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Anonymous
The sub-standards most likely to be met with in practice are detailed below: 1. Video Coding Standards H.261 Video CODEC For audio visual services; this defines the way in which the picture information is compressed and coded to enable transmission over low bandwidth networks. It is the baseline coding which is mandatory for most videoconferencing systems to ensure interoperability at a basic level. H.261 Annex D Graphics
Anonymous
Manufacturers may also choose to include proprietary enhancements, e.g. Polycom’s Siren Audio extends the audio bandwidth up to 14kHz to improve the sound quality. These proprietary enhancements are not international standards so only provide a benefit when used between products from the same manufacturer. Proprietary standards should not be confused with ‘options’ within the ITUT standards. The options are not mandatory but when incorporated will allow improved compatible communication between dissimilar equipment without problems.
Anonymous
Other, optional, sub-standards are defined to allow enhanced performance, e.g. H.243 provides for multipoint control function, i.e. when two or more sites conference there is provision for sending signals through a Multipoint Control Unit (MCU). H.281 provides for far-end camera control from the local site, H.282/H.283 provide the requirements for remote control of devices other than the camera, and T.120 provides for data exchange.
Anonymous
Within each ITUT umbrella standard, minimum mandatory standards are defined that will guarantee compatibility, albeit at a basic level, e.g. within H.320 provision must be made for H.261 video coding, G.711 audio coding and H.221, H.230, H.242 communications protocols. Similarly for H.323, the corresponding mandatory standards are H.261, G.711 and H.225/H.245 communication protocols. These mandatory requirements will allow all compliant products to communicate easily and effectively.
Anonymous
H.323 This is the umbrella standard for IP conferencing. It includes several sub-standards: H.261 defines the mandatory video Coder/Decoder (CODEC)* standard, whereas H.263 and H.264 define optional video CODECs. Similarly G.711 is the mandatory audio CODEC and G.729 one of several audio CODEC options. The complex operation of managing the data streams from the CODEC including calling, establishing a call, and controlling the various component parts i.e. video, audio and data is defined by two standards, H.225 and H.245.
Anonymous
Dr Syngen Brown of the University of London Computer Centre (ULCC) has made most helpful and detailed comments on the standards. Polycom® is a registered trademark of Polycom in the U.S. and various countries.  A videoconference link requires:
Anonymous
Anonymous
Software requirements: A modern web browser Quicktime 6.5 and above Windows Media Player (requires IE and Windows 2000, XP, Vista or 7) Java (standard edition) How to Use Live Videoconference Streaming The Streaming feature may be selected when a videoconference is being booked from the Confirm booking page (Step 3 of 3). The conference Booker should click Set conference options and tick the Videoconference streaming tick box.
Anonymous
Anonymous
Videoconferencing is a very powerful way to collaborate, with considerable potential benefits for education. However, like any communication technology, videoconferencing can be misused. Janet Videoconferencing is designed to be flexible so as to allow a wide range of educational uses. This inevitably means that safety relies more on end users and organisations making their own appropriate choices than on restrictions built into the services. This factsheet provides some guidelines on how to set up and use videoconferencing safely.