Previous: Multimedia Conferencing and the Responsibilities of the Partners
Up: Multimedia Conferencing and the Responsibilities of the Partners
Next: Audio-visual Coding
Previous Page: Multimedia Conferencing and the Responsibilities of the Partners
Next Page: Audio-visual Coding
As stated in the previous sections, voice, video and computer data are to be shared amongst a distributed group of users. In the MICE project the users are part of the research community. We have divided the requirements into four classes of service:
This is not the only way that the services could have been classified - how they emerge is explained below. Since the existing research networks are acting as carrier networks - and these are largely packet-switched services - most of the conference activities are carried out over these.
Full bandwidth video requires about 120 Mbps bandwidth; this would be costly, and could not be carried by the existing research networks. Therefore, compressed video has to be used. There are quite a large number of compression schemes available, but since MICE is committed to using international standards wherever possible, we have agreed to use the international H.261 standard [5]. This can be provided by special codecs, or at a reduced rate by software in some of the more powerful workstations. Both approaches will be pursued.
We do not expect to have enough bandwidth available to carry multi-way high quality video to all sites. For this reason, we will use a hublet approach for at least some of the conferences: all the video goes to one site (initally the CMMC at UCL), where it is multiplexed and retransmitted to all participants. The functions of the hublet are explained in detail in section 2.6. One function is to relay between different coding schemes - e.g between stations using codec hardware and reduced performance ones doing the codec function by software.
The basic philosophy adopted by MICE is that participants should be free to use any equipment, provided it conforms to certain external standards. At the same time, the project is committed to produce a reference implementation which is documented and supported by one or more named participating organisations.