief Merge two bridges together
*
* \param bridge0 First bridge
* \param bridge1 Second bridge
*
* \retval 0 on success
* \retval -1 on failure
*
* Example usage:
*
* \code
* ast_bridge_merge(bridge0, bridge1);
* \endcode
*
* This merges the bridge pointed to by bridge1 with the bridge pointed to by bridge0.
* In reality all of the channels in bridge1 are simply moved to bridge0.
*
* \note The second bridge specified is not destroyed when this operation is
* completed.
*/
int ast_bridge_merge(struct ast_bridge *bridge0, struct ast_bridge *bridge1);
/*! \brief Suspend a channel temporarily from a bridge
*
* \param bridge Bridge to suspend the channel from
* \param chan Channel to suspend
*
* \retval 0 on success
* \retval -1 on failure
*
* Example usage:
*
* \code
* ast_bridge_suspend(bridge, chan);
* \endcode
*
* This suspends the channel pointed to by chan from the bridge pointed to by bridge temporarily.
* Control of the channel is given to the calling thread. This differs from ast_bridge_depart as
* the channel will not be removed from the bridge.
*
* \note This API call can be used on channels that were added to the bridge
* using both ast_bridge_join and ast_bridge_impart.
*/
int ast_bridge_suspend(struct ast_bridge *bridge, struct ast_channel *chan);
/*! \brief Unsuspend a channel from a bridge
*
* \param bridge Bridge to unsuspend the channel from
* \param chan Channel to unsuspend
*
* \retval 0 on success
* \retval -1 on failure
*
* Example usage:
*
* \code
* ast_bridge_unsuspend(bridge, chan);
* \endcode
*
* This unsuspends the channel pointed to by chan from the bridge pointed to by bridge.
* The bridge will go back to handling the channel once this function returns.
*
* \note You must not mess with the channel once this function returns.
* Doing so may result in bad things happening.
*/
int ast_bridge_unsuspend(struct ast_bridge *bridge, struct ast_channel *chan);
/*! \brief Change the state of a bridged channel
*
* \param bridge_channel Channel to change the state on
* \param new_state The new state to place the channel into
*
* Example usage:
*
* \code
* ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_WAIT);
* \endcode
*
* This places the channel pointed to by bridge_channel into the state
* AST_BRIDGE_CHANNEL_STATE_WAIT.
*
* \note This API call is only meant to be used in feature hook callbacks to
* make sure the channel either hangs up or returns to the bridge.
*/
void ast_bridge_change_state(struct ast_bridge_channel *bridge_channel, enum ast_bridge_channel_state new_state);
/*! \brief Adjust the internal mixing sample rate of a bridge used during
* multimix mode.
*
* \param bridge_channel Channel to change the sample rate on.
* \param sample rate, the sample rate to change to. If a
* value of 0 is passed here, the bridge will be free to pick
* what ever sample rate it chooses.
*
*/
void ast_bridge_set_internal_sample_rate(struct ast_bridge *bridge, unsigned int sample_rate);
/*! \brief Adjust the internal mixing interval of a bridge used during
* multimix mode.
*
* \param bridge_channel Channel to change the sample rate on.
* \param mixing_interval, the sample rate to change to. If 0 is set
* the bridge tech is free to choose any mixing interval it uses by default.
*/
void ast_bridge_set_mixing_interval(struct ast_bridge *bridge, unsigned int mixing_interval);
/*!
* \brief Set a bridge to feed a single video source to all participants.
*/
void ast_bridge_set_single_src_video_mode(struct ast_bridge *bridge, struct ast_channel *video_src_chan);
/*!
* \brief Set the bridge to pick the strongest talker supporting
* video as the single source video feed
*/
void ast_bridge_set_talker_src_video_mode(struct ast_bridge *bridge);
/*!
* \brief Update information about talker energy for talker src video mode.
*/
void ast_bridge_update_talker_src_video_mode(struct ast_bridge *bridge, struct ast_channel *chan, int talker_energy, int is_keyfame);
/*!
* \brief Returns the number of video sources currently active in the bridge
*/
int ast_bridge_number_video_src(struct ast_bridge *bridge);
/*!
* \brief Determine if a channel is a video src for the bridge
*
* \retval 0 Not a current video source of the bridge.
* \retval None 0, is a video source of the bridge, The number
* returned represents the priority this video stream has
* on the bridge where 1 is the highest priority.
*/
int ast_bridge_is_video_src(struct ast_bridge *bridge, struct ast_channel *chan);
/*!
* \brief remove a channel as a source of video for the bridge.
*/
void ast_bridge_remove_video_src(struct ast_bridge *bridge, struct ast_channel *chan);
#if defined(__cplusplus) || defined(c_plusplus)
}
#endif
#endif /* _ASTERISK_BRIDGING_H */
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