DMA OperationsGuide Introduction to the Polycom DMA System
4Polycom, Inc.
SVC Conferencing Support
This version of the Polycom DMA system supports the Annex G extension of
the H.264 standard, known as H.264 Scalable Video Coding (SVC), for both
point-to-point and multipoint (VMR) calls.
SVC is sometimes referred to as layered media because the video streams
consist of a base layer that encodes the lowest available quality representation
plus one or more enhancement layers that each provide an additional quality
improvement. SVC supports three dimensions of scalability: temporal (frames
per second), spatial (resolution and aspect ratio), and quality (signal-to-noise
ratio).
The video stream to a device can be tailored to fit the bandwidth available and
device capabilities by adjusting the number of enhancement layers sent to the
device.
For multipoint conferencing, the MCU doesn't have to do processing-intensive
mixing and transcoding to optimize the experience for each device. Instead, it
simply passes through to each device the enhancement layers that provide the
best quality the device can support.
Polycom’s SVC solution focuses on the temporal and spatial dimensions. It
offers a number of advantages over standard AVC conferencing, including:
Improved video quality at lower bandwidths
Improved audio and video error resiliency (good audio quality with more
than 50% packet loss, good video quality with more than 25% packet loss)
Lower end-to-end latency (typically less than half that of AVC)
More efficient use of bandwidth
Lower infrastructure cost and operational expenses
Easier to provision, control, and monitor
Better security (end-to-end encryption)
Polycom’s SVC solution is supported by the Polycom RealPresence Platform
and Environments, including the latest generation of Polycom MCUs and
RealPresence room, personal, desktop, and mobile endpoints. Existing RMX
MCUs with MPMx cards can be made SVC-capable with a software upgrade,
and doing so triples their HD multipoint conferencing capacity.
See also:
“Introduction to the Polycom DMA System” on page1