RMX 2000 Administrator's Guide Version 7.6.1 - Polycom

Polycom RMX 1500/2000/4000 Administrator’s Guide
Conferencing Parameters
Standard Conferencing Parameters
When defining a new video Profile, you select the parameters that determine the video
display on the participant’s endpoint and the quality of the video. When defining a new
conference Profile, the system uses default values for Continuous Presence (CP) standard
conferencing. Continuous Presence conferencing enables several participants to be viewed
simultaneously and each connected endpoint uses its highest video, audio and data
capabilities up to the maximum line rate set for the conference.
The main parameters that define the quality of a video conference are:
• Line (Bit) Rate - The transfer rate of video and audio streams. The higher the line (bit)
rate, the better the video quality.
• Audio Algorithm - The audio compression algorithm determines the quality of the
conference audio.
• Video protocol, video format, frame rate, annexes, and interlaced video mode - These
parameters define the quality of the video images. The RMX will send video at the best
possible resolution supported by endpoints regardless of the resolution received from
the endpoints.
— When Sharpness is selected as the Video Quality setting in the Conference Profile, the
RMX will send 4CIF (H.263) at 15fps instead of CIF (H.264) at 30fps.
— H.264 High Profile protocol provides better compression of video images in line
rates lower than 384 Kbps and it will be automatically selected for the endpoint if it
supports H.264 High Profile. If the endpoint does not support H.264 High Profile,
the RMX will try H.264 Base Profile which provides good compression of video
images in line rates lower than 384 Kbps (better than H.263 and not as good as
H.264 High Profile).
— When working with RMXs at low bit rates (128, 256, or 384Kbps), HDX endpoints
will transmit SD15 resolution instead of 2CIF resolution.
When using a full screen (1x1) conference layout, the RMX transmits the same
resolution it receives from the endpoint.
• Lost Packet Recovery (LPR) - LPR creates additional packets that contain recovery
information used to reconstruct packets that are lost during transmission.
• Video Clarity - Video Clarity feature applies video enhancing algorithms to incoming
video streams of resolutions up to and including SD.
• Supported resolutions:
— H.261 CIF/QCIF – Is supported in Continuous Presence (CP) conferences at
resolutions of 288 x 352 pixels (CIF) and 144 x 176 pixels (QCIF). Both resolutions
are supported at frame rates of up to 30 frames per second.
— H.263 4CIF - A high video resolution available to H.263 endpoints that do not
support H.264. It is only supported for conferences in which the video quality is set
to sharpness and for lines rates of 384kbps to 1920kbps.
— Standard Definition (SD) - A high quality video protocol which uses the H.264
and H.264 High Profile video algorithms. It enables compliant endpoints to
connect to Continuous Presence conferences at resolutions of 720X576 pixels for
PAL systems and 720X480 pixels for NTSC systems. For more information, see
"Video Resolutions in CP Conferencing” on page 2-1.
1-6 Polycom, Inc.