Audio Video Bridging (AVB) is a new Institute of Electrical and Electronics Engineers (IEEE) industry- wide standard that is being developed for the distribution of digital audio and video signals over Ethernet networks. This proposed standard is something that will affect all of us in the near future. The standard is being created by the IEEE 802.1 Audio Video Bridging Task Group. The AVB standard is made up of four different publications: 802.1AS, which focuses on time synchronization issues (based on the current IEEE 1588 standard); 802.1QAV forwarding and queuing enhancements for streaming media; 802.1QAT for stream reservation enhancements; and the transport protocol outlined in IEEE 1722.
One company actively involved in the AVB Task Group is Harman International. According to Rick Kreifeldt, vice president of the System Development and Integration Group, Harman has been working on this project for two and a half years. “This is an industry-wide standard initiative that is being driven by the players in the computer engineering and networking industries to develop standards-based methods for synchronized, low latency, guaranteed quality of service transmission of audio and video over the
Ethernet.”
Today the technology used to distribute high-quality audio and video over Ethernet is mainly done using proprietary technology. One of the dominant players in this space is Cirrus Logic’s CobraNet. Typical users of this technology include large installations such as sports stadiums, theme parks, the U.S Senate, and others. Harman is one of the main suppliers of CobraNet products.
Network switches is one technology that will be greatly affected when the standard is adopted. “They are making changes to the switches to guarantee that the data travels at really low latency and to guarantee that the data can not be interrupted by normal Ethernet data traffic,” says Kreifeldt. In a typical network environment, some packets like email receive the same priority as audio and video streams. This can cause collisions and other issues, such as dropped frames, that are not acceptable to users viewing the streams.
For the new AVB standard to be successful, not only do these issues need to be addressed, but the AV industry and manufacturers need to work together to resolve them. “In the pro audio world, there are several different proprietary networks out on the market,” says Kreifeldt. The AVB task group is trying to create a standard that everyone can agree on. “Rather than it being a companyowned technology, this is the first one that is an industry-wide standards based approach to come out of the IEEE.”
It all sounds good, but there are some challenges to overcome for AVB. According to Kreifeldt, one challenge for the task group is to attain broad market appeal, which will require pushing the technology in high-end installations and large corporations down to the average user. “Today the process is very manual and requires someone who can setup a network, and not a lot of people have the ability to do this. We are trying to make AVB as friendly as possible. We want all the mechanisms to be automatic and bulletproof,” he adds. Kreifeldt expects adoption of this standard to be approved within the next two years. He said that the AVB standard should reach technical stability by the end of the calendar year and that a ratified standard is “likely” within a year after that. It is also important to point out that even though a new standard is on the horizon, Harman will continue to support products like CobraNet for the foreseeable future, and the standard will have provisions included for backward compatibility.