Axon Introduces Distribution of Uncompressed Video Over IP (AVB)
Part of the company’s challenge is demonstrating to the broadcast industry how IP-based technologies can be empowering drivers for the market. Leading to the development of an entirely new generation of infrastructure products and creating new ways of working.
Some of this technology is with us today. The Axon demonstrator is used to show that already it’s possible to distribute uncompressed video over an IP infrastructure using IEEE802.1 Audio Video Bridging (AVB) technology. This represents the first step in developing a strategically important series of new products: a proof of concept in the distribution of packetized video over an Ethernet network.
Since packetized data transmissions lack a physical clock, the data has to be accepted by a clock which is recovered and synchronized via the same Ethernet network. The IEEE802.1as technology is used for this purpose. In this application, one node in the setup acts as a “clock-Master” on the AVB network, whilst a second node is “slave” to this unit. Packetized clock information is exchanged between master and slave to define the delay between the two clocks. The slave clock alters its settings to perfectly match the Masters Clock frequency, so that both clocks are synchronized. When adding additional slave nodes to the network, they all follow the same approach ending up with all endpoint fully synchronized asynchronous network.
To ensure sufficient network bandwidth to setup AV streams between endpoints, a reservation protocol is implemented. Bridges (AVB capable switches) have the capability to reserve bandwidth for AV streams. By default 75% is reserved for AV streams. When setting up a stream available bandwidth is checked and when available, a connection is created. Also, this allows the use of AV streams together with traditional data on a single network.
Axon has built a demonstrator to prove this technology. On the Synapse platform one endpoint is used to act as a Master unit and sources uncompressed SD-SDI. This is converted to packetized data and transmitted to a second endpoint which is a slave on this network. This endpoint converts the packetized video to traditional SD-SDI and shows this on a monitor. This second endpoint on itself also has an SD-SDI input and transmits a second SD-SDI stream over the Ethernet back to the Master unit, which converts this back to SD-SDI. A block diagram of this setup is shown in the figure below.