6
When Content is received
a number of layout options are available.
Main Monitor (includes Menus)
Second Monitor
Far site big, near site small
Content full screen
Near site big, far site small
Content full screen
Near and far sites, same size, side
by side
Content full screen
Far site full screen
Content full screen
The Polycom® high definition camera has a native resolution of 1920 x 1080
(1080p) it has a fixed focus lens and tilts with the monitor adjustment. A 2x digital
zoom is available but unlike an optical zoom its use just degrades the image. A
manual privacy shutter control is provided above the camera.
A feature of the HDX system is People ‗on‘ Content (conventionally called
―Chroma Key‖ or ―Colour Separation Overlay‖) to create an artificial background
behind a presenter. For example a weather presenter could be superimposed over a
map of the UK (derived from a PC image). This requires the presenter to be
positioned in front of a plain green background and viewed by the HD camera. The
green areas of the image (i.e. not the presenter bits) then cause an electronic switch
to select the appropriate parts of the map for superimposition. Unfortunately the
quality of these ―chroma-key‖ images is very variable and is critically dependant on
the quality of the lighting on the presenter. It can be very difficult to reduce the
‗shimmering‘ effect around the edge of the presenter image.
The optional high definition MCU provides four (host HDX CODEC plus three
remote sites). The speed of each connection is dependent on the total number of
sites in the MCU conference and the bandwidth capability of the CODEC. The
MCU option was not available on the evaluation systems.
During an H.323 call a second unidirectional video channel (Content) is provided
through H.239, ―People‖ being the normal conferencing channel. Thus video from
the camera and a second source e.g. a PC image could be transmitted
simultaneously and displayed on two monitors at the remote site. For People and
Content the bandwidth may be dynamically allocated between each channel or split
in the ratios, 50/50, 90/10 or 10/90 up to the limits of the maximum available
connection speed.
The HDX system is capable of transmitting and receiving two simultaneous high
resolution (1080p at 30fps) images. The high definition high frame rate Content
channel is a new development that enhances the overall conference experience.
Several audio formats are supported by the CODEC. Polycom has implemented the
Siren 22 audio protocol with 22KHz analogue audio bandwidth, including
StereoSurround™. The system captures stereo by using the two monitor
microphones to create a stereo image.
A separate stereo audio input using a 3.5mm mini jack connector allows for
straightforward interfacing to a PC or laptop. A useful feature mutes Content audio
on the local and remote loudspeakers until Content is selected for transmission.
