SIPREC P. Kyzivat
Internet-Draft M. Yan
Intended status: Informational Huawei
Expires: November 17, 2013 May 16, 2013
Web Conference Recording Use Case
draft-kyzivat-siprec-webconf-use-case-00
Abstract
The current work of SIPREC will soon finish. As its charter defined,
SIPREC has covered industries like financial trading floors, contact
center and emergency service bureaus. But when talking about
products or solutions like data or web conferencing, SIPREC is
insufficient to record all aspects of calls with different
interactive media channels. This draft tries to show a use case for
web conference recording and show how it can work well under SIPREC
mechanism.
Requirements Language
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].
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
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 17, 2013.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Web Conference . . . . . . . . . . . . . . . . . . . . . 2
1.2. Multimedia Recording and Layout . . . . . . . . . . . . . 3
1.3. Recording Session . . . . . . . . . . . . . . . . . . . . 4
2. Requirements for Web Conference Recording . . . . . . . . . . 4
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. Informative References . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
1.1. Web Conference
In general, a basic video conference has participants with video
channels and audio channels with DTMF ability. A more complex
multimedia conference would have text, interactive text and
presentation graphics [RFC4597]. A web conference, known as a
webinar or, for interactive conferences, online workshop, refers to a
service that allows conferencing events to be shared with remote
locations. It has needs for recording as strong as those for
financial trading floors and contact centers. The host and
participants, and even nonparticipants, would like to play back the
conference recording for further purposes, like editing a conference
summary, reviewing conference outlines or replaying the whole
conference process. The recording should reconstruct, as much as
possible, the web conference including all media types not only audio
/video but also IM, data sharing and even presentation information
like layout. Such an exhaustive reconstruction could give audiences
more information and a better experience.
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1.2. Multimedia Recording and Layout
There is one use case covering the recording of a multi-channel and
multimedia session in the existing use case document [RFC6341].
Aside from audio, video and IM, it does not mention other interaction
modalities. The limitations of the multi-channel typies leads to
poor support for web conference recording. A web conference has
various media types, including audio, video, IM, data sharing(desktop
/document/application/whiteboard) and polling. SIPREC is already
mostly capable of recording any sort of RTP media sessions, including
voice, DTMF, video, and text [RFC6341] with SDP negotiation
[I-D.ietf-siprec-protocol]. But it is not evident how to support the
remaining media.
The media streams like desktop/document/application/whiteboard
sharing could be managed as still images (snapshots with increments)
or as dynamic streams (video streams) to cover details like
annotating, direct editing or page turning. The still image could be
also treated as the payload in rtp stream. For instance, one
snapshot bitmap from desktop could be inserted as an I frame of a
recording RTP stream that uses the SIP recording mechanism. So those
streams could be recorded via RTP stream.
In many cases the conference server controls the layout views of
media data, especially for video streams, on the screens of the
participants in the conference. In addition, participants or
conference host might change the layout for their preferred pane
assignment. When participants act the SRC and make the recording for
themselves, they might use their own layout for special purpose, like
put the IM session into the larger pane temporarily for writing some
key details into a summary, or permanently close the less significant
participants' video stream outputs to earn a larger pane for slide
sharing of a online class training . It would be useful to have
information about how that was done for each participant, and the
recommended way of doing it for after-the-fact viewers, as part of
the recording, so that the playbacks can do a proper rendering.
The layout of a web conference is used to decide how to organize the
multi-windows, when playing back the recording, considered as a set
of predefined video presentations offered by the server [RFC4597].
Take video recording as an example. There are some key crucial
factors, like the desired recording resolution or largest active
speaker, that affect SRC/SRS decisions about how many video streams
(participants) are viewed at once and the layout of these video
streams on the screen [RFC4597]. And the data sharing's content
[RFC4796] could also effect the layout in a web conference when
presenting with video channels together. These layout metadata could
be defined by SRC or by config/default setting on SRS. If it is
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defined by SRC, the metadata could be delivered to SRS at the
beginning of the RS, and updated with the increments later.
Below is a simple example for the layout of a web conference. A is
for participant list, B is for IM, while C is for desktop sharing.
And D1, D2, D3 are to support different video windows from each
participant.
+----------------+----------------------------+
| | |
| A | |
| | C |
+----------------+ |
| | |
| B +--------+---------+---------+
| | D1 | D2 | D3 |
+----------------+--------+---------+---------+
Figure 1: The Layout of A Web Conference
1.3. Recording Session
One way for a conference focus to record a conference is introduced
in [I-D.ietf-siprec-architecture]. This defines how the conference
focus works as an SRC to deliver RTP streams and associate recording
metadata to SRS. It may choose the recording RTP stream type,
separated or mixed. There are more details about how to use SDP, RTP
for recording by participant or by media type in
[I-D.ietf-siprec-protocol]. The focus may setup different recording
sessions for different media streams recorded separately, or one
recording session for a mixed media stream created by the SRC, or
even multiplexing different media streams in a single RTP recording
session[I-D.ietf-siprec-protocol].
But more is needed to support other media streams in a web
conference. There is need for a new type of "media stream" for data
sharing, distinct from the main video streams, with different m-lines
or metadata. Other new "media stream" types are needed for delivery
of SIP based IM message and polling message. There is also need of a
mechanism for the SRC to bound the number of media streams to be
recorded, especially when the participant number in a conference is
large.
Recording XMPP based IM in CS is out of the scope for this proposal.
It may be added later.
2. Requirements for Web Conference Recording
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1. The mechanism MUST support MSRP media stream recording.
2. The mechanism MUST support data sharing recording, data sharing
including desktop/document/application/whiteboard.
3. The mechanism MUST support polling recording.
4. The mechanism MUST support record the layout of web conference,
if SRC offer the details. The layout details can be adjusted by
demand.
3. IANA Considerations
This document contains no IANA considerations.
4. Security Considerations
Not explicitly covered in this version.
5. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC4597] Even, R. and N. Ismail, "Conferencing Scenarios", RFC
4597, August 2006.
[RFC4796] Hautakorpi, J. and G. Camarillo, "The Session Description
Protocol (SDP) Content Attribute", RFC 4796, February
2007.
[RFC6341] Rehor, K., Portman, L., Hutton, A., and R. Jain, "Use
Cases and Requirements for SIP-Based Media Recording
(SIPREC)", RFC 6341, August 2011.
[I-D.ietf-siprec-architecture]
Hutton, A., Portman, L., Jain, R., and K. Rehor, "An
Architecture for Media Recording using the Session
Initiation Protocol", draft-ietf-siprec-architecture-07
(work in progress), November 2012.
[I-D.ietf-siprec-protocol]
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Portman, L., Lum, H., Eckel, C., Johnston, A., and A.
Hutton, "Session Recording Protocol", draft-ietf-siprec-
protocol-09 (work in progress), December 2012.
[I-D.ietf-siprec-metadata]
R, R., Ravindran, P., and P. Kyzivat, "Session Initiation
Protocol (SIP) Recording Metadata", draft-ietf-siprec-
metadata-11 (work in progress), January 2013.
Authors' Addresses
Paul H. Kyzivat
Huawei
Email: pkyzivat@alum.mit.edu
Michael Yan
Huawei
Email: michael.yan@huawei.com
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