Audio Video Bridging

Audio Video Bridging (AVB) is a common name for a set of technical standards that provide improved synchronization, low latency, and reliability for switched Ethernet networks.

AVB includes layer 2 protocols to reserve connection bandwidth and prioritise network traffic, which guarantee precise sync clock and low transmission latency for each stream.

The IEEE 802.1BA is an umbrella standard for these three principal technologies, which defines application-specific configurations and operation procedures for devices in switched audio video networks.

The new layer-2 configuration protocols work with backward-compatible extensions to the Ethernet 802.1 frame format; such minimal changes allow AVB devices to coexist and communicate in standard IT networks, however, only AVB-capable switches and endpoint can reserve network resources with admission control and synchronize local time to a master clock, which is required for low latency time-sensitive traffic.

IEEE Std 1722-2011[8] for a Layer 2 Audio Video Transport Protocol (AVTP) defines details for transmitting IEEE 1394/IEC 61883 streams and other AV formats, setting the presentation time for each AV stream, and manage latencies from worst case delay calculated by the gPTP protocol.

[15][16] In 2018, the Avnu Alliance announced the Milan initiative to promote interoperability of AVB devices and provide product certification and testing.

[18] One of the possible application of DetNet is professional audio/video, such as music and film production, broadcast, cinema, live sound, and large venue (stadiums, halls, conference centers, theme parks, airports, train terminals, etc.)

The stated goal is to enable geographically distributed, campus- or enterprise-wide Intranet for content delivery with bounded low latency (10-15 ms).

[19] Large-scale AVB networks, like those used by the ESPN SportsCenter "Digital Center 2" broadcast facility, which hosts multiple individual studios, are laid with many miles of fiber and have ten Tbit/s of bandwidth for a hundred thousand signals transmitted simultaneously; in the absence of standards-based solution to interconnect individual AVB segments, a custom software-defined networking router is required.

Wiring of a patch bay of an outside broadcasting van
Figure 2 - AVB Connections