Video switching has encountered two technology trends that together have changed tasks in the professional studio radically. Native signals used in video editing evolved from analog to SD digital, then quickly to HD and several higher-bandwidth standards.
At the same time, video aggregation that once was characterized by digital streams, increasingly took advantage of packet-switching technologies, with Ethernet showing particular dominance as a protocol at Layer 2.
Of course, packet switching as defined by the professional studio is quite different from the technology used in the enterprise LAN, or even the WAN backbone.
It is more similar to advanced storage networks, in taking advantage of the Jumbo Frames technology for Ethernet developed by Silicon Graphics Inc., as well as my serial protocols used in conjunction with Ethernet, such as Fibre Channel and Myrinet.
When professional studio mixers and switchers primarily manipulated SD and composite video signals, hardware needs were significant, but did not always defined the highest performance switches or routers in communications markets.
The slow but steady arrival of 3G HDTV, 3D HDTV, 4K2K, and Super Hi-Vision (Ultra HD) makes it more important to move the speed of switching to tens of gigabits per second. This speed demand will be accelerated further by expansion of local, national and international HD productions and the anticipated move to 1080p and 3D broadcasts.
Meanwhile, the effort to move the first stage of editing and mixing video content from centralized studios to remote digital TV vans has placed new demands on hardware to reach new milestones in low power and high integration.
These two goals now exceed the demands for signal quality that will maintain uninterrupted broadcasts to the viewing audience. Changes in site-based video switching have followed two related trends favoring denser switches.
The arrival of IP gateways in video networks has made it possible in some network topologies for broadcasters to capture and transmit uncompressed HD video from remote sites.
Also, broadcasters seek to simplify overall transmission-system architectures through the use of denser, higher-performance switches that carry the potential of replacing bulky remote studio trailers that are often the size of semi trucks. Miniaturized video switching platforms could lead to reduced sizes, lower power and simplified architectures in remote transmission.
An emerging trend is the packetization of high-bandwidth traffic, a familiar trend that has played out in telecom and cable TV environments. In fact, if there is a partial bright side to the architectural demands of new video switching architectures, it comes in the packet-centric methodologies permeating digital video editing.
The video industry has evolved from analog input and composite traffic over RF cable, to emerging architectures featuring sophisticated control, scalability and embedded audio capabilities.
While video switches still push performance and scalability on a larger scale than multiport Gigabit Ethernet switches, the chip-level design shares more in common with packet switches, particularly in integrated low latency routing and Quality of Service packet prioritization methods.
The importance of shifting to an all-packet infrastructure for HD video can scarcely be over-emphasized. As in the case of telecommunication traffic, the shift to packet video will offer revolutionary consequences, something that has been recognized in recent years by the Society of Motion Picture and Television Engineers.
SMPTE’s series of favored Serial Digital Interface, or SDI standards, only recently began striving for interoperability with telecom and CATV packet traffic. The 3G-SDI interface, specifying a 2.97-Gbit/sec link, has been promoted as a replacement for dual-link HDTV SGI. Initial development work is being carried out on 10G-SGI and 12G-SGI, with a deliberate intent of mapping the higher-end standards into 10G, 40G, and 100G Ethernet.
In parallel with the SDI efforts, SMPTE also worked on a standard for Video Over IP, which has been realized in the new 2022 standard for Forward Error Correction.