ClearOne Digital Media - Manual (Page 14)

pg 14 StreamNet Digital Media and System Design Reference Guide
Common AV Signals and Interfaces
How AVB came to exist.
An effort was started within the IEEE 802.3 (Ethernet) working group to define a “Residential
Ethernet” which would directly address the challenges of A/V streaming. However this work
quickly moved over to the IEEE 802.1 working group. In particular, the group wanted to
ensure the technology was scalable from consumer applications in the home and car, all the
way up to high professional standards.
As explained previously, there is nothing more important than time synchronization when
distributing audio and video signals. To achieve this AVB devices periodically exchange
timing information. This precise synchronization has two purposes:
1 . To allow synchronization of multiple streams.
2 . To provide a common time base for sampling and receiving data streams at a source
device, and presenting those streams at the destination device with the same relative
timing.
The protocol used for maintaining timing synchronization is specified in IEEE 802.1AS, which
is a tightly constrained subset of another IEEE standard (IEEE 1588), with extensions to
support IEEE 802.11 and also generic “coordinated shared networks” (examples include
some wireless, coaxial cable, and power line technologies).