AS IP-BASED OPERATIONS SPREAD , ETHERNET IS HERE TO STAY BUILDING BLOCKS FOR STUDIO VIDEO OVER IP
By SCOTT BARELLA , CHIEF TECHNOLOGY OFFICER , UTAH SCIENTIFIC
As the broadcast industry continues its march toward a future defined by all-IP-based operations and driven by commodity IT systems , it ’ s amusing to consider that the whole thing hinges on a technology rooted in the early 1970s . Tracing its origins to the Bob Metcalf / David Boggs project at Xerox PARC , Ethernet became an IEEE standard for LAN , MAN , and WAN networking back in 1983 — long before the internet was anything close to a household word .
Fast-forward to today , when it ’ s difficult to imagine any type of network that doesn ’ t rely extensively on Ethernet . In television studios , Ethernet was traditionally delegated to configuration and control networks . More recently , Ethernet has offered a vehicle to carry compressed transport streams , introducing a new way of thinking and a departure from the older pulse-based streams for carrying compressed video using Asynchronous Serial Interface ( ASI ).
Now , Ethernet is once again the star as the broadcast industry undergoes its latest transformation . Soon , digital SDI signals will be replaced by Ethernet packets transported over all-IP-based networks . With the new SMPTE ST 2110 standard for uncompressed IP video and audio about to come online , it behooves broadcast engineers to have a broad and deep understanding of Studio Video over IP ( SVIP ) in the uncompressed domain using Ethernet .
While there are many aspects to the use of Ethernet for SVIP , only a few key pieces — IP , UDP , and RTP timestamped packets — relate to elementary audio , video , and data streams . A keen understanding of these elements will put engineers far down the road in their ability to manage the new IP topologies for video and audio .
MULTICAST SVIP
First , let ’ s take a look at the basic structure of Ethernet – beginning with subnetworks ( aka subnets ). These use a four-octet address scheme ( for example , the private address of 192.168.1.10 ), followed by a netmask of 255.255.255.0 to further divide the network into smaller sizes in the address range . Within a subnet , any address can “ speak ” with another address as long as the second address uses the first three octets ; e . g . 192.168.1 . X . Some organizations connect themselves using a wide area network ( WAN ) to carry data from different subnets within their private network . To give an example , a station in Denver might need to deliver data to an affiliate station in New York . The Denver LAN subnet might be 192.168.1.0 but the one in New York might be 192.168.20.0 . The WAN would make it possible for these two subnets to communicate .
The previous example is an Ethernet unicast connection in which the address acts as the sender and another address within the subnet acts as the listener . But broadcasting – by its very definition
Broadcast Beat Magazine • www . broadcastbeat . com • 85
AS IP-BASED OPERATIONS SPREAD,
ETHERNET IS HERE TO STAY
BUILDING BLOCKS FOR STUDIO VIDEO OVER IP
By SCOTT BARELLA, CHIEF TECHNOLOGY OFFICER,
UTAH SCIENTIFIC
As the broadcast industry continues its march
toward a future defined by all-IP-based opera-
tions and driven by commodity IT systems, it’s
amusing to consider that the whole thing hinges
on a technology rooted in the early 1970s. Tracing
its origins to the Bob Metcalf/David Boggs proj-
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