While scan converters of past focused on taking the video graphics array (VGA) from computers with resolutions of 640 x 480 or 1024 x 768, today’s converters have to be flexible to accommodate multiple signal forms.
by J.J. Smith
Scan converters have been traditionally used to takes a high-resolution computer signal and convert it all the way down to a standard definition video rate, said Jim Scrivner, who is the manager of product marketing for Extron Electronics. “That’s the origin of scan converters, but as the industry has evolved, it’s (now) more of a loose reference,” he said.
Extron Electronics’ USP 507
SCANNING MULTIPLE FORMATS
“Back in the hey day, a scan converter was used primarily from taking content from the VGA (video graphics array) types of computers with 640 x 480, 1024 x 768 resolutions being the highest resolutions that we had to deal with,” Scrivner said. “Those were coming in from RGB and HV (home video) analog video, and the areas of use are still the same, but there is also the added challenge of video formats with the DVI (digital visual interface) or DHMI (high definition media interface),” he said. “So a scan converter today should be flexible enough to accommodate both analog and digital signal formats, at a high-resolution standpoint,” he said.
RGB Spectrum’s Video Link 1690
A converter that Scrivner says is flexible is Extron’s USP 507. The unique aspect is the “U” part of that scan converter, which is meant to describe “universal” and USP stands for “universal signal processor,” he said. USP 507 has a variety of inputs on the device making it “a one-box solution” for a users’ digital and analog video conversion needs. It provides high performance video scaling, transcoding, as well as analog-to-digital and digital-to-analog conversion in a single product. An integrated seven-input switcher supports all common analog and digital video formats. The USP 507 is the ideal solution for meeting the challenge of integrating digital and analog video sources within a single system design.
In addition, the USP 507 should be of interest to government broadcasters because they tend to air content such as PowerPoint slides that likely originated from a high-resolution source, but was converted to video for the broadcast, Scivner said. Those broadcasters also tend to have archives full of analog material, he said.
Converting archived material, as well as new material, “into a true video signal” is why scan converters exist, said Francesco Scartozzi, Matrox Electronic Systems Ltd.’s director of sales for the Americas. Such scan converters are used by public, education and government (PEG) channel broadcasters to get computer-based graphics out as a high-quality video signal, he said.
The product Matrox Electronic Systems offers to help them do that is the Matrox Convert DVI Plus. It is an HD-SDI scan converter with genlock and region-of-interest support. It enables broadcasters to easily and economically take computer-based content—that is quickly becoming a key part of broadcasts—to the air. “All users need is a computer… the unit attaches to the DVI signal out of the computer, and you feed it into the box,” Scartozzi said.
Matrox Electronic System’s Matrox Convert DVI Plus
In addition, the unit creates broadcast video from computer applications such as Skype, YouTube, Google Earth, video games, and web browser sessions, as well as mobile phone videos. However, the images on websites, they are not video signals, they are not the same frame rate, they are not the same resolution, so scan converters exist because they turn what is seen on computer screens into true video.
BECOMING A NICHE PRODUCT
However, there are scan converters producers who say those converters are quickly becoming a niche product because most content produced today is already in a digital format. The organizations using scan converters are not using them as “the classic old fashion scan converters” where computer content is converted to an analog format for broadcast, said Tony Spica, the vice president of sales for RGB Spectrum. Material is being produced and broadcast in digital formats, therefore eliminating the need for a scan converter, he said.
Nonetheless, RGB Spectrum still producers scan converters, Spica said. “We still make a classic scan converter for the broadcast departments of government agencies because in the government there is a lot of legacy material that they might want to put on air, so they still have the need for the older type of scan converters,” he said. That converter is the Video Link 1690, which offers NTSC/PAL composite video, S-Video (S-VHS, Hi-8) and component analog video (Betacam/MII) outputs. SMPTE 259M digital output is available as an option. State-of-the-art digital signal processing circuitry eliminates interlace flicker in the output image. Even thin horizontal lines appear stable. Multiple levels of filtering offer users the best choice between image sharpness and flicker elimination. A zoom function lets users scale a portion of the image to emphasize or to provide just the right amount of underscan/overscan adjustment. The RGB/Videolink 1690 provides automatic synchronization to computer signals at up to 1600 x 1200 pixels, including virtually all desktop computers and workstations.