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Lecture Broadcast
March 5th, 1998
Technical Settings

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The Lecture took place in AIT Center auditorium, the room can host 3 to 400 persons.

The Lecture was conducted using two overhead projectors. A video tape was also shown to the attendees.

The Lecture was broadcasted on 3 different formats:

There are two majors things that could be learned from this experince:

The setting of the equipment was as follow:


(blue lines are for computer network, red lines are for audio, green lines are for video)

RealEncoder

 The RealEncoder captures the sound and video and sends it to the RealServer for broadcasting.

The settings of the software were as follow:

RealServer

 The RealServer broadcasts the the audio and video streams produced by the RealEncoder.

Mbone

 Multicast on Mbone was done throught AI3 satellite link. The settings for the softwares were as follow:

AI3bone

 Multicast on AI3bone was done throught AI3 satellite link, this was hight bandwidth broadcasting dedicated to AI3 project only. The settings for the softwares were as follow:

Line Attenuator

 This important, home made gadget, allows to adapt the level and impedance of an audio line-out (from VCR, preamplifier, audio mixer, etc.) to the level and impedance of a microphone. This allows to connect the line-out to the microphone entry of the sound card of a computer.

Synopsis of the Line Attenuator Line Attenuator
This device had to be developped after we noticed that many video conferencing software will only accept audio input from the microphone, they could not be set-up to get imput from the line-in connector of the sound card. That limitation was not permitting to use several microphones, via an audio mixer for example, or to feed the sound from a video tape.

Audio Mixer

Public addressed audio mixer, with 6 channels:

Equalizer function can be a plus, but it needs fine tunning.

Audio Mixer

The audio mixer is used in mono mode as only one sound channel is feed to the computers.

Video Mixer

Public addressed video mixer, with 2 video inputs, monitor, reccord and preview outputs. The number of transition effects is not really a matter as most of the time the frame rate will not be high enough to permit real effects like wiping, mixing images, etc.

VCR for Reccording

Public addressed VCR with reccord function, used to keep a video archive of the event, this video can be used to built up a library of video conferences in the future.

Control

Public addressed monitor, used to control the image that is reccorded. It also allows to control the image that is sent to the computer.

Auditorim Sonorisation

Sonorisation of the auditorium was provided by AIT center technician. The sound was output to the audio mixer for feeding to the computers.

Camera

Public addressed camcoder, 12x zoom, 0.4 Lux sensitivity, built in LCD screen for easy use by the cameramen.

VCR for Playing tape

Public addressed VCR that was used to display the tape that was part of the lecture. This tape was displayed on a screen, through a CRT projector, the video signal was also fed to the video mixer for direct sending over Internet.

Preview Monitors

Public addressed monitors used at the video control place to view the image from each camera, before they can be send to the computers.

Video Switch

Home made, 4 channels, rotary switch, that allows to select what source is feed to the video mixer.

Video Switch

This gadget was needed as we had up to 3 sources to mix: 2 cameras, plus the tape that was displayed.

This page is maintained by Olivier Nicole