Overcoming Latency; Channels And Streams - PRESONUS StudioLive 24R Networking Manual

2 AVB Networking
2.5

Overcoming Latency

Overcoming Latency
2.5
2.6

Channels and Streams

AVB STREAM
Channel 1
Channel 2
Channel 3
Channel 4
Channel 5
Channel 6
Channel 7
Channel 8
The AVB switch guarantees that real-time audio data packets maintain
their timing without losing information. AVB switches do this by
allowing a maximum of 75% of each port to be used for AVB traffic.
This prevents non-AVB data from being delayed or lost.
When an AVB network is configured, the Talkers and
Listeners identify one another automatically.
SRP works with the 802.1Qav Queuing and Forwarding Protocol (Qav) to ensure that
once bandwidth is reserved for an AVB stream, it is locked down from end to end.
Qav schedule time-sensitive streaming information to minimize latency. Together,
SRP and Qav make sure that all reserved media streams are delivered on time.
In this way, the AVB network has some intelligence as to how much non-media
traffic as well as how many media packets are on the system at any given
time. This means that on an AVB network, the worst case travel time is known
throughout the entire system. Because of this, only a small amount of buffering
is needed, lowering latency to 2 ms over seven switch hops on a 100 Mbps
Ethernet network. On gigabit networks, even lower latencies can be achieved.
AVB Streams can be thought of as the pipeline that carries a predefined
number of channels between two or more AVB devices. In a PreSonus
StudioLive Series III mixer, for example, there are seven input streams
and seven output streams available, each carrying eight channels.
It should be noted that each stream can carry any combination of eight channels.
The source for the eight channels within each AVB Send stream can be freely
routed from any input channel or bus on a StudioLive Series III mixer via the
Digital Patching menu. For complete information on Digital Patching, please refer
to the StudioLive Series III Owners Manual and UC Surface Reference Manual.
In addition to audio channels, each stream can carry clocking information from
the network's global clock. Like all digital systems, devices on an AVB network
must receive media clock from a master source to maintain proper sync.
StudioLive™ Series III
AVB Networking Guide
7