Edited & Last Updated 7/08/2001 by
jow
Streaming and Conferencing Scenarios
This work is intended to supplement work underway by the Internet2 VidMid
Working Group, particularly that
of Egon Verharen at SURFNet.
Draft streaming video application scenarios arising in a VidMid
WG teleconference call on 6/25/01 are presented below for review, comment and incorporation, with or without revision or attribution, into any other
work. These scenarios reflect deployment and usage patterns and plans seen
among the known-to-me IP-video early adopters in the Western New York
region. These scenarios are only for observed patterns and plans not seen
in other scenario descriptions.
Please direct any and all comments to me, Jim Whitlock, at whitlock@buffalo.edu.
While not really wishing to provoke the detailed dialectic
debate I so love, nonetheless, I would like to hear any opinions about my having
presumed implicit permission to re-post what is sent on the VidMid list here, on
a Web site in gestation for my regional group. I did it both for my own
personal reflection, benefit and convenience, and to include others locally as
appropriate to inform as well as for advice and consultation. I have
already, for example, re-posted several items in Reference
Library sections for such
purposes.
I could ask for permission on each item or from each author for
all their offerings but at some point cost exceeds benefit. If freely re-postable,
I think VidMid material will benefit all of us as more folks become aware of
issues and as more of them input their own unique perspectives.
Regardless, I think it could be a simple group consciousness issue.
Comments?
Streams and VOD as Successively Reduced-Cost Participatory
Modes 
for Real-time Interactive Events
Description: People and organizations often
perceive streaming video and video-on-demand (VOD), per se, as being as much
alternative modes of participation in live events also supported by real-time
videoconferencing as being separate communications modes of their own. One
can argue that in some ways streaming video communication is actually a
superset of real-time videoconferencing with 1) higher quality audio and video,
2) archival recording (and playback) capability, 3) generally no-cost or
marginal-cost ubiquitously available viewers that do not require hardware
additions, 4) inherent support for parallel streams of overheads or other
supplemental visual channels, 5) generally higher latency, and 6) generally
higher bandwidth quality and quality requirements.
In this view, an event worth supporting with videoconferencing
access, is also routinely streamed live and captured with the highest capture quality
possible. The live streams make it possible for people anywhere, who will
not have real-time H.323 equipped systems available to them, to participate
actively with an audio and video feed of the event and with a telephone or
text based back-channel for their interaction. The VOD files made
available immediately after the event make it possible for remote participants
to refresh aspects of the event from which they were distracted or to review
material for more intense study. Streams and VOD, in this view, are merely
functional variants of general IP-video based remote participation support for an
event.
Example: As a specific example, The WNY High
Performance Networked Video Initiative, supports an Extended Grand Rounds
project on public-access facilities as an on-going living-laboratory. The events are
serious trials in the IP-video application space that will fortify and shape
grant applications for deployment research proposals. Most of the primary sites in
a funded traffic injury research project at the Erie County Medical Center had
been sharing research related Grand Rounds by dial-up
videoconferencing. As we start to trial and explore migrating the Grand
Rounds from dial-up to IP-video technologies, we've included streams and VOD as
an integral part of the effort.
Once primary sites are connected on-line via H.320 ISDN, an MCU cascade is
established to integrate the IP-video domain. A special head-end H.323
system (in this case one based on a Zydacron Z350 CODEC), with the capability to
provide an output of both the local screen video (what you would normally see
with a single-display H.323 system) and a mix of the local and remote audio, is
then connected by dialing a connection to the H.323 MCU. It's special logging output is
always connected through distribution amplifiers to both IP/TV and Windows Media
Player (WMP) stream encoders and servers. The former provides high quality,
high bandwidth multicast real-time streams of the live event for those with
appropriate connectivity but without convenient or immediate access to H.323
facilities. The latter provide the same general functional benefits at
lower quality and bandwidth-demand levels for dial up users. The only
limitation imposed by participating via live streams is that a participant's own
video will not be available to other participants. After-the-fact
partcipants using VOD files will obviously not be able to interact in real-time
with the event hosts or source. In all other regards, however, stream participants enjoy
equal if not higher quality remote event participation.
Interaction methods will vary across the spectrum of
participation modes. Real-time participants will generally have little
need of supplemental communications channels for interaction other than those
that are central to the real-time event like FAX, application sharing, streamed
overheads, or follow-me browsing. All of the stream participants will have
access to telephone (including IP telephony) and text based channels (email,
chat, etc.) to the appropriate real-time site(s) for questions and interaction
in real-time. In addition, IP/TV and WMP VOD files will be indexed and
made available for on-demand viewing immediately after the event completes with
email and conventional follow-up possible. As a bandwidth conserving
strategy, VOD file presentation can be delayed until the completion of a period (1-2 days,
for example) of scheduled multicast rebroadcasts (say, eight
times per day/night) to attempt to satisfy short-term review demand with lower
impact multicast, rather than unicast, network transport.
Needed Components: For the primary interactive
sites, H.323 (or H.320) endpoints and appropriate network connectivity are needed.
For people participating via stream modes, needs include a PC with a stream
viewer client, appropriate Internet connectivity and whatever back-channels may
be desired or required.
Streaming Video
as a Security Monitoring Tool
Description: With the ever increasing ubiquity of
IP network connections, declining component costs, and the increasingly
appliance-like nature of components, both H.323 and streaming video afford
excellent tools for security monitoring applications. As in other
scenarios and as discussed elsewhere, streaming video technologies here should be seen as a simple
functional variant of generalized IP-video connection technologies that include
H.323 videoconferencing. In fact, appliances that can effectively do both
are starting to emerge. The VCON ViGO Professional is an example of one
that can be used alternatively as a H.323 endpoint or as an H.261 multicast
stream source, and other models from other manufacturers can do both
simultaneously.
Example: VCON
ViGO/PC pairs could be deployed at
any number of locations where centralized monitoring by security staff is
warranted. In some locations, the units would be deployed as multicast
stream sources. Where back channels are needed at stream-source endpoints,
at doorway entrances, for example, a telephone (IP or analog) or intercom could
be used. Where a real-time visual back-channel may be required, in the
president's office or for a two-person visually and mutually authenticated
access context, for example, the units could be deployed as H.323 endpoints
provided the lower quality video and audio are acceptable. In still other
cases, the choices of endpoint operating mode (steam versus interactive) might
be determined by bandwidth constraints,
network topology, time-to-switch, or by ease of incorporation into multipoint
automated logging systems.
Logging, whether time-lapse or continuous, whether all-points
simultaneously or selected points serially or simultaneously, could now be
accomplished either with traditional off-line audio and video recording
technologies or with on-line VOD production and capture capabilities. PC
controled switching matrices, switchers and titlers could easily be included and
integrated to the extent desired. Various scenarios
for integrating stream capture, live stream re-broadcast and VOD file
presentation have been addressed above and
elsewhere.
Above and beyond employing an increasingly ubiquitous connection
and transport fabric, live streams benefit IP-video security applications by permitting multipoint analysis of and consultation on
security events at low marginal cost, both indirect (e.g. bandwidth) and direct,
and their captured VOD files provide recorded
evidence for subsequent review and legal or administrative action.
Needed Components: [usual IP-video stuff, depending
on deployment modes]
Streaming
Video as an Improved Remote Site Content-Origination Source Feed
for Centralized Support of Real-Time IP-video Supported Events
[On using MPEG-1 or MPEG-2 low-latency bi-directional streaming
appliances at primary content origination source sites for real-time events to
reduce the complexity of imported equipment at that site and to improve the
audio/video quality of the feed to the central support location providing H.323
and stream support facilities.] Description: In many
cases, we believe that low-cost low-latency streaming video appliances may
afford reduced costs and improved quality for IP-video support of real-time
events in remote locations where centralized IP-video support is being
provided. Such an appliance would replace the H.323 endpoint at the
primary content origination site. Cost reductions may arise from reduced
support complexity with fewer peripheral issues like those related to H.323
Gatekeepers and institutional Firewalls. Quality improvements arise from
the audio and video compression algorithms (MPEG-1 and MPEG-2, for example) used
by steaming appliance systems. Example: In any
real-time H.323 context, any H.323 link to a remote site can be replaced with
one based upon a pair of low-latency streaming appliances, like VBricks, to
deliver the primary event source content back to a complex real-time and
streaming support facility located anywhere on the Internet. In the
extended Grand Rounds Scenario above, for
example, the featured lecture/presentation could be by a physician on-site at
some disaster relief center halfway around the world. The only component
necessary to support the presenter beyond a local camera/microphone setup would be a
streaming appliance like a VBrick. The quality of the audio and video
feed for the other event participants will be improved by the streaming
compression algorithms and bandwidth while the local operational setup and
support costs will be reduced by absence of an H.323 endpoint and its own
attendant technical support issues. In all other regards, possibly
excepting the latency contributions of the stream support appliances and their
integration methods, other participants would enjoy equal or improved remote
participation than if the event had been supported with an H.323 link to the
primary event source content origination site. Needed
Components: [usual IP-video stuff, depending on deployment modes]
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