draft-ietf-xcon-conference-scenarios-04.txt   draft-ietf-xcon-conference-scenarios-05.txt 
XCON R. Even XCON R. Even
Internet-Draft Polycom Internet-Draft Polycom
Expires: October 27, 2005 N. Ismail Expires: March 10, 2006 N. Ismail
Cisco Systems, Inc. Cisco Systems, Inc.
April 25, 2005 September 6, 2005
Conferencing Scenarios Conferencing Scenarios
draft-ietf-xcon-conference-scenarios-04.txt draft-ietf-xcon-conference-scenarios-05.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 35 skipping to change at page 1, line 35
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on October 27, 2005. This Internet-Draft will expire on March 10, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document describes multimedia conferencing scenarios. It This document describes multimedia conferencing scenarios. It
describes both basic and advanced conferencing scenarios involving describes both basic and advanced conferencing scenarios involving
voice, video, text and interactive text sessions. These conferencing voice, video, text and interactive text sessions. These conferencing
scenarios will help with the definition and evaluation of the scenarios will help with the definition and evaluation of the
protocols being developed in the centralized conferencing XCON protocols being developed in the centralized conferencing XCON
working group. working group.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Basic Conferencing scenarios . . . . . . . . . . . . . . . . 3 2. Basic Conferencing scenarios . . . . . . . . . . . . . . . . . 3
2.1 Ad-hoc conference . . . . . . . . . . . . . . . . . . . . 4 2.1. Ad-hoc conference . . . . . . . . . . . . . . . . . . . . 4
2.2 Extension of a Point to point calls to a multipoint call . 4 2.2. Extension of a Point to point calls to a multipoint
2.3 Reserved conference . . . . . . . . . . . . . . . . . . . 4 call . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Advanced Conferencing scenarios . . . . . . . . . . . . . . 5 2.3. Reserved conference . . . . . . . . . . . . . . . . . . . 4
3.1 Extending a point-to-point call to a multipoint call . . . 5 3. Advanced Conferencing scenarios . . . . . . . . . . . . . . . 5
3.2 Lecture mode conferences . . . . . . . . . . . . . . . . . 5 3.1. Extending a point-to-point call to a multipoint call . . . 5
3.3 Conference with conference aware and unaware 3.2. Lecture mode conferences . . . . . . . . . . . . . . . . . 5
3.3. Conference with conference aware and unaware
participants . . . . . . . . . . . . . . . . . . . . . . . 6 participants . . . . . . . . . . . . . . . . . . . . . . . 6
3.4 A reserved or ad-hoc conference with conference-aware 3.4. A reserved or ad-hoc conference with conference-aware
participants. . . . . . . . . . . . . . . . . . . . . . . 6 participants. . . . . . . . . . . . . . . . . . . . . . . 6
3.5 Advanced conference features . . . . . . . . . . . . . . . 6 3.5. Advanced conference features . . . . . . . . . . . . . . . 6
4. Scenarios for media policy control . . . . . . . . . . . . . 9 4. Scenarios for media policy control . . . . . . . . . . . . . . 9
4.1 Video mixing scenarios . . . . . . . . . . . . . . . . . . 9 4.1. Video mixing scenarios . . . . . . . . . . . . . . . . . . 9
4.2 Typical video conferencing scenario . . . . . . . . . . . 10 4.2. Typical video conferencing scenario . . . . . . . . . . . 10
4.3 Conference Sidebar scenario . . . . . . . . . . . . . . . 10 4.3. Conference Sidebar scenario . . . . . . . . . . . . . . . 11
4.4 Coaching scenario . . . . . . . . . . . . . . . . . . . . 11 4.4. Coaching scenario . . . . . . . . . . . . . . . . . . . . 11
4.5 Presentation and QA session . . . . . . . . . . . . . . . 11 4.5. Presentation and QA session . . . . . . . . . . . . . . . 12
4.6 Presence-enabled ad-hoc conference . . . . . . . . . . . . 12 4.6. Presence-enabled ad-hoc conference . . . . . . . . . . . . 12
4.7 Group chat text conferencing . . . . . . . . . . . . . . . 12 4.7. Group chat text conferencing . . . . . . . . . . . . . . . 12
4.8 Interactive text . . . . . . . . . . . . . . . . . . . . . 12 4.8. Interactive text . . . . . . . . . . . . . . . . . . . . . 13
4.9 Moderated group chat . . . . . . . . . . . . . . . . . . . 13 4.9. Moderated group chat . . . . . . . . . . . . . . . . . . . 13
4.10 Text sidebars . . . . . . . . . . . . . . . . . . . . . 13 4.10. Text sidebars . . . . . . . . . . . . . . . . . . . . . . 13
4.11 Conference announcements . . . . . . . . . . . . . . . . 13 4.11. Conference announcements . . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . 13 5. Security Considerations . . . . . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . 14 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
8. Informative References . . . . . . . . . . . . . . . . . . . 14 8. Informative References . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . . 16 Intellectual Property and Copyright Statements . . . . . . . . . . 16
1. Introduction 1. Introduction
This document describes multimedia conferencing scenarios. The This document describes multimedia conferencing scenarios. The
development of these conferencing scenarios is intended to help with development of these conferencing scenarios is intended to help with
definition and evaluation of the requirements for the centralized definition and evaluation of the requirements for the centralized
conferencing (XCON) working group. Although this document uses some conferencing (XCON) working group. Although this document uses some
definitions and conventions described in the SIP Conferencing definitions and conventions described in the SIP Conferencing
Framework document[1], these scenarios are not SIP-specific. The Framework document[1], these scenarios are not SIP-specific. The
document describes basic and advanced conferencing scenarios. The document describes basic and advanced conferencing scenarios. The
advanced scenarios assume that the user agents support the set of advanced scenarios assume that the user agents support the set of
XCON protocols, identified in the Framework and Data Model for XCON protocols, identified in the Framework and Data Model for
Centralized Conferencing [3], in order to take advantage of the Centralized Conferencing [3], in order to take advantage of the
conference functioality. However, note that many of these features conference functionality. However, note that many of these features
can be implemented today using an IVR or web interface to control the can be implemented today using an IVR or web interface to control the
conferencing application. conferencing application.
The entities comprising the Conferencing System are the conference The entities comprising the Conferencing System are the conference
that is the center point for signaling and the participants. The that is the center point for signaling and the participants. The
participant who initiated the conference is referenced as the participant who initiated the conference is referenced as the
initiating participant. initiating participant.
The scenarios described demonstrate different conferencing services. The scenarios described demonstrate different conferencing services.
These conferencing services can be offered in a multimedia These conferencing services can be offered in a multimedia
skipping to change at page 4, line 5 skipping to change at page 4, line 5
These scenarios enable a conference unaware participant to create, These scenarios enable a conference unaware participant to create,
join and participate in a conference. The participant may use out of join and participate in a conference. The participant may use out of
band signaling to participate in a conference but this is not a band signaling to participate in a conference but this is not a
mandatory requirement. The Conferencing System has all the mandatory requirement. The Conferencing System has all the
functionality it needs in order to supply the service offered to the functionality it needs in order to supply the service offered to the
participants. A typical minimum requirement is that the participant participants. A typical minimum requirement is that the participant
support DTMF tones/signal or provide voice responses to an IVR support DTMF tones/signal or provide voice responses to an IVR
system. system.
2.1 Ad-hoc conference 2.1. Ad-hoc conference
A participant has a service provisioned to him that enables him to A participant has a service provisioned to him that enables him to
start an ad-hoc conference when he calls the Conferencing System. start an ad-hoc conference when he calls the Conferencing System.
When the participant wants to start a conference he calls the When the participant wants to start a conference he calls the
conference service. The participant may be identified by different conference service. The participant may be identified by different
means including request destination, authenticated identity, or an means including request destination, authenticated identity, or an
IVR system using DTMF. The conference is created automatically with IVR system using DTMF. The conference is created automatically with
the predefined functionality. The participant who has such a service the predefined functionality. The participant who has such a service
notifies the other participants how to call the conference via notifies the other participants how to call the conference via
external means such as instant message or email. The participant may external means such as instant message or email. The participant may
have the functionality of a Conferencing System and thus can create have the functionality of a Conferencing System and thus can create
ad-hoc conference using his own user agent functionality. An example ad-hoc conference using his own user agent functionality. An example
of such a conference is an audio conference initiated by one of the of such a conference is an audio conference initiated by one of the
participants who has a conference service that enables him to start a participants who has a conference service that enables him to start a
conference when he calls a specific URI. The conference may be conference when he calls a specific URI. The conference may be
created by the first person calling this URI or it may be created created by the first person calling this URI or it may be created
only after the owner is authenticated using an IVR system. In the only after the owner is authenticated using an IVR system. In the
latter case, the other participants may get an announcement and are latter case, the other participants may get an announcement and are
placed on hold if they call the conference before the owner. placed on hold if they call the conference before the owner.
2.2 Extension of a Point to point calls to a multipoint call 2.2. Extension of a Point to point calls to a multipoint call
This is a basic case. The initiating participant (PA) is in a point This is a basic case. The initiating participant (PA) is in a point
to point call with another participant (PB). PA wants to add a third to point call with another participant (PB). PA wants to add a third
participant (PC) to the call. The initiating participant (PA) cannot participant (PC) to the call. The initiating participant (PA) cannot
provide the Conferencing System functionality on his user agent nor provide the Conferencing System functionality on his user agent nor
can the other participant (PB). PA and PB do not supports call can the other participant (PB). PA and PB do not supports call
transfer. PA has a conferencing service using the methods described transfer. PA has a conferencing service using the methods described
in 2.1. PA conveys the conference information to PB in the point-to- in 2.1. PA conveys the conference information to PB in the point-to-
point call. Both participant disconnect and call the Conferencing point call. Both participant disconnect and call the Conferencing
System. The Conferencing System may support dial out, for example System. The Conferencing System may support dial out, for example
via DTMF, allowing the initiating participant to call the third party via DTMF, allowing the initiating participant to call the third party
through the Conferencing System. through the Conferencing System.
2.3 Reserved conference 2.3. Reserved conference
The reservation for this type of conference is typically done by an The reservation for this type of conference is typically done by an
out of band mechanism and in advance of the actual conference time. out of band mechanism and in advance of the actual conference time.
The conference identification, which may be a URI or a phone number The conference identification, which may be a URI or a phone number
with a pin number, is allocated by the reservation system. It is with a pin number, is allocated by the reservation system. It is
sent to all participants using email, IM, etc. The participants join sent to all participants using email, IM, etc. The participants join
using the conference identification. The conference identification using the conference identification. The conference identification
must be routable enabling the allocation of a conference with free must be routable enabling the allocation of a conference with free
resources at the time when the conference actually run. The resources at the time when the conference actually run. The
Conferencing System can also dial out to the conference participants. Conferencing System can also dial out to the conference participants.
The participants may not be informed that they are in a conference The participants may not be informed that they are in a conference
since their User Agent is not conference aware. The participants may since their User Agent is not conference aware. The participants may
know, via announcement from the Conferenceing System, that they are know, via announcement from the Conferencing System, that they are in
in a conference and who the other participants are. a conference and who the other participants are.
3. Advanced Conferencing scenarios 3. Advanced Conferencing scenarios
These scenarios assume user agents that support at least call These scenarios assume user agents that support at least call
transfer service and a way to communicate information on events from transfer service and a way to communicate information on events from
the Conferencing System to the user agent. The Conferencing System the Conferencing System to the user agent. The Conferencing System
may have the ability to discover the capabilities of the may have the ability to discover the capabilities of the
participants, for example, to identify if they support call transfer. participants, for example, to identify if they support call transfer.
This section specifies in each scenario the dependencies. An This section specifies in each scenario the dependencies. An
advanced conference can be initiated only by an user agent that has advanced conference can be initiated only by an user agent that has
advanced features, but some user agents in the conference may have advanced features, but some user agents in the conference may have
less functionality. less functionality.
3.1 Extending a point-to-point call to a multipoint call 3.1. Extending a point-to-point call to a multipoint call
The initiating participant is in a point-to-point call and wants to The initiating participant is in a point-to-point call and wants to
add a third participant. The initiating participant can start a add a third participant. The initiating participant can start a
multipoint call on a conferencing bridge known to him. The extension multipoint call on a conferencing bridge known to him. The extension
can be without consultation, which means that he moves the point-to- can be without consultation, which means that he moves the point-to-
point call to the Conferencing System and then adds the third party point call to the Conferencing System and then adds the third party
(this can be done in various ways). Alternatively the extension can (this can be done in various ways). Alternatively the extension can
be done with consultation, which means that he puts his current party be done with consultation, which means that he puts his current party
on hold, calls the third party and asks him to join the conference, on hold, calls the third party and asks him to join the conference,
and then transfers all the participants to the Conferencing System. and then transfers all the participants to the Conferencing System.
3.2 Lecture mode conferences 3.2. Lecture mode conferences
This conference scenario enables a conference with a lecturer who This conference scenario enables a conference with a lecturer who
presents a topic and can allow questions. The lecturer needs to know presents a topic and can allow questions. The lecturer needs to know
who the participants are and to be able to give them the right to who the participants are and to be able to give them the right to
speak. The right to speak can be based on floor control or an out of speak. The right to speak can be based on floor control or an out of
band mechanism. band mechanism.
In general, the lecturer is seen/heard by the conference participants In general, the lecturer is seen/heard by the conference participants
and often shares a presentation or application with the other and often shares a presentation or application with the other
participants. participants.
A participant joining this type of conference can get the identity of A participant joining this type of conference can get the identity of
the lecturer and often the identities of the audience participants. the lecturer and often the identities of the audience participants.
This type of conference may have multiple media streams. For This type of conference may have multiple media streams. For
example, if simultaneous language translation is available, a example, if simultaneous language translation is available, a
participant has the option of selecting the appropriate language participant has the option of selecting the appropriate language
audio stream. Multiple video streams could include the speaker's audio stream. Multiple video streams could include the speaker's
face and a whiteboard/demonstration stream. face and a whiteboard/demonstration stream.
3.3 Conference with conference aware and unaware participants 3.3. Conference with conference aware and unaware participants
A conference can include participants that are a mix of conference A conference can include participants that are a mix of conference
aware and unaware participants. Those participants may be conference aware and unaware participants. Those participants may be conference
unaware participants using a proxy function that proxies the advanced unaware participants using a proxy function that proxies the advanced
functionality between the different protocols and the Conferencing functionality between the different protocols and the Conferencing
System. For example, an IVR system or a web page interface can be System. For example, an IVR system or a web page interface can be
used to provide additional functionality. used to provide additional functionality.
3.4 A reserved or ad-hoc conference with conference-aware participants. 3.4. A reserved or ad-hoc conference with conference-aware
participants.
The initiating participant calls the Conferencing System using, for The initiating participant calls the Conferencing System using, for
example, a unique identifier in order to start the conference. The example, a unique identifier in order to start the conference. The
Conferencing System may use some authenticating method to qualify the Conferencing System may use some authenticating method to qualify the
participant. The other participants may call the Conferencing System participant. The other participants may call the Conferencing System
and join the conference. The Conferencing System is able to find the and join the conference. The Conferencing System is able to find the
capabilities of the participants. In case of a reserved conference capabilities of the participants. In case of a reserved conference
the Conferencing System starts the conference at the scheduled time. the Conferencing System starts the conference at the scheduled time.
The participants may join by calling the conference URI or the The participants may join by calling the conference URI or the
Conferencing System may call them. The conference may have privilege Conferencing System may call them. The conference may have privilege
levels associated with a specific conference or participant. The levels associated with a specific conference or participant. The
privileges are for the initiating participant and for a regular privileges are for the initiating participant and for a regular
participant; the initiating participant may delegate privileges to participant; the initiating participant may delegate privileges to
the other participants. The privileges allow functionality as the other participants. The privileges allow functionality as
defined in the next section. defined in the next section.
3.5 Advanced conference features 3.5. Advanced conference features
The following features can be used in all the advanced conferencing The following features can be used in all the advanced conferencing
scenarios. In the examples given in this section, when referring to scenarios. In the examples given in this section, when referring to
a participant that has a functionality it means a participant with a participant that has a functionality it means a participant with
the right privileges. These scenarios may be available in the the right privileges. These scenarios may be available in the
advanced conferencing scenarios and are common in many conferencing advanced conferencing scenarios and are common in many conferencing
applications. This is not a requirement list, rather some examples applications. This is not a requirement list, rather some examples
of how specific functions may be used in a conference. of how specific functions may be used in a conference.
o Add Participants - A participant may add a new participant to the o Add Participants - A participant may add a new participant to the
skipping to change at page 7, line 14 skipping to change at page 7, line 15
phone, discover that the conference has video streams available, phone, discover that the conference has video streams available,
and switch to a video phone. and switch to a video phone.
o Changing Media - During the conference a participant may be able o Changing Media - During the conference a participant may be able
to select different media streams than the one he had when he to select different media streams than the one he had when he
joined the conference. An example is a participant that initially joined the conference. An example is a participant that initially
joined the conference as an audio participant. The participant is joined the conference as an audio participant. The participant is
unable to understand the conversation properly and he learns that unable to understand the conversation properly and he learns that
there is also an interactive text available, he will ask to there is also an interactive text available, he will ask to
receive also the text stream. receive also the text stream.
o Authenticate participants - A participant can authenticate other o Authenticate participants - A participant can authenticate other
participants who want to join the conference. This can be done participants who want to join the conference. This can be done,
implicitly by assigning a password to the conference and letting for example, in a video conferencing session by creating a sidebar
the Conferencing System authenticate the new participants or between the two participants allowing the authenticating
explicitly by directing the authentication requests to the participant to talk with the new participant and verify his
initiating participant who authenticates each participant. identity.
o Authorize participants - A participant can authorize other
participants in order to allow them to join the conference. This
can be done implicitly by assigning a password to the conference
or to each participant and letting the Conferencing System decide
if the new participant is allowed to join. the authorization can
be done explicitly by directing the entered password to the
initiating participant who will authorize each participant. The
conferencing system may use an authentication mechanism to
authenticate the participants.
o Controlling the presentation of media - During the conference the o Controlling the presentation of media - During the conference the
participant may be able to manage whose media is being sent to participant may be able to manage whose media is being sent to
each participant. For example, the participant may be able to each participant. For example, the participant may be able to
decide that he wants to be the speaker and all the rest are decide that he wants to be the speaker and all the rest are
listeners; he may also specify whose media he wants to receive. listeners; he may also specify whose media he wants to receive.
The participant may be able to mute a media stream during the The participant may be able to mute a media stream during the
conference. conference.
o Giving privileges - The participant may want, during the o Giving privileges - The participant may want, during the
conference, to give a privilege to another participant. The conference, to give a privilege to another participant. The
assigning of privileges may be implicit when requested or explicit assigning of privileges may be implicit when requested or explicit
skipping to change at page 7, line 40 skipping to change at page 7, line 50
o Side conferences or sidebars - The participant may want to create o Side conferences or sidebars - The participant may want to create
a side conference that include some of the main conference a side conference that include some of the main conference
participants. When the side conference is done the participants participants. When the side conference is done the participants
return to the main conference. A sidebar may have the same return to the main conference. A sidebar may have the same
functionality as the main conference. There can be several functionality as the main conference. There can be several
sidebars scenarios: sidebars scenarios:
1. Basic sidebar is based on the capabilities of two participants 1. Basic sidebar is based on the capabilities of two participants
to have two calls at the same time, with a point to point call to have two calls at the same time, with a point to point call
in parallel to the main conference. It is user agent in parallel to the main conference. It is user agent
implementation specific whether to automaticly mix both call's implementation specific whether to automatically mix both
streams or allow the participant to manually switch between call's streams or allow the participant to manually switch
them. between them.
2. Conferencing System based sidebar uses the Conferencing System 2. Conferencing System based sidebar uses the Conferencing System
to create the sidebar and compose the relevant sidebar stream to create the sidebar and compose the relevant sidebar stream
mixes. These mixes can include the main conference as an mixes. These mixes can include the main conference as an
incoming stream to the mix. Mechanisms to signal the creation incoming stream to the mix. Mechanisms to signal the creation
of the sidebar, invite participants and control the mixes of the sidebar, invite participants and control the mixes
should be available. should be available.
For example, participants in an audio sidebar may not be heard For example, participants in an audio sidebar may not be heard
by the rest of the conference. However, the main conference by the rest of the conference. However, the main conference
skipping to change at page 8, line 37 skipping to change at page 8, line 47
o Audio-only participants - In a multimedia conference some of the o Audio-only participants - In a multimedia conference some of the
participants who want to join may have no way to send and receive participants who want to join may have no way to send and receive
all the media types. Typically they can send and receive audio. all the media types. Typically they can send and receive audio.
Such participants join the conference as audio-only participants. Such participants join the conference as audio-only participants.
The general case is that participants may send and receive only The general case is that participants may send and receive only
part of the media streams available in the multi media conference. part of the media streams available in the multi media conference.
o Passive participants - In a conference some participants may be o Passive participants - In a conference some participants may be
listeners to all or part of the media streams, but be invisible to listeners to all or part of the media streams, but be invisible to
all the other participants. all the other participants.
o Recorders - A recorder can be added to the conference. A recorder o Recorders - A recorder can be added to the conference. A recorder
can record all streams or a subset of the streams. Recoreders may can record all streams or a subset of the streams. Recorders may
be turned on and off during the conference. Recorders may be used be turned on and off during the conference. Recorders may be used
for "role call" scenario in order to recored a participant name. for "role call" scenario in order to record a participant name.
This name can be annpunced at a later stage automaticly or based This name can be announced at a later stage automatically or based
on a participant request. A recorder is a case of a passive on a participant request. A recorder is a case of a passive
participant. participant.
o Whisper/Private Message - A participant can send a one way message o Whisper/Private Message - A participant can send a one way message
(text, audio, or even some other media) to another participant (text, audio, or even some other media) to another participant
that is immediately rendered. This differs from a sidebar in that that is immediately rendered. This differs from a sidebar in that
it is immediate and creates no long-lived session. it is immediate and creates no long-lived session.
o Human operator - A aprticipant may ask for assistence from a human o Human operator - A participant may ask for assistance from a human
operator during the conference. operator during the conference.
4. Scenarios for media policy control 4. Scenarios for media policy control
During a conference media streams may be controlled by authorized During a conference media streams may be controlled by authorized
participants using either a media control protocol or a third party participants using either a media control protocol or a third party
application. This section describes some typical media control application. This section describes some typical media control
scenarios. The conference can be of any size. Some of the media scenarios. The conference can be of any size. Some of the media
control scenarios are typical to specific conference sizes. As a control scenarios are typical to specific conference sizes. As a
general rule larger conferences scenarios tend to be more centrally general rule larger conferences scenarios tend to be more centrally
managed or structured. managed or structured.
The mixing of media in a conference may start when the conference The mixing of media in a conference may start when the conference
starts or when the initiating participant joins. In the later case, starts or when the initiating participant joins. In the later case,
early aprticipant may be put on hold and get "music on hold". early participant may be put on hold and get "music on hold".
The scenarios apply to audio conferences as well as to multimedia The scenarios apply to audio conferences as well as to multimedia
conferences. There are some specific information about the mixed conferences. There are some specific information about the mixed
video layout and about interactive text discussed below. video layout and about interactive text discussed below.
4.1 Video mixing scenarios 4.1. Video mixing scenarios
For video the participant selects one of a set of pre-defined video For video the participant selects one of a set of pre-defined video
presentations offered by the server. Each video presentation is presentations offered by the server. Each video presentation is
identified by a textual description as well as an image specifying identified by a textual description as well as an image specifying
how the presentation appears on the screen. In this scenario by how the presentation appears on the screen. In this scenario by
choosing a video presentation the participant chooses how many video choosing a video presentation the participant chooses how many video
streams (participants) are viewed at once and the layout of these streams (participants) are viewed at once and the layout of these
video streams on the screen. video streams on the screen.
The contents of each sub-window can be defined by a conference policy The contents of each sub-window can be defined by a conference policy
skipping to change at page 10, line 33 skipping to change at page 10, line 40
- 16 sub-picture view: This presentation shows 16 streams. If the - 16 sub-picture view: This presentation shows 16 streams. If the
streams are to be multiplexed into one image they are arranged in a streams are to be multiplexed into one image they are arranged in a
4x4 style. In this style the aspect ratios are maintained and no 4x4 style. In this style the aspect ratios are maintained and no
cropping or blanking is needed. cropping or blanking is needed.
- 5+1 sub-picture view: This presentation shows 6 streams. If the - 5+1 sub-picture view: This presentation shows 6 streams. If the
streams are to be multiplexed into one image then the pictures are streams are to be multiplexed into one image then the pictures are
laid so that one sub-window occupies 4/9 of the screen while the laid so that one sub-window occupies 4/9 of the screen while the
other five occupy 1/9 of the screen each. other five occupy 1/9 of the screen each.
4.2 Typical video conferencing scenario 4.2. Typical video conferencing scenario
This scenario is known as voice activated video switch. Every This scenario is known as voice activated video switch. Every
participant hears the N loudest participants but he does not hear participant hears the N loudest participants but he does not hear
himself. All the participants see the loudest speaker; the loudest himself. All the participants see the loudest speaker; the loudest
speaker may see the previous loudest speaker. This mode is typical speaker may see the previous loudest speaker. This mode is typical
to small conference. to small conference.
A participant with proper authorization can exclude one or more A participant with proper authorization can exclude one or more
participants from the audio or video mix. An indication might be participants from the audio or video mix. An indication might be
displayed to the affected participants indicating that they are not displayed to the affected participants indicating that they are not
being seen/heard. being seen/heard.
A participant with proper authorization can manipulate the gain level A participant with proper authorization can manipulate the gain level
associated with one or more audio streams in the mix. associated with one or more audio streams in the mix.
4.3 Conference Sidebar scenario 4.3. Conference Sidebar scenario
An authorized participant creates a side bar. The participant An authorized participant creates a side bar. The participant
selects whether the sidebar should include the media from the main selects whether the sidebar should include the media from the main
conference or not and the audio gain level associated with the main conference or not and the audio gain level associated with the main
conference audio. conference audio.
A participant invites participants to the sidebar and upon acceptance A participant invites participants to the sidebar and upon acceptance
they start receiving the sidebar media as specified by the sidebar they start receiving the sidebar media as specified by the sidebar
creator. If the new participant is not a participant of the creator. If the new participant is not a participant of the
conference, but just the sidebar, the participant only receives the conference, but just the sidebar, the participant only receives the
skipping to change at page 11, line 26 skipping to change at page 11, line 34
Sidebar participants with the right authorization can select to hear Sidebar participants with the right authorization can select to hear
or not hear the main conference audio mixed with the sidebar audio or not hear the main conference audio mixed with the sidebar audio
A participant can be a participant to more than one sidebar but can A participant can be a participant to more than one sidebar but can
only actively participate in one. only actively participate in one.
A participant can jump back and forth between the main conference and A participant can jump back and forth between the main conference and
one or more sidebars. one or more sidebars.
4.4 Coaching scenario 4.4. Coaching scenario
This is a call center or a remote training session where there is a This is a call center or a remote training session where there is a
supervisor who can monitor the conference. There are the supervised supervisor who can monitor the conference. There are the supervised
participants that may be the call center operators or the teachers. participants that may be the call center operators or the teachers.
A participant is the conference may be a supervised participant or a A participant in the conference may be a supervised participant or a
"customer". "customer".
The supervisor is a hidden participant and is not part of the The supervisor is a hidden participant and is not part of the
participant roster. participant roster.
The supervised participants might get an announcement/tone indicating The supervised participants might get an announcement/tone indicating
that the supervisor has joined. The other participants do not hear that the supervisor has joined. The other participants do not hear
the announcement. the announcement.
The supervisor listens to / sees the session but can only be heard / The supervisor listens to / sees the session but can only be heard /
seen by the supervised participant. seen by the supervised participant.
The supervisor can become a normal participant, in which case the The supervisor can become a normal participant, in which case the
participants see the supervisor as part of the roster and start participants see the supervisor as part of the roster and start
hearing and seeing him. hearing and seeing him.
4.5 Presentation and QA session 4.5. Presentation and QA session
An example is an earning call scenario in which a group of presenters An example is an earning call scenario in which a group of presenters
deliver material to a group of people. After the presentation is deliver material to a group of people. After the presentation is
finished a QA session is opened. finished a QA session is opened.
The conference is created as a panel and the panel participants are The conference is created as a panel and the panel participants are
identified. Only their streams are mixed. identified. Only their streams are mixed.
After the end of the presentation the session chair changes the After the end of the presentation the session chair changes the
conference type to normal and now streams from all participants may conference type to normal and now streams from all participants may
be mixed. Alternatively a floor control protocol can be used. The be mixed. Alternatively a floor control protocol can be used. The
chair can grant the right to speak by adding the participant, whose chair can grant the right to speak by adding the participant, whose
turn it is to ask a question, to the conference mix. turn it is to ask a question, to the conference mix.
4.6 Presence-enabled ad-hoc conference 4.6. Presence-enabled ad-hoc conference
A presence-enabled ad-hoc conference, sometimes described as "walkie A presence-enabled ad-hoc conference, sometimes described as "walkie
talkie" service, is a scenario in which a participant sends media to talkie" service, is a scenario in which a participant sends media to
the other participants of the conference after receiving a the other participants of the conference after receiving a
confirmation of the other participants' availability. For example, a confirmation of the other participants' availability. For example, a
participant presses a talk button, which checks the presence of the participant presses a talk button, which checks the presence of the
participants to see if they are available for communication. If they participants to see if they are available for communication. If they
are, a confirmation tone is played and the participant can then talk, are, a confirmation tone is played and the participant can then talk,
which results in the media being sent to the other participants in which results in the media being sent to the other participants in
the conference. These types of conferences tend to be long lived, the conference. These types of conferences tend to be long lived,
hence the need for presence to ensure that the other participants are hence the need for presence to ensure that the other participants are
still available. The ad-hoc nature of the conference means that the still available. The ad-hoc nature of the conference means that the
participant list can be changed at any time. Floor control can be participant list can be changed at any time. Floor control can be
used to allow other participants to speak, as the conference is used to allow other participants to speak, as the conference is
usually half-duplex in nature. usually half-duplex in nature.
4.7 Group chat text conferencing 4.7. Group chat text conferencing
Group chat is a common scenario for text messaging in which a Group chat is a common scenario for text messaging in which a
participant joins (or enters) a chat room in which text messages from participant joins (or enters) a chat room in which text messages from
participants are rendered in a single window and attributed to the participants are rendered in a single window and attributed to the
participant that sent the message. Changes in conference membership participant that sent the message. Changes in conference membership
are often announced in the text window itself (e.g. "Alice has just are often announced in the text window itself (e.g. "Alice has just
entered the room. Bob has just departed."). Note that a real-time entered the room. Bob has just departed."). Note that a real-time
transcription/closed captioning service can provide a similar window transcription/closed captioning service can provide a similar window
in which audio media is converted into interactive text. "Nick in which audio media is converted into interactive text. "Nick
names" or aliases are often chosen by participants or assigned by the names" or aliases are often chosen by participants or assigned by the
Conferencing System and used as handles within the room. Conferencing System and used as handles within the room.
4.8 Interactive text 4.8. Interactive text
Interactive text is using RTP to carry text one character at a time Interactive text is using RTP to carry text one character at a time
providing real-time interactivity, as described in RFC2793[2]. The providing real-time interactivity, as described in RFC2793[2]. The
interactive text session may be the main conference itself, or it may interactive text session may be the main conference itself, or it may
be used in conjunction with other media types. Interactive text may be used in conjunction with other media types. Interactive text may
be used to represent the audio in the conference using some be used to represent the audio in the conference using some
translation services. There can be more than one such stream where translation services. There can be more than one such stream where
each text stream is in a different language. These text streams may each text stream is in a different language. These text streams may
be used as subtitles to the audio stream. The translation from to be used as subtitles to the audio stream. The translation from to
text to speech and back is done by transcoders. Those transcoder text to speech and back is done by transcoders. Those transcoder
have similar functionality to transcoders between different audio or have similar functionality to transcoders between different audio or
video algorithms. video algorithms.
The conference participants should be able to select to receive those The conference participants should be able to select to receive those
text streams with the conference audio or without it. text streams with the conference audio or without it.
4.9 Moderated group chat 4.9. Moderated group chat
A moderated group chat scenario for text messaging is similar to A moderated group chat scenario for text messaging is similar to
group chat but with all text messages sent to the group being group chat but with all text messages sent to the group being
filtered/approved by a moderator. Note that the moderator can be a filtered/approved by a moderator. Note that the moderator can be a
human or an application. The moderator also often has the ability to human or an application. The moderator also often has the ability to
remove participants and provide feedback on their submissions (e.g. remove participants and provide feedback on their submissions (e.g.
provide warnings before removal). provide warnings before removal).
4.10 Text sidebars 4.10. Text sidebars
Interactive text or instant messaging sidebars are perhaps the most Interactive text or instant messaging sidebars are perhaps the most
common sidebars in conferences today. Often the text sessions are common sidebars in conferences today. Often the text sessions are
separate from the conference. However, there are some advantages to separate from the conference. However, there are some advantages to
having text sessions be a sidebar and as a result a part of the main having text sessions be a sidebar and as a result a part of the main
conference. For example, a conference which is providing anonymity/ conference. For example, a conference which is providing anonymity/
aliases to participants can also provide anonymous/alias sidebars. A aliases to participants can also provide anonymous/alias sidebars. A
text sidebar can also benefit from other security/logging/recording text sidebar can also benefit from other security/logging/recording
services provided by the Conferencing System. services provided by the Conferencing System.
Another use of a text sidebar is a text-only conversation/discussion Another use of a text sidebar is a text-only conversation/discussion
between two or more conference participants who at the same time are between two or more conference participants who at the same time are
following the main conference. following the main conference.
4.11 Conference announcements 4.11. Conference announcements
The conference moderator may be able to play announcements to all the The conference moderator may be able to play announcements to all the
conference participants. The announcement may be pre-recorded or conference participants. The announcement may be pre-recorded or
composed by the moderator before sending them. The announcements may composed by the moderator before sending them. The announcements may
be text, audio or audio visual. An example is a conference with be text, audio or audio visual. An example is a conference with
several audio break-out sessions going on. At some point in the several audio break-out sessions going on. At some point in the
time, the moderator wants to record an audio message like "in 5 time, the moderator wants to record an audio message like "in 5
minutes, everyone please come back to the main meeting" and then play minutes, everyone please come back to the main meeting" and then play
that message to all of the breakout sessions. that message to all of the breakout sessions.
 End of changes. 

This html diff was produced by rfcdiff 1.25, available from http://www.levkowetz.com/ietf/tools/rfcdiff/