Perhaps you’re mature (I’d hate to say “old”) enough to remember presentations in the seventies where the simple touch of a button would execute a smooth dissolve between high-resolution slide graphic and still images. In the mid-eighties, as the Kodak Ektagraphic gave way to the Sony 1040, we relied on the T Bar on production switchers to give us the manually controlled dissolves and wipes we desired between video sources. By the early nineties one or more graphics computers was obligatory for virtually all corporate meetings. Seamlessly switching these sources with video was easily solved by down-converting their close-to-NTSC (640x480 or 800x600) resolutions. (640x480 or 800x600). This worked quite well, provided that thee down-converter operated at the component level to adequately accommodate the chroma bandwidth and to minimize artifacts introduced by the encoded video format.

Enter Microsoft. . .specifically PowerPoint. Almost overnight every business executive and secretary in America became a graphics artist. Folks who could not turn on a slide projector five years prior began making elaborate presentations on their laptops. While trained graphic artists worked creatively within the constraints of the video world, this new army of artists assaulted us with bullet points and complex graphs. They demanded their “artwork” look as good on a twelve-foot screen as it did on their twelve-inch computer monitor. No one wanted their precious images scan converted to work within the video system. Compatibility was losing the war to resolution.

For a short period of time corporate America accepted a screen glitch while the projector locked up to the new scan rate, but the edict was clear. Staging companies, supported by innovative equipment manufacturers, must resolve the seamless switching issue.

Extron came out with their 4LD in 1997. This device doused one video source, switched the sync, then smoothly brought up the second source. Unfortunately this only worked about 80% of the time. Untimely video rolls, glitches, or screen garbage were too often experienced, and the advantage of having converged projectors for increased brightness and redundancy was sacrificed because two projectors seldom handled the switch the same.

Some producers insisted that two projectors be used, not with converged images, but rather one for high scan graphics and one for video. You “dissolved” between the two by turning one on and the other off (or if you were really sophisticated by dousing one and undousing the other). This was surely not the solution.

Others envisioned line doubling as the answer. Unless one of the real pricey ones was used, the line doubler only served to hammer the video. Far from a cure, line doubling was at best a band-aid.

And then there was everyone’s favorite myth, just up-convert the video to match the computer. Yeah right, but alas the myth took a turn toward reality in 1998 with the introduction of Synelac’s Mosaic Processor. Rather than down converting graphic sources in order to seamlessly switch video, using the Mosaic the video WAS up converted to match the highest resolution source, and the resulting output was mapped directly to the projector panels. A consistent picture could now be sent to as many as eight sets of dual stacked screens without the annoyance and danger of projector resizing. As wonderful a step as this was, it did not come without problems. While good for displaying graphics, video sources often displayed significant motion artifacts and jaggy edges. TheIts cost (along with similar products from RGB Spectrum and others) was also quite high.

What was now clear was that seamless switching of multiple scanned rate devices was possible and, perhaps more importantly, desired. Live entertainment and corporate staging events using computer-based signals could now have the same kind of control previously found only in the broadcast suite.

Numerous manufacturers and products have contributed to the speedy evolution of seamless switching. Using Analog Way’s Graphic Switcher, six high scan sources could be faded and mixed with no loss of synchronization. The output rate of the switcher could be user defined (VGA, SVGA, or XGA) to match the native resolution of the projector or to meet or even exceed the resolution of the computers. Adding a couple of video scalers allowed you to mix in a couple of video sources. Along with dissolving, the Graphics Switcher could also cut, fade to black, overlay a title or freeze an image. Position and sizing were addressable too.

Where the Graphics Switcher left off, the Folsom VFC2200 was just getting warmed up. Like the Analog Way unit, the VFC2200 could switch between divergent scan rates, but it included a choice for SXGA output. What this meant was that you could choose the highest available resolution projectors as well as support a higher native rate of computer. The VFC-2200 provided adjustable parameters for each independent source including color space and basic geometry thereby making a smoother interface between the graphical and video sources. Flexible output characteristics accommodated differing projection mediums.
Folsom’s more recent ScreenPro products include eight independent inputs and two built in scalers with motion adaptive de-interlacing and filtering. With automatic input video sync detection and both wipe and dissolve transitions, the ScreenPro integrates the video and graphical world very nicely.

Vista was the first on the market (1999) with seamless transitions to multiple screens. Using their 1603M with Sierra’s CM3 dissolve units, gave us component dissolve capabilities on up to three screens simultaneously. Extron’s Integrated Seamless Switching 408 soon followed.

Mostore recently, multi-screen control systems such as Vista Controls’ ScreenMaster Series have given us control of routing switchers and dissolve systems. The ScreenMaster can simultaneously dissolve between any number of sources, wipe across all screens or curtain wipe from the center to the outside screens. When paired with the Folsom VFC2200 or VFC2200DE, the ScreenMaster can be coupled with either a Sierra Video Systems Tahoe or Extron Crosspoint series high bandwidth router. These components provide the raw materials for a very creative and effective multi-screen event.

Today anything and everything from composite video to 1600x1200 can be switched in their native resolution. The determining factor in the presentation environment is the resolution of the projector since any greater resolution is essentially wasted at that point. Anything less than 768x1024 will probably be unacceptable, so using a high quality video/data projector such as the Digital Projection 7GV or the BARCO ELM R-12 for a 1024x1280 resolution is imperative.

There remain significant challenges. Staging companies and their engineers continue to be confronted with a variety of new analog and digital formats covering the entire spectrum of video, data, graphical, and presentation mediums. Motion artifacts still appear and they’re different for different forms of video. Latency, the delay caused by buffering/interpolation and preserving the detail of the up-converted NTSC video, must also be dealt with. Matching the VFC-2200 output resolution to that of the projector’s resolution eliminates the delay normally associated with the projector’s internal formatter, and setting the output refresh rate of the Folsom to less than 59.94 Hz minimizes delays in the formatter. It should be noted that a delay of two to four fields will still be operativeexists in the up-conversion process, even with the filters turned off (because of the de-interlacing process); therefore, it is essential that additional delay not be introducedadded.

Because digital video is normally a serial operation, avoid it if at all possible. While the digital technologies are a great 'zero loss' transport medium, at the point of collection or presentation any advantages are squarely met by the analog equivalent. For instance, using an Abekas 8150 as a switched source for cameras will add a very noticeable 34 lines to 1 frame of delay required to process the digital signal. Take those camera sources directly in analog format to avoid the delay. Until the PC world includes a digital output as standard on computers, stick with analog on your seamless switching system whenever possible. Perhaps the DV connector will change this.

Much like the old days of multi-image slides, simple cues and sequences are easily programmable and seamless switching of high (and low) resolution sources is now expected. Having a staging partner with extensive experience integrating old and new, analog and digital elements in both live shows and broadcast events is vital to success. Regardless of technical definitions, specifications, and manufacturer claims the real test is the audience's eyes.

Steve Alford is President of Alford Media Services, a nationally respected corporate staging company. Steve has a Degree in Telecommunications from ORU and a Master’s Degree in Industrial Technology from Temple University. Steve is an active member of ICIA and is on the board of directors for numerous organizations including the Video Association of Dallas and the USA Film Festival. Steve can be reached at steve.alford@alfordmedia.com