Download - Streaming an H.323 Videoconference
Streaming Videoconferences
Egon VerharenTNC2004 H.323 TrainingJune 11, 2004Rhodes, Greece
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
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.
What Kinds of ThingsCan 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 on-
demand 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…
Interactive for Live Events
Streaming is a one-way delivery of media.
Participants in a live, streaming event can participate interactively (give feedback “the other way”) by:•E-mail to a conference facilitator•On-line chat
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 provider
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.
All-In-One Box
Examples:• STARBAK Torrent VCG• FVC Conference Server with Streaming Support• Virtual Rooms Videoconference Service (VRVS)
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
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.
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
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.
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 Built-In 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.
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.
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.
–Terminals with Built-In are only feasible if your audience is on multicast-enabled networks.
Pros and Cons
Networking• PRO: All-in-One Box and Combo Terminals and Encoders support IP unicast and multicast transmissions.
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.
• CON: Data collaboration recording is difficult!!
fixed to speed of conference
flexible modem to broadband
fixed to speed of conference
Transmission speed
only w/ extra special tech
yesyesRecord for VOD
fair to poorgoodfair to poorPerf under net
congestion
requiresIP multicast
unicast ormulticast
unicast ormulticast
Networktransmission
simplecomplexmoderateManagement &
operation
simplecomplexmoderate to
complexInitial set up
Built-InComboAll-In-One
moderate-to-low
highmoderate
Cost to support a large number of concurrent conferences
lowmoderatehigh
Cost to support a small number of concurrent conferences
Built-InCombo Term
& EncoderAll-In-One
Internet2 CommonsVC Streaming Service
Utilizes STARBAK Torrent VCG all-in-one box
Available to any Internet2 Commons member who requests a conference
Internet2 Commons VC Streaming Service
Simple web interface• Video uses QuickTime, Windows Media Player, or
Real
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