Computer-based content is now an integral part of daily life. YouTube, Skype, Google Earth, and countless other websites and Web services contain relevant, up-to-the minute, often exclusive video clips, photos and other images. Broadcasters would like to enrich their programming with such material but are unsure how. The brute force method would be to shoot the computer screen directly with a camera, but this technique compromises image quality. An alternative would be to use a typical HD-SDI scan converter with genlock, but this approach can cost thousands of dollars, and often requires a separate audio embedder.
At a fraction of the usual cost, Matrox offers an innovative new scan converter, Matrox Convert DVI Plus. It takes in the DVI-D output of a computer's video card, or any progressive digital video signal, up to 1920 × 1200 pixels, and converts it simultaneously to digital SDI and analog component, composite or S-video outputs, with the computer's audio embedded directly into the SDI stream. Stereo RCA outputs enable use of analog audio with the analog video formats. The unit can be genlocked internally, thanks to a time-based corrector, or externally to an SD analog black burst bi-level or HD tri-level genlock source.
Region-of-interest support is among the most advanced features of the scan converter. This feature allows the user to select just a portion of the on-screen content for output. By simply dragging the mouse, rather than fiddling with buttons on the unit itself, the user can draw the region of interest directly onto the content. The broadcast thus can include a YouTube video or a Skype conversation without showing the entire webpage or user interface, and the unit's integrated hardware scaler can resize the selected area of content to fit the entire screen. Keyboard shortcuts for the region of interest, presets for the output resolution and genlock settings can be saved for future use, saving users time in taking this content to air.
The Convert DVI Plus is uniquely easy to operate via a live preview window in its GUI, which can replace an expensive external SDI preview monitor. Because the operator sees exactly what is being broadcast on all outputs, the content can be easily scaled and positioned to appear exactly where it is desired in the broadcast. A colored background can be used in conjunction with the scaled video for downstream keying applications such as providing over-the-shoulder shots for news programs and lower-third graphics or score tickers for sports broadcasts.
Focus on quality
The scan converter offers a variety of built-in features that aid the user in getting the best output possible for any computer-based content. Full proc amp controls allow for calibration of color and brightness levels on all outputs, and the system automatically applies proper color space conversion from RGB to YUV. In addition to providing anamorphic, letterbox, pillarbox and centercut presets, the system offers aspect ratio conversion to compensate for the fact that computer pixels are square whereas SD broadcast pixels are rectangular. An anti-flicker filter reduces artifacts that result from converting progressive images to interlaced video, resulting in a more stable output. To handle content transitions seamlessly, the operator can use the system's freeze feature to freeze the output, make changes to the content and then unfreeze the output. The control panel can be locked and password protected by an administrator to prevent accidental modifications or tampering.
Operators control and configure the scan converter using a PC-based user interface via USB connection on systems running Windows XP, Windows Vista and Windows 7. Mac drivers are also available for Mac OSX Snow Leopard and Lion. Once configured, the unit can be programmed to behave as a stand-alone appliance. The system maintains configuration information even when turned off and the control computer is disconnected. In stand-alone mode, any DVI device, such as a medical or industrial camera, or another computer, can be used as the input. A rack-mount kit allows users to secure up to two units in 1RU.
Controlling equipment costs and minimizing the need for expensive staff training, while providing high-quality programming, is the job of every broadcast engineer. Matrox scan converters are being used in broadcast operations across the globe to assist in achieving that goal.
Charles P. Amyot is product manager for Matrox Video Products Group.
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