Transcript Recommending a Strategy - NUS Centre for Instructional

Streaming Videoconferences
Soh Hock Heng
National University of Singapore
Doug Pearson
Internet2 Commons Site Coordinator Training
December 3, 2003
National University of Singapore
Streaming
 Streaming is the one-way delivery of digital
content from a streaming server to a streaming
client in a continuous, paced, and controlled
flow.
 Streaming alleviates the need to download an
entire media clip as a file.
• Live events don’t exist as a file yet!
• Allows playing to start before download is completed
• Protects copyright
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Streaming a
Videoconference
 Streaming a videoconference makes it
possible for any number of people to
view a conference – either live or
recorded for on-demand access.
 Viewers use desktop computers with
standard media players such as Real,
Windows Media, or QuickTime.
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What Kinds of Things
Can You Do?
 Key individuals participate interactively by
videoconference; a larger audience views
the live stream.
 Save the proceedings of a meeting.
 Make a class or lecture available ondemand for student review.
 In fact, maybe all you want to do is stream
an event – you don’t need to
videoconference. You have a
videoconferencing appliance in the room,
and…
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Interactive for Live
Events
 Streaming is a one-way delivery of media.
 Participants in a live, streaming event can
participate interactively by:
• E-mail to a conference facilitator
• On-line chat
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Four Methods to Stream
a Videoconference
All-in-one box solutions
Combination of videoconferencing
terminal and standard streaming
encoder
Videoconferencing appliances with
built-in H.26x/G.7xx multicast
streaming
Application service providers
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All-In-One Box
 As either an
• H.323 terminal and a streaming server, or
• H.323 MCU and streaming server.
 These devices
• Take the H.26x video and G.7xx audio out of an
H.323 envelope and stuff into the envelope of a
common streaming format such as Real,
Windows Media, or QuickTime, and
• Serve the unicast or multicast stream.
• Can store the stream for VOD.
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All-In-One Box
Examples:
• STARBAK Torrent CE
• FVC Conference Server with Streaming Support
• Virtual Rooms Videoconference Service (VRVS)
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Combo Terminal and
Encoder
 Two standard devices…
• H.323 videoconference terminal
• Streaming encoder
 Are interconnected
• A/V out of H.323 terminal into A/V input of encoder
 Encoder can be just about anything
• Real, Windows Media, QuickTime; or MPEG-1,-2,-4;
unicast or multicast
 Video can be recorded and stored for VOD
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Terminals with Built-In
 Some high-end terminals such as
• Polycom FX
• Tandberg 880
 Can multicast the H.26x/G.7xx audio
and video in standard streaming
envelopes (QT, etc.).
 No ability to record for VOD.
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Application Service
Providers
 Many videoconference bridging service
providers also provide a streaming
option.
 The technology that an ASP will
employ will either be an All-In-One Box
or a Combination Terminal and
Encoder
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Pros and Cons
 Video and audio quality
• CON: Both All-In-One Box and Terminals with
Built-In repackage H.26x and G.7xx video and
audio.
– H.26x & G.7xx are not optimized for streaming. The
video quality is more susceptible to degradation due to
network congestion than made-for-streaming formats
such as Real and Windows Media encoders.
– H.26x doesn’t provide dynamic bandwidth adjusting
capability like Real SureStream and Windows Intelligent
Streaming.
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Just because…
You’re getting a Real, QT, or WM
stream out of an All-in-One Box, doesn’t
mean optimized-for-streaming encoders
are being used!
All-In-One Box and Terminals with BuiltIn DO NOT use the Real or WM
encoders. They stuff H.26x and G.7xx
encoded video and audio into Real,
WM, or QT envelopes.
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Pros and Cons
Video and audio quality
• PRO: Solution Combo Terminal and Encoder uses
optimized-for-streaming encoding formats.
– H.26x & G.7xx from the videoconference are decoded to
baseband video and audio and re-encoded in an
optimized-for-streaming format.
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Pros and Cons
Networking
• CON: Terminals with Built-In require IP multicast.
– Multicast is sparsely supported in the commercial
Internet.
– Multicast support in university and commercial intranets
is varied and typically not robust.
– Internet2 supports multicast.
– Terminals with Built-In are only feasible if your audience
is on multicast-enabled networks.
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Pros and Cons
Networking
• PRO: All-in-One Box and Combo Terminals and
Encoders support IP unicast and multicast
transmissions.
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Pros and Cons
 Operations and Management
• CON: Combo Terminal and Encoder can be
complex to manage
– Have to schedule and manage the encoder.
Videoconference scheduling systems don’t support
viewing the pair of devices as a single logical device.
 Features
• CON: Terminals with Built-In don’t have the ability
to record a videoconference.
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Initial set up
Management &
operation
Network
transmission
Transmission
speed
Perf under net
congestion
Record for VOD
All-In-One
Combo
Built-In
moderate to
complex
complex
simple
moderate
complex
simple
unicast or
unicast or
requires
multicast
multicast
IP multicast
fixed to speed flexible modem fixed to speed
of
to
of
conference
broadband
conference
fair to poor
yes
good
fair to poor
yes
only w/ extra
special
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Cost to support
a small
number of
concurrent
conferences
Cost to support
a large
number of
concurrent
conferences
All-In-One
Combo Term
& Encoder
Built-In
high
moderate
low
high
moderate-tolow
moderate
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Internet2 Commons
VC Streaming Service
 Utilizes STARBAK Torrent CE all-inone box
 Available to any Internet2 Commons
member who requests a conference
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Internet2 Commons
VC Streaming Service
 Simple web interface
• Video uses QuickTime, Windows Media Player, or
RealOne
 Can add slides and chat, if you want them
 Stream has about a 1 to 1 ½ second delay
over the actual videoconference
• Comparatively speaking, a very short amount of time
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Internet2 Commons
VC Streaming Service
 If you request that the Commons record
your conference, you will need to store the
stream on your own server.
 Can be played back in QuickTime or Real.
 When filling out the conference request
form, select streaming.
 You will need to describe the anticipated
audience.
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