Introduction

App_Vonference is a channel-independent video conference application.
It features efficient audio mixing algorithms as well as video selection
support based on VAD, DTMF or CLI (it is a fork of the Konference project).


Design goals

App_vonference has several design goals which are different than Meetme:

    * It does not require a zap channel for timing.
    * It is very efficient when used with channels which support DTX (silence
	detection/discontinuous transmission).

    * It can do VAD on channels which do not support DTX (although this 
	is more expensive than just mixing them, but less expensive then
	encoding; therefore it might still be a win). 
    * It presents messages on the Monitor interface for determine which 
	speakers are active. 

Mixing design

    * Minimize encoding/decoding, minimize mixing.
    * Minimize generational loss from trancoding.
    * Usual cases are handled very efficiently:
          o One speaker: That speaker's frame is sent directly to each 
		participant which uses the same codec. It is trancoded 
		_once_ for each additional codec type used by participants.
          o Two speakers: Each speaker gets the other speaker's frames.  
		The two speaker's frames are decoded and mixed, and then 
		encoded _once_ for each codec type used by participants. 

Video features

    * Video passthrough: video from selected member is passed to every
        member of the conference.
    * Multiple ways to select video
        - VAD
	- DTMF from conference members
	- CLI 
    * Ability to set default video sources and to lock/unlock video sources.


License

Naturally, app_vonference is GPL. The GIT repository also includes parts of
libspeex, which is distributed under a BSD-style license. See LICENSE for more
details.


Getting app_vonference

app_vonference is available via GIT from github:

    * https://github.com/voximal/asteisk-vonference


Compiling app_vonference

    * Checkout sources
    * Modify Makefile to point to your Asterisk include directory
    * make
    * sudo make install 


Using app_vonference

There is no configuration file. Conferences are created on-the-fly.

Dialplan syntax:

Vonference(NAME,FLAGS[,MAXUSERS][,TYPE][,SPY][,VADSTART][,VADCONTINUE][,VIDEOSTART][,VIDEOSTOP])

* NAME: whatever you want to identify the conference
* FLAGS: dialplan flags, see Flags.txt for a comprehensive list

* MAXUSERS: limit conference participants to max_users
* TYPE: conference type identifier
* SPY: channel name to spy

* VADSTART:  "probability" to use to detect start of speech.
* VADCONTINUE: "probability" to use to detect continuation of speech. 
* VIDEOSTART: length of speech before assuming that a member is speaking 
* VIDEOSTOP: length of silence before assuming that a member has stopped speaking


CLI Commands

Please look at CLI.txt for a comprehensive list of CLI commands and parameters.


Manager Events

app_vonference generates several detailed manager events so that applications
interfacing with the manager API can monitor conferences:

	* ConferenceJoin: join conference
	* ConferenceLeave: leave conference

	* ConferenceDTMF: dtmf received
	* ConferenceState: speaking state changed
	* ConferenceSoundComplete: sound completed

	* ConferenceMemberMute: mute member
	* ConferenceMute: mute conference
	* ConferenceMemberUnmute: unmute member
	* ConferenceUnmute: unmute conference

	* ConferenceCameraDisabled: camera disabled
	* ConferenceCameraEnabled: camera enabled
	* ConferenceStopVideoTransmit: stop video
	* ConferenceStartVideoTransmit: start video
	* ConferenceUnlock: unlock conference video
	* ConferenceLock: lock conference video
	* ConferenceVideoBroadcastOff: video broadcast off
	* ConferenceVideoBroadcastOn: video broadcast on
	* ConferenceVideoMute: mute video
	* ConferenceVideoUnmute: unmute video
	* ConferenceDefault: set video default
	* ConferenceVideoSwitch: video switched



Benchmarking

It would be nice to have solid benchmarks to present, but a good size 
machine should be able to handle many callers when either (a) they are 
using DTX, or (b) they are listen-only.  It's used often with hundreds of
simultaneous callers.


---