Test, QC & Monitoring Global Viewpoint – November 2017

When T&M Becomes TMI

Broadcast engineers don’t control program content, but they are in near total control how content looks and sounds. Even the most expert golden eyes and ears in the industry demand calibrated tools to objectively visualize the technical elements of program content.

Behind the scenes in TV broadcasting, the seriousness of a production is proportional to the time and expenses invested, and money collected. At the personal level, every frame of every production is serious, if you want to be invited back. A technical TV job is an everyday audition and IQ test. When someone else is paying for the show to go on, all must be perfect all the time, every time.

Engineers ensure technical perfection with waveform monitors, which are designed specifically for TV engineers. Non-engineer operators can be overwhelmed the complication to use one.Every production person with access to the handles to control the technical properties of the content needs a calibrated tool to visualize it. The waveform monitor is the one and only solution, and it requires skill to interpret the information it displays.

Sometimes overwhelming

Most new stand-alone or rasterizer video waveform monitors can display objective measurements of nearly every technical aspect of a digital video signal or signals. Most sell from about $6,000 to about $35,000 with options and accessories. The more expensive models can tell a maintenance engineer everything that can be objectively measured in a SDI signal. The most popular new waveform monitors sell for about $8000.

On the other hand, not everyone can afford a $8,000 ‘scope. The least expensive name-brand waveform monitor costs more than a NewTek TriCaster Mini HD-4, which happens to include a built-in waveform monitor. More about the NewTek Mini in a moment.

Nothing beats a simple, dedicated waveform monitor to monitor, analyze and adjust video signal levels, even at knee level.

Nothing beats a simple, dedicated waveform monitor to monitor, analyze and adjust video signal levels, even at knee level.

Not every operator and position need every bell, whistle and scientific function today’s most popular waveform monitors have to offer. In fact, today’s broadcast-level waveform monitors are inherently over complicated. To most non-engineering operators, nearly everything about sophisticated waveform monitors is superfluous interference. Sometimes, a simple speedometer and knowing how to interpret it is all an operator needs.

Front-line operators don’t need sophisticated functions or a detailed graticule. They’re monitoring the same information pre-color TV engineers used to adjust gain and pedestal in the 1940s: Ensuring the blackest of blacks and brightest of whites aren’t overly compressed. Today, black and white video is known as the luminance signal. Video gain and pedestal are impossible to accurately set without using a waveform monitor to visualize boundaries.

In analog TV, IRE units represent the levels of Analog video, with zero being black and 100 being as bright as white can get within the 1 volt peak-to-peak video signal standard. In fact, analog TV needed setup, also known as pedestal, to compensate for the gamma of old CRTs and image pick-up tubes.

Setup partitions off 7.5% of the brightness voltage range available for content. The interesting thing about analog TV is that the number of possible video content voltages in the 7.5 IRE to 100 IRE range is infinite. Today that number is defined by bits, and pedestal is no longer a necessary requirement.

Using every bit

What makes a good signal stand out today is when every digital bit is put to its best use. Because good content is in the eye of its creator, not every frame of video needs to fill the full range window from black to white. Some scenes, such as one purposely shot in fog, should not fill the entire range. That decision is a creative choice. Sparkle is what happens when every bit is purposely used to create the image.

Ultimately, content ends up in the hands of operators in the process of production and distribution. Most operators assume the creator of pre-recorded content paid attention to waveform monitors and vectorscopes. Experience reveals that’s not necessarily always the case. That’s why control rooms have controls that need a waveform monitor to properly adjust.

The key feature for most waveform monitoring is simplicity. A video waveform is what a camera operator or camera shader uses to adjust a lens iris. It can also be useful to help light a set. Most professional and broadcast cameras come with a built-in waveform monitor feature. Some are better than others, and most are minimal but serve quite well for simply adjusting the iris. When adjusting a camera iris or video level, what’s most important is that the device retains its full dynamic range and whites or blacks aren’t compressed unless they need to be.

Waveform interpretation

Most broadcast waveform monitors are useful for monitoring and maintenance troubleshooting. Typically, operators need the ability to monitor levels and adjust when necessary. All one needs to know about level adjustment is how to interpret a waveform. Here’s how: If the waveform is compressed at the top graticule, it’s too bright. If it’s compressed at the bottom graticule, it needs more setup. Anything more is too much information (TMI) for the task.

Once an operator learns how to filter the front-end TMI, reading a waveform monitor is easy. A hands-on, off-line demonstration can teach an operator what to watch for on the waveform monitor, and what the results look like on a TV display. Level issues are much easier to identify and compensate for with a waveform monitor than a subjective TV display. A waveform monitor is objective and neutral, without content distractions.

Just the facts

Some production work, my own included, generates just enough revenue to pay for minimal production gear and expenses. There’s nothing to spend on T&M gear, and not much need except for camera and imported clip shading.

The built-in waveform monitor in the NewTek TriCaster Mini HD-4 displayed too much information and was difficult to read at a glance.

The built-in waveform monitor in the NewTek TriCaster Mini HD-4 displayed too much information and was difficult to read at a glance.

Our NewTek TriCaster Mini HD-4 came with a built-in but frustrating waveform monitor that is over complicated and difficult to see and read. My solution was to buy a couple of excellent used Tektronix waveform monitors (one a spare) through eBay for $250 and a Kanex Pro HDMI-to-composite converter for $69. The result is a traditional baseband video waveform display of the TriCaster’s HDMI output for about $200. It brightly displays all the setup and level information we need for live, outdoor multi-camera and imported clip shading for HDTV productions, with zero TMI.

Several new, low TMI, basic waveform monitoring products are available today for under $1000. One is the rack-mounted Blackmagic Design SmartScope Duo. A similarly priced “Top Seller” on the B&H website is a camera-top monitor with built-in waveform monitor functions. Another budget-priced solution is the TVLogic Viewfinder Monitor. When the job is to monitor, adjust and set iris and video gain correctly, all you need are the relevant facts that most basic waveform monitors display. Everything else is an operator distraction.

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