The evolving master control

Master controls have gone from monolithic boxes to modular, adaptable, scalable mini masters
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TVOntario in Toronto uses Leitch’s Opus master control switcher to operate two broadcast networks. The single user interface controls multiple station outputs, which is key to signal consistency.

Blame it on branding, the use of those ubiquitous logos that appear in the corner of the TV screen. At first, these logos just winked on and off after each break. A year later, they stayed throughout the entire program. Now, they've become a mainstay, including everything from station IDs to promos for future programming and election results. This branding improves our viewing experience by helping us navigate through today's sea of entertainment alternatives.

Branding is the logical outgrowth of a broadcast channel's quest for a unique identity and increased viewership. As broadcasters continue to look for creative ways to generate more revenue by repurposing content, it's ironic that something so small has become such an important (and effective) tool. Cable networks can produce new channels almost overnight, all tightly packaged and branded for our enjoyment. The model works well.

Traditional and contemporary models

But branding places new demands on master control. Simulcasting analog and DTV channels (with commercial inserts) is complex enough, even without considering brand content or data services.

Things were simple when we transmitted single analog channels. As the cornerstone of a station's infrastructure, the master control switcher was (and, in many cases, still is) a dedicated box with dedicated inputs and a minimum number of capabilities. (See Figure 1 on page 32.) If a broadcaster required another output channel, he had to buy another switcher — simple, but expensive.


Figure 1. In traditional master control architecture, equipment is more dedicated and overall functionality is less scalable and modular than contemporary designs. Click here to see an enlarged diagram.

Yet, as multichannel transmissions have blossomed, the stress on master control has increased. New capabilities such as automation, character generation and squeeze effects were added around the switcher, but were not typically integrated. The trend toward more informative on-air images has added additional pressure, as master control systems must now handle increasingly diverse, localized branding and data services.

Many broadcast facilities have cutting-edge support for DTV, but their master controls are still years behind. If your switcher is a 15-year-old beast, today's multichannel commercial insertion and branding requirements have likely overstressed it. And facilities that haven't upgraded within the last three years are probably adding functionality as peripheral equipment.

Once a station decides to update its master control, the engineering staff is often surprised to learn that a new generation of master control devices not only provides the necessary staples, but also enables new channels and capabilities to be added economically. In basic terms, master control has gone modular. (See Figure 2.)

The new mini masters

Because of broadcasters' continuing need to realize more value through upgraded channels and services (all within budget), facilities are starting to deploy a new generation of low-cost, modular master control solutions. These “mini” masters are more flexible than their monolithic predecessors. New channels and capabilities such as branding and surround sound can be added with ease. A facility can start with a single SD channel with a minimum feature set and upgrade to HD and more advanced features without purchasing new frames or panels.


Figure 2. A contemporary master control architecture based on a modular platform is flexible and scales well to emerging requirements, enabling users to repurpose modules as required. Click here to see an enlarged diagram.

Scalability, which is becoming commonplace for server and router manufacturers, is being applied to master control. An entry-level mini master might include a spartan yet highly capable feature set comprised of basic transitions and a single SD output. This unit can then upgrade to features such as clean commercial insertion (with effects), Dolby 5.1 mixing, and DVR capabilities for localization and time delay — for both SD and HD. (See Figure 3)

These upgrade modules for logo insertion, character generation, emergency alert, upconversion, voice-over mixing and squeeze effects are not specific to master control, but are, in fact, the same modules used throughout the facility — allowing the facility to leverage them across many applications. Processes that were typically performed upstream have now become native capabilities with one controlling interface.

From the customer's point of view, upconverting an SD signal is the first logical step in unveiling a new HD channel. Using the mini-master concept, the facility can budget for a fully branded SD channel today and reuse the base switching and branding functionality when the time comes to broadcast natively in HD with surround sound. This would not be possible if new frames, power supplies and interconnects were required. Within this model, incremental growth is easy and cost-effective.


Figure 3.This is a detailed functional view of a channel branding and switching module. This module provides the cornerstone of mini master capability, including A/V branding, CG and switching. Click here to see an enlarged diagram.

Next-generation automation systems are already multichannel-aware. In addition to controlling legacy devices, the automation system's timeline controls multiple server channels and master control switcher crosspoints, as well as transitions and branding. If some or all of these capabilities are integral to the master control switcher, complexity is greatly reduced.

The master control operator's task is also easier with today's advancements and, in most cases, the job entails more monitoring than control. Where control is required, new advancements in panel architecture are reducing complexity and providing operators with more flexibility to tailor interfaces to specific applications. Some manufacturers offer a range of panels, from traditional hardware panels to software-based GUI panels that can be customized for specific workflows.

Because of this increased scalability and modularity, broadcast facilities are now solving problems within master control that have historically been difficult to solve anywhere else in the transmission chain. But new challenges are looming, based in part on the rapid evolution of audio, video and metadata.

Today's master control is almost entirely AES-capable, but the concern will be the proper handling of HD and Dolby 5.1 within this environment. Multichannel 5.1 audio for transmission is becoming a de facto requirement with broadcasters who are now designing infrastructures based almost entirely on DTV with surround sound capability.

Challenges on the horizon

With high-definition, surround-capable home theater systems being offered at incredible price/performance points, consumers are forcing broadcasters to get much better at what they do — particularly with regard to audio and video quality.

Another ongoing challenge is maintaining synchronization between video and audio signals throughout the facility. Transcoding Dolby E at various points creates frame delays. Enabling and bypassing video processes upstream creates additional delays. Using frame synchronizers at specific points can resynchronize these signals, but each path change adds complexity. Here, broadcasters are demanding automated, content-aware solutions that use metadata to correct for these issues seamlessly at master control.

Another issue of emerging importance is conformance monitoring, an area where master control has the potential to offer an elegant solution. Within an increasingly complex mix of daily content, the facility must verify that it is playing all programming as planned and on schedule.

Watermarking and metadata technologies can offer potential solutions, and with the modular integration capabilities of today's master control, manufacturers can offer these features as future scalable enhancements.

There are several important factors to consider when selecting a new master control switcher:

  • Consider a solution with an internal, self-contained routing matrix for seamless A/B mixing. The matrix lowers the reliance on the house router, and the modular framework allows for additional input blades. Conversely, if cost is an issue, marrying a simple A/B master control to the house router is effective.
  • Select a solution that offers a choice of panels. The ability to configure a panel for a particular event or application has many advantages.
  • Consider a company whose switching fabric is deterministic, with the ability to guarantee a transition in a precise amount of time — regardless of network traffic. When automation instructs the system to perform a task, ensure that the latency is within acceptable limits or fixed within a deterministic number of frames. Your LAN's IP traffic should not be a gating item.
  • Look closely at the company's modular direction, and its ability to leverage its core technology across applications. An excellent example is time delay, which is an important requirement when planning for multiple-time-zone broadcasts. Exploiting the modular concept shouldn't require an entire server, but rather a single plug-in storage or time-delay module.

Master checklist

Master control switchers are now available in a variety of economical, scalable configurations, all targeted at making it easier for broadcasters to repurpose content, create new channels, brand their output and generate more revenue with existing assets. This à la carte solution eases the visual and financial requirements for getting a new channel to air. The continuing modular trend also makes sense given today's economies of scale. On a budget slated for improvements only, a large master control switcher would be out of the question. However, additional channels or plug-in capabilities for an existing mini master would likely be right in line.

The big-city station has different needs than the country station. The new wave of mini masters provides the flexibility to create a unique on-air look on a limited budget, with the potential to upgrade as required.

Master control à la carte

Steve Sulte leads Leitch's chief technology officers' group. Eric Goodmurphy is a product manager for master control switchers and development at Leitch Technology.