Internet DRAFT - draft-wenger-clue-definitions
draft-wenger-clue-definitions
CLUE WG S. Wenger
Internet-Draft Vidyo, Inc.
Intended status: Informational October 31, 2011
Expires: May 3, 2012
CLUE Definitions
draft-wenger-clue-definitions-02.txt
Abstract
This document collects terminology and definitions to be used
consistently among documents produced in the CLUE working group.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on May 3, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
7. Informative References . . . . . . . . . . . . . . . . . . . . 7
Appendix A. Draft History . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
This document collects terminology and definitions to be used
consistently among documents produced in the CLUE working group. The
draft is intended to be a living document, to be updated as the
working group discussions progress. It is not intended for
publication as an RFC; instead, it is expected that definitions and
terminology defined herein are going to be replicated in other CLUE
documents.
All defined terms herein are captitalized. It is recommended that
authors of other CLUE document follow this conventions when using
definitions from this document.
It should be understood that the definitions herein are not to be
interpreted as antedating design decisions to be made later. It's
entierly reasonable that design choices conflicting with definitions
in this draft may become necessary. In such cases, CLUE document
authors can either request the definition be updated, or can simply
avoid the use of a definition of this document. However, an author
should never use a capitzalied definition as set forth herein with a
different meaning in a different CLUE document.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Definitions
Audio Capture: Media Capture for audio. Denoted as ACn.
Audio Mixing: refers to the accumulation of scaled audio signals
to produce a single audio stream. See RTP Topologies,
[RFC5117].
Camera-Left and Right: For media captures, camera-left and
camera-right are from the point of view of a person observing
the rendered media. They are the opposite of stage-left and
stage-right.
Capture Device: A device that converts audio and video input
into an electrical signal, in most cases to be fed into a media
encoder. Cameras, microphones, and keyboards are examples for
capture devices.
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Capture Scene: the scene that is captured by a collection of
Capture Devices. A Capture Scene may be represented by more
than one type of Media. A Capture Scene may include more than
one Media Capture of the same type. An example of a Capture
Scene is the video image of a group of people seated next to
each other, along with the sound of their voices, which could be
represented by some number of VCs and ACs. A middle box may
also express Capture Scenes that it constructs from Media
streams it receives.
Capture Set: includes Media Captures that all represent some
aspect of the same Capture Scene. The items (rows) in a Capture
Set represent different alternatives for representing the same
Capture Scene.
Conference: used as defined in [RFC4353], A Framework for
Conferencing within the Session Initiation Protocol (SIP).
Encoding Group: Encoding group: A set of encoding parameters
representing a device's complete encoding capabilities or a
subdivision of them. Media stream providers formed of multiple
physical units, in each of which resides some encoding
capability, would typically advertise themselves to the remote
media stream consumer as being formed multiple encoding groups.
Within each encoding group, multiple potential actual encodings
are possible, with the sum of those encodings' characteristics
constrained to being less than or equal to the group-wide
constraints.
Endpoint: The logical point of final termination through
receiving, decoding and rendering, and/or initiation through
capturing, encoding, and sending of media streams. An endpoint
consists of one or more physical devices which source and sink
media streams, and exactly one [RFC4353] Participant (which, in
turn, includes exactly one SIP User Agent). In contrast to an
endpoint, an MCU may also send and receive media streams, but it
is not the initiator nor the final terminator in the sense that
Media is Captured or Rendered. Endpoints can be anything from
multiscreen/multicamera rooms to handheld devices.
Endpoint Characteristics: include placement of Capture and
Rendering Devices, capture/render angle, resolution of cameras
and screens, spatial location and mixing parameters of
microphones. Endpoint characteristics are not specific to
individual media streams sent by the endpoint.
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Front: the portion of the room closest to the cameras. In going
towards back you move away from the cameras.
Individual Encode: A variable with a set of attributes that
describes the maximum values of a single audio or video capture
encoding. The attributes include: maximum bandwidth- and for
video maximum macroblocks, maximum width, maximum height,
maximum frame rate. [Edt. These are based on H.264.]
Layout: How rendered media streams are spatially arranged with
respect to each other on a single screen/mono audio telepresence
endpoint, and how rendered media streams are arranged with
respect to each other on a multiple screen/loudspeaker
telepresence endpoint. Note that audio as well as video is
encompassed by the term layout--in other words, included is the
placement of audio streams on loudspeakers as well as video
streams on video screens. Edit. note: this is on the RENDERER
side.
Left: to be interpreted in the context of the description where
the word occurs." Edt. note: there has been a lot of mailing
list discussions about "left" and "right", and we seem not to be
able to arrive at a common understanding.
Local: Sender and/or receiver physically co-located ("local",
"in the same room") in the context of the discussion.
MCU: Multipoint Control Unit (MCU) - a device that connects two
or more endpoints together into one single multimedia conference
[RFC5117]. An MCU includes an [RFC4353] Mixer. Edt. Note:
RFC4353 is tardy in requireing that media from the mixer be sent
to EACH participant. I think we have practical use cases where
this is not the case. But the bug (if it is one) is in 4353 and
not herein.
Media: Any data that, after suitable encoding, can be conveyed
over RTP, including audio, video or timed text. Edt. note: does
Media include far end camera control (which can be conveyed over
RTP)?
Media Capture: a source of Media, such as from one or more
Capture Devices. A Media Capture (MC) may be the source of one
or more Media streams. A Media Capture may also be constructed
from other Media streams. A middle box can express Media
Captures that it constructs from Media streams it receives.
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Media Consumer: an Endpoint or middle box that receives Media
streams
Media Provider: an Endpoint or middle box that sends Media
streams
Model: a set of assumptions a telepresence system of a given
vendor adheres to and expects the remote telepresence system(s)
also to adhere to.
Participant: to be interpreted as defined in RFC 4353
Remote: Sender and/or receiver on the other side of the
communication channel (depending on context); not Local. A
remote can be an Endpoint or an MCU.
Render: the process of generating a representation from a media,
such as displayed motion video or sound emitted from
loudspeakers.
Rendering Device: A device that converts an electrical signal -
in most cases stemming from a media decoder - to audible and
visual signals. Screens and loudspeakers are examples for
rendering devices.
Right: to be interpreted in the context of the description where
the word occurs."/>
Simultaneous Transmission Set: a set of media captures that can
be transmitted simultaneously from a Media Provider.
Source selection policies: rules for determining which media
source(s) to play or show.
Spatial Relation: The arrangement in space of two objects, in
contrast to relation in time or other relationships. See also
Left and Right.
RTP stream as in [RFC3550].
Stream Characteristics: include media stream attributes commonly
used in non-CLUE SIP/SDP environments (such as: media codec, bit
rate, resolution, profile/level etc.) as well as CLUE specific
attributes (which could include for example and depending on the
solution found: the I-D or spatial location of a capture device
a stream originates from).
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Telepresence: an environment that gives non co-located users or
user groups a feeling of (co-located) presence - the feeling
that a Local user is in the same room with other Local users and
the Remote parties. The inclusion of Remote parties is achieved
through multimedia communication including at least audio and
video signals of high fidelity.
"Telepresence Extensions": The protocol extensions beyond SIP
adn its extensions defined as of July 2011, specified by RFC
XXXX. (XXX to be replaced by the RFC editor with any documents
developed by the CLUE WG that contain normative content, such as
architecture, protocol specification, and whatnot.)
Video Capture: Media Capture for video. Denoted as VCn.
Video composite: A single image that is formed from combining
visual elements from separate sources.
4. Acknowledgements
Most of this stuff is copied from the CLUE requirements and framework
draft. Go there to look at dignitaries.
5. IANA Considerations
None
6. Security Considerations
None
7. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5117] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117,
January 2008.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC4353] Rosenberg, J., "A Framework for Conferencing with the
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Session Initiation Protocol (SIP)", RFC 4353,
February 2006.
[StageDirection(Wikipadia)]
Wikipedia, "Blocking (stage), available from http://
en.wikipedia.org/wiki/Stage_direction#Stage_directions",
May 2011, <http://en.wikipedia.org/wiki/
Stage_direction#Stage_directions>.
Appendix A. Draft History
01: removed "stage direction" in "left" "right". Replaced with "to
be interpreted in context".
clarified "local" to mean "in the same room" per J. Polk email
6/14/11
Consistently refer to "loudspeaker" per Christer's email 6/13/11
Added "keyboard" to listed caputure devices per Christer's email
6/13/11
Rendering device: changed "optical" to "visual". Hope Christer finds
this OK. Per Christer's email 6/13/11
Note: the other changes proposed by Christer in his 6/13 email appear
to change more than just words but semantics. Not included here as
such semantic changes are best handled in the requirement and other
docs.
Edt. Note: there have been lengthily discussions about the term
"Participant". One camp wanted the word to refer to human users of
telepresence equipment so to use intuitive language, the other (as
this document) suggests to use the word in the RFC
Participant defined as per RFC 4353. I think this is what we arrived
at on the mailing list, right?
Added "Telepresence Extensions" per long "solutions" thread.
00: Initial version; mostly copy-past from requirements-02.
Removed "session". Editors are advised to be specific about SIP,
RTP, or whatever else sessions.
Made clear that Layout refers to rendering, not capturing.
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added Left, Right, in stage direction, w/ Wikipedia reference
Author's Address
Stephan Wenger
Vidyo, Inc.
433 Hackensack Ave., 7th Floor
Hackensack, NJ 07601
USA
Email: stewe@stewe.org
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