Re-Imagining Routing Switchers

As the mission of television stations evolves, the underlying technology of routing video, audio, data, sync, time of day, tally and metadata through broadcast plants must also evolve. But does that mean you need an all IP infrastructure? Maybe not.

Were one to take as serious the various announcements made, and demonstrations offered by vendors of Commercial Off-The-Shelf (COTS) IP network switches, the video routing switcher (also known as a router) is as obsolete as a monochrome camera. However, the basic system designs from current vendors reveal that switching in their systems is managed by a completely new device. It is called an Orchestrator.

These orchestrators are the antithesis of commercial, off-the-shelf devices, for they have no other purpose than to manage switching media flows in IP network switches. Given enough time, orchestrators will no doubt become as capable as most of today’s routing switchers.

Consider a different solution

Graphic Processing Unit (GPU) video cards are COTS components, not COTS devices, that provide tremendous processing power while consuming little energy. Internally, GPUs are made of thousands of optimized parallel processing cores. GPUs speak in compressed, and some uncompressed, video and audio as their mother tongue.

Beyond video, their processing cores have made quick work of once impossible tasks. A video gamer in a basement with a few hundred dollars and some open source code can now use the brute force of GPUs to crack once-sacrosanct 256 bit security keys in a month or less. Previously, such feats would have required lashing together hundreds or thousands of personal computers.

Corporate management might not readily realize how value is derived from a device that can connect any input source to any output destination in the blink of a video frame. Adopting a switching fabric made of inexpensive, jittery network switches that might work almost as well as last decade’s router is very tempting.

By embracing COTS components and new architectures, router vendors can overcome the threats posed by IP network switches while their broadcast station customers can better address current and foreseeable future needs. Rationalization of workflows and fundamentally new approaches to routers with much wider capabilities are required.

What is a broadcast TV station?

Not so long ago, a television plant delivered a single media output per RF channel, with only one RF channel per plant, and selected content from among one or more satellite dishes and several internal live and playout sources. The left side of the graphic below illustrates that antique of a television station. Video and accompany audio arrived in the same form in which it was processed and edited and left the plant in the same form.

Subsequently, duplicate output feeds to cable systems were added, then feeds to direct broadcast satellite providers. Often all that was required was to insert a distribution amplifier in the output path. The move towards digital broadcasting enabled broadcasters to add additional programming services while station consolidation meant that some TV stations operate multiple, independent RF channels, adding complexity to broadcast plants.

Now, viewers have access to a virtually unlimited number of video sources, some curated such as Netflix, and many not, such as YouTube.com. Broadcast stations, where content is not selected by algorithms but by people, remain as viable and almost as important as ever was the case.

Figure 1. In right portion of the image above, video and audio signals in a modern facility are shown connected to multiple outside destinations. Compare that complexity with the traditional router model (left) of X-number of inputs selectively routed to one output.  (click to enlarge image).

Figure 1. In right portion of the image above, video and audio signals in a modern facility are shown connected to multiple outside destinations. Compare that complexity with the traditional router model (left) of X-number of inputs selectively routed to one output. (click to enlarge image).

Video and audio now enter and leave TV stations in multiple forms using a variety of transports, coding and codecs. More than adding a distribution amplifier is required to support multiple linear outputs, streaming media and video on-demand. Many stations also furnish cable systems independent program services tailored for linear cable. This complexity is illustrated on the right side of the graphic to the left.

Internally, stations employ up-, down- and cross-converters, scalers, transcoders, de-interlacers, framestores, embedders, de-embedders, encoders, decoders and other gear to transform various input sources to the forms needed for editing, playout and output.

IP transport brings tremendous new capabilities

Transporting multiplexes of compressed video and audio using IP networking is robust and reliable, whether the task is conveying emission streams over 'noisy' IP networks, or remotes that use bonded cellular, IP microwave, IP satellite links. Commercial solutions for encapsulating all flavors of SDI over IP networks (SMPTE ST-2022-6) have been available at reasonable price points for years.

Work is ongoing at the Society of Motion Picture and Television Engineers (SMPTE), based on the work of the Alliance for IP Media Solutions (AIMS) and others to standardize a more bit-efficient approach to carrying uncompressed media streams over IP networks. By demultiplexing embedded audio, video, captioning, data and metadata from video and encapsulating each into distinct packet streams while discarding unneeded vertical and horizontal blanking intervals, this work will lead to more flexibility within and between broadcast plants.

Beyond these features and advantages, the most important characteristic of IP networking is the inherent full-duplex bidirectional pathways. An IP media flow can coexist with reverse flows over the same path employing the same or different encoding.

Video, audio and associated metadata from a camera or switcher can travel in one direction while the reverse direction carries a confidence flow along with tally, time code, sync, telemetry and control streams.

To embrace these characteristic possibilities of IP transport, entirely new bidirectional switching and processing fabric is a very new need for routing switchers.

Routers need not remain ‘commoditized’

Once embedding audio and metadata into uncompressed video streams became the norm with widespread adoption of SMPTE Serial Digital Interface (SDI) protocols, routers entered the slow and often painful path of commoditization. In a commoditized market, features of competing products become much less important to buying decisions than purchase and operational costs. To a certain extent, this commoditization has been masked by the long replacement cycle for routers, inertia and the sunk cost of router frames and cards.

If there is any doubt that product differentiation has decreased, the recent forays IP network switch vendors are fielding must be instructive. The market for IP network switches is a very mature commodity market and vendors are looking for new fields of play. COTS network switches, combined with orchestrators, are more complicated and offer fewer features than do routing switchers, but arguably at lower cost.

About a decade ago, mobile telephones were largely a commodity, with only premium BlackBerry devices enjoying standout features, dedicated users and the benefits of sunk costs. Apple Computer (now called just Apple) reversed that by adding processing power, expandability (through apps) and exquisite industrial design while charging prices premium even to those of BlackBerry cell phones.

BlackBerry died because indecisive management only began to react to the iPhone after the battle had been lost. A similar fate can befall router vendors. Router makers can revitalize their offerings by re-imagining their products to address the current and future needs of broadcasters and their plants. By doing so, simple-minded COTS switches and their orchestrators can be relegated to the least discriminating facilities with the simplest needs and use cases.

This diagram shows a simplified version of a routing switcher based on burned in field programmable gate arrays (FPGAs) for input processing, switching fabric and clean switching.  (click to enlarge image).

This diagram shows a simplified version of a routing switcher based on burned in field programmable gate arrays (FPGAs) for input processing, switching fabric and clean switching. (click to enlarge image).

Integration, dematerialization and modularity

The electronics learning curve, the basis of Moore’s Law, predicted that prices of transistor cells would decrease on the same time line as the ability to integrate more transistors onto a given piece of silicon real estate. The result has been exponential increases in processing power along with steady decreases in the price of integrated circuits and devices that employ ICs.

Routers have modestly integrated new features over time; principally clean switches and automatic cable equalization. While support for IP interfaces have recently been introduced, changes in media transport and file-based workflows have been largely ignored by router makers, even the mature SMPTE MXF (ST-337) standard. Devices that natively support MXF, or proprietary standards including DNxHD and ProRes, must now be converted to SDI to be routable.

For example, an input of uncompressed HD video could be converted internally for simultaneous output to destinations that require SDI, MXF or other formats. Integrating format conversions and up-, down- and cross-conversions into routers will involve exponential increases in processing power be available within routers. By minimizing conversions, the dematerialization of external processing will improve overall video quality. With enough processing power, uncompressed flows could even be compressed for transmission or streaming.

Figure 3. This example illustrates how a routing switcher could be implemented through the use of multiple GPUs.  (click to enlarge image).

Figure 3. This example illustrates how a routing switcher could be implemented through the use of multiple GPUs. (click to enlarge image).

By employing the latest PCI Express computer bus standard, router busses would benefit from COTS chipsets on their main boards while being able to add processing power from COTS GPU cards. Lashing together GPUs in redundant arrays of GPU cards would enable resources to be directed by the router where and when needed. Figure 3 is a simplified schematic diagram of a routing switcher provisioned by GPUs.

Instead of a forest of unmonitored external processing gear, the routing switcher would monitor status and instantly route around any problems. New functions and features, even Software Defined Networking (SDN) could be added by activating license keys, not installing new proprietary hardware or buying a new frame.

By moving processing power from input and output port interfaces to GPUs, simplified interface cards would transform external SDI or IP flows to or from the form needed for the internal bus. Routers would end up being the smartest gear in the room with processing power to spare.

The power and savings of COTS components can and must be engaged in coming generations of routing switchers to overcome the peril and commoditization threat of network switches. Properly implemented, true digital routers would even provide an easy, in-service upgrade to 4K, 8K or whatever comes in the future.

John Willkie is a former broadcast engineer, systems integrator and now consultant based in San Diego, CA.

John Willkie is a former broadcast engineer, systems integrator and now consultant based in San Diego, CA.

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