Worzyk FH Anhalt Telemedizin WS 03/04 Einführung - 1 Video Conference
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Video Conference
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Definition
A video conference is a virtual meeting of two or more spatially separated dialogue partners, which can communicate in real time over audio and video with each other. At the same time all data (audio, video, text) can be digitized, handled simutanously and exchanged among the partners.
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components• Camera – Display
– Transmission of moving pictures in real time
• Microphone – Loudspeaker– Transmission of sound in real time
• Chat– Written Communication
• Whiteboard– Concurrent drawing, writing, inserting
• Share programs– using Word, PowerPoint from the partner
• Transfer of data– Transfer of any data
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Transmission
CodecCodierer/Decodierer
CodecCodierer/Decodierer
ISDNIP
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reduction of dataMPEG
motion pictures expert group
Spatial redundancyAreas with same brightness
and color can be summarized. The first pixel is accurately transferred, then an instruction for the repetitions follows
http://www.broadcastpapers.com/data/ON2Compression01.htm
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reduction of dataMPEG
Temporal redundancySome parts in the scene do not
change from one pictuer to the next picture. So it is only necessary to transmit the changing parts of the
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reduction of dataMPEG
Statistical Redundancy
PredictionMovements which are
known from the past are predicted to the future and only unpredictable parts of the picture are transmitted,
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reduction of dataMPEG
DatastreamIntra picture: compleate
picture reduced by Spatial redundancy
Predicted picture: predicted by a previous picture
Bidirectional predicted picture : predicted or calculated by previous and subsequent pictures.
I B B P B B P B B I
http://bmrc.berkeley.edu/frame/research/mpeg/mpeg_overview.html
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http://www.lrz-muenchen.de/services/schulung/unterlagen/bildkommunikation/sld031.htm
http://vcc.urz.tu-dresden.de/vc-handbuch/
H.323Terminal
H.323Terminal
H.323Terminal
ISDNTerminal
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Videoconferencing Room
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ExamplesBremerhaven Berlin
DuisburgGarching
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interior design
• Sufficient seats, visible from the camera• Display must be visible from each seat• No blind area• Sufficient lightning, no mixed light (blue
daylight and red bulb light)• Acoustic shielding• Monochrome, neutral background
http://www.mcsquared.com/videoconference.htm
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Video
• Camera to track the speaker should be movable with programmable positions
• Document camera or presentation camera should be movable
• For each camera one display at the own and at the remote site
• Speakers camera should be directly above the assigned display
• Control panel
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Audio
• Shield external sound source– Traffic, engines, elevators, Air conditions,
• Avoid reverberation in the interior• Same distance to the microphone for
each speaker• A single person should use a headset• High quality loudspeakers• Mixer
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Lighting
• Illumination uniformity of the room• Diffuse light• No cast shadow• No reflection on the displays• No direct light to the camera
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During the conference
• The sound may come in delay (probably use a seperate sound connection)
• eye contact is not possible, so position camera and monitor as close as possible side by side
• Inform the partner about each action– Turning off the micro, freeze image, someone is
leaving or comming, …
• Little gesture
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Examples
http://www.onko-kids.de/Projekt/video.htmhttp://www.screentherapy.de/index.htm
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Installation of NetMeeting
• Check headphone or loudspeaker• Connect the microphone• Check the microphone• CAll NetMeeting
– No registration to the directory server
• Connect to the partner via IP address
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Weitere Informationen
http://vcc.urz.tu-dresden.de/vc-handbuch/http://www.uni-essen.de/videokonferenz/http://www.ruhr-uni-bochum.de/rz/dienste/internet/vkonf/http://it-resources.icsa.ch/SoftWare/VGuideD.htmlhttp://it-resources.icsa.ch/SoftWare/VGuideD.htmlhttps://www.vc.dfn.de/doku/vortraege/folien.dd/2_rahmenbedingungen_20020424.pdf
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Videoconference systeme in our Department
NetMeeting– One camera– ein microphone (Sound in one direction)– Transmission of
• Presentation• Shared Whiteboard• Chat
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Videoconference systeme in our Department
Interkom + Polycom2 movable CamerasCamera controll 6 MicrophonesMicrophone controll
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Konferenzschaltung
Interkom Polycom
Internet