Polycom WEBCOMMANDER 8 - Manual (Page 232)

MGC WebCommander User’s Guide
7-22
Video Conference Types
Video Conferences can include both video and audio only participants. In a
video conference, the participant can connect to the conference using
different network connections: ISDN, H.323, ATM, MPI (serial connection)
and T1-CAS (if the MCU is configured to accept T1-CAS participants in
video conferences). One conference is defined for all the interface types. The
usage of ATM, ISDN and H323 is defined per participant in the Participant
Properties – Identification dialog box. The line rate for all participants is
defined at the conference level, taking into account the maximum line rate
possible with each network and endpoint.
Video conferences are categorized according to their video layout display
(Video Session) and the method in which the video is processed by the MCU:
Video Switching - A conference in which all participants see the same
picture (video). The current speaker is displayed in full screen on all the
participants endpoints and the switching between participants is
voice-activated; whenever a participant starts to speak, he or she
becomes the conference speaker and is viewed on all screens. This
conference type does not use the video card resources, therefore all
participants in the conference must use the same line rate, and the same
video settings.
This conference type does not use the MCU video resources.
In Video Switching conferences, the Highest Common Mechanism is
enabled for the video parameters, allowing the system to select the best
video parameters that can be supported by all the endpoints currently
connected to the system, and to dynamically change them when a new
endpoint joins or leaves the conference.
• Transcoding - A conference in which participants use different line
rates, video, audio and data formats, while maintaining the highest video
and audio capability that each participant can achieve with his or her
endpoint. As in a Video Switching session, the current speaker is
displayed in full screen on all the participants’ endpoints and switching
between participants is voice-activated. Because each video participant is
connected using the highest possible video quality, this conference type
requires appropriate video card resources for processing inputs from the
different endpoints. Transcoding is performed on the following: Line
rate, restricted/non-restricted; Audio algorithm; Video format; Video
frame rate; Aggregation mode (Bonding/H.221); different data rates