Software Field Monitors, Part 1

Divergent Media ScopeBox 2.0

One of the coolest product categories in the HDV@Work space is software programs that provide video scopes, a large preview monitor, direct-to-disc recording capabilities (DDR), and other features. In this issue, I'll introduce you to the category of products and illustrate and explain some of their benefits. Next issue, I'll look at two of the more prominent products in the category: Adobe OnLocation CS3 and Divergent Media ScopeBox 2.0.

By way of background, to run these programs, you connect your camcorder to your computer via your FireWire port and click your camcorder into recording mode. Once the video starts previewing in your viewfinder, it gets transferred through the FireWire connection to your computer, where these programs analyze the incoming stream, displaying a preview window, various scopes, and other data on your computer screen.

The biggest problem these programs help solve relates to tuning your cameras for optimal exposure. Back in the day, where shooting high-quality video required a $25,000 camera and a budget to match, most videographers lugged various scopes around to ensure proper exposure and also to ensure proper white balancing.

The democratization of video production, delivered courtesy of the DV camcorder, didn't eliminate the problem, but few of the new class of producers could afford this equipment. So most of us either shot in automatic exposure mode or tried using zebra stripes to set exposure. Unfortunately, zebra stripes are a blunt instrument when it comes to fine-tuning exposure settings—especially when viewed in a 2.5in.-or-smaller LCD preview screen. So the biggest problem these programs solve is to deliver scopes on location (assuming that you have a notebook computer, of course).

Figure 1. Man, white-balance card, Waveform Monitor, and Automated Quality Monitor.
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If you've never worked with a waveform monitor, it's almost impossible to grasp how significant this truly is. So let's take a step back and discuss what a waveform monitor is and how it works. Have a look at Figure 1.

This is a screenshot of OnLocation showing a video of my buddy Gary holding a white-balance card. The Waveform Monitor is on the upper right, while the Automated Quality Monitor, which I'll discuss in the next issue, is on the lower right.

Briefly, the Waveform Monitor displays the light in the scene in waveform mode so you can analyze lighting intensity. Levels are represented in IRE values (for Institute of Radio Engineers, go figure) and shouldn't exceed 100, which is pure white, or fall beneath 7.5, which is pure black. If the signal exceeds these values, the camera simply captures all white or all black in the effected pixels, essentially losing the detail in those pixels.

Note that the horizontal position on the Waveform tracks the horizontal location in the video frame, so the wide, flat area you see on top of the waveform shows the value of the white-balance card that Gary is holding. The IRE values for the white balance card are above 100 IRE, which isn't a problem because I'll remove the card before shooting for real. But, if I shot as is, the text you can see on the card would likely disappear in the captured video, turned pure white by the excessive light.

On the other hand, Gary's face is around 65 IRE, which is too low for a Caucasian face—I'd want those levels to be around 75. In addition, because the values at the bottom of the waveform—which represent the black curtain—are hovering above 7.5 IRE, if I shoot as is, the curtain may appear faded. The clear message is to reduce lights on the background and boost lights on the face (and don't let Gary wear a white shirt), which is a whole lot more data then I'd get from zebra stripes set at 100 IRE or 75 IRE.

Figure 2. Vectorscope, RGB Parade and Luma Histogram.
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Let's look at a three more scopes that many shooters also like to have at their disposal to help fine tune their image. Note that I've changed programs and images for Figure 2, now showing ScopeBox shooting the Cambelle's test image from DSC Labs.

The Luma Histogram, shown on the top left, shows the same information as the Waveform Monitor, but in a different way. Specifically, it also shows brightness values (also called luminance, hence the Luma in the name), but on a scale of 0 to 255, with 0 being complete black on the left, and 255 being complete white on the right. Rather than showing the location of the pixel in the frame, the histogram shows the number of pixels at each value. For example, the two peaks in the figure are probably the models' dark hair (on the left) and the blue sky on the right.

What this chart tells me is that the luminance values are grouped around the middle, which usually means that the picture will lack contrast. This is to be expected in a picture on a wall lit by fluorescent lights; in the real world, I'd shift the lights around to create darker and brighter regions.

If changing the lights didn't produce the desired results, I'd also mess with the Canon XH A1's custom settings, such as the black stretch, knee, and pedestal controls. Having the detailed and immediate feedback from the histogram and waveform, as well as a 17in. preview screen, courtesy of my MacBook Pro, gives me a lot of confidence to experiment that I don't have when I'm relying solely upon my LCD preview screen.

The other two scopes, RGB Parade and Vectorscope, help producers check color values in their signal. I tend not to use these scopes, and just wanted to let you know that they are typically available in this class of product. Wikipedia has great descriptions for both scopes, so if you need more information, check www.wikipedia.org.

Figure 3. OnLocation's Audio Spectrum Analyzer.
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In addition to these video scopes, most products in this class also offer audio analysis tools such as OnLocation's Audio Spectrum Analyzer. This measures the input of 32 bands of audio, which is great when you're recording musical events and want to make sure that your microphones are capturing both the bass player and flute. As you can see, there's also a master volume meter and clipping indicator that quickly let you know that your overall are too high.

Figure 4. ScopeBox's preview and overlay controls.
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Beyond the video and audio scopes, having a big screen preview available during the shoot provides several key benefits, some of which you can see in Figure 4, which shows ScopeBox's preview monitor and all available overlays and adjustments to that monitor on the right. I'm a big rule-of-thirds guy, and I mourn the loss of the tic tac toe overlay in most modern camcorders (including the XH A1).

In an interview setting where the subject will be relatively still, you can use these guides to help align your framing, and the larger preview window to fine tune your focus. On the other hand, when shooting in HDV on even a powerful desktop such as the dual-processor, dual-core Intel Xeon Mac Pro I work on, there's a noticeable delay between when you position the camera and when the computer LCD panel updates. This latency will prevent you from using the monitor to frame or focus on fast-moving subjects—say, in a concert or other live-performance environment.

As you can see on the bottom right of ScopeBox's overlay control panel, you can also display Luma and Chroma Zebra stripes, which mimic your camcorder's display and provide a nice adjunct to the data coming in from the scopes. With ScopeBox, you can also add a graphic in the preview—say, to simulate the appearance of a lower-third title.

If you compare the Cambelles in Figure 4 with those in Figure 2, you'll notice that the contrast is much greater. Unfortunately, this doesn't relate to my black stretch, knee, and pedestal adjustments—it was more the adjustments to saturation, brightness, and contrast in the Monitor Calibration controls shown on the right (note to self; ask Canon why they don't just use saturation, brightness, and contrast controls in their camcorders rather than knee, black stretch, and pedestal).

If I captured the video using the current settings, the captured video would obviously still look faded. Obtaining an accurate preview is a challenge with any preview monitor, so you should calibrate your video monitor beforehand to make sure it's accurate. It's also valuable to check the actual captured video against a screenshot of the preview video to make sure that they're close in brightness and color.

The final major benefit these products deliver is the ability to record directly to your computer while shooting. Not only does this allow immediate playback of the file while on location, it also speeds editing since your clips are already digitized.

OK, that's the general functionality of these classes of products; in the next issue of HDV@Work, I'll detail the workflow and features of OnLocation and ScopeBox.