The growing popularity of high definition television has rapidly become one of the broadcast industry's key drivers. Once viewers have experienced the stunning quality of HD pictures, they will settle for nothing less, and as they migrate to larger and more advanced display screens, their expectations of image quality become even greater.
But from the broadcaster's point of view, conversion of an entire plant to HD remains a relatively expensive proposition. For many facilities, a more gradual transition makes the most financial sense, with certain systems being converted to HD as revenue and profitability levels permit--and upconversion serving as a bridge to the future while allowing HD services to be delivered in the present.
Yet, even if money were no object, the reality is that SD video is going to be around for a very long time. Virtually all video source material created before the past several years is inherently SD, and a significant portion of TV content continues to be produced in SD today. The source material for most HD services will long into the future be a mix of content produced in SD, HD and on motion picture film.
Thus, every TV broadcaster, whatever its financial resources, needs some kind of HD upconversion capability. And all have an incentive to ensure that the pictures it puts out look as good as possible on HDTV screens.
A DIFFERENT APPROACH
When Snell & Wilcox designed Quasar Ph.C, a motion compensated HDTV upconverter, addressing the growing expectations of viewers, the cost to broadcasters of delivering HD services now, and the need for a durable, future-proof solution were foremost among our objectives.
Although upconverters have been around for some time, until now the choice had been limited to expensive and complex units, designed primarily for post-production applications, or lower-cost converters, with output that doesn't always measure up to today's higher picture quality benchmark.
Whether the material is action-packed sporting events or graphics-rich commercials, one of the greatest challenges in HD upconversion is to ensure flawless results regardless of the type of material being processed and the amount and variety of motion it contains. The technical challenge would be daunting enough if all the sources that needed to be upconverted originated as SD video. But in fact the majority of video material to be upconverted is likely to be composed of a mixture of sources such as film (with its 2:3 and 2:2 cadences), mixed film and video, captions, graphics, logos and station branding.
Conventional HD upconverters use either linear or motion adaptive processing techniques, both of which tend to produce visible artifacts. Linear conversion involves processing compromises that can create ringing or softness in the output. Adaptive mode switching causes intermittent loss of clarity and definition, and produces objectionable artifacts on all but the simplest material.
With both of these approaches, the maximum vertical resolution possible with a moving video scene is half the resolution of the input. Unlike traditional upconverters that employ multi-field apertures, Quasar Ph.C's motion compensated conversion delivers sharp HD outputs, regardless of the complexity of the input.
For example, Quasar Ph.C is equally adept both at preserving high-frequency detail in sporting events and at converting the fine detail in scrolling text and captions--even when signals contain a mixture of film and video originated material. This approach guarantees that the resolution of Quasar Ph.C's upconversion output is maximized.
THE POWER OF PPREPROCESSING
In Quasar Ph.C, motion estimation technology is combined with 2:3 pull-down detection based on DEFT technology to handle the tricky issues associated with the upconversion of film originated video and mixed media. Plus, Prefix preprocessing applies a uniquely powerful 3D wavelet-based algorithm to remove noise and other unwanted elements from the signal.
This preprocessing function ensures that, when compressed, Quasar Ph.C's output uses the minimum of valuable bandwidth while retaining maximum fidelity and resolution, which is especially important in applications where the output is fed to a transmission or distribution encoder. It also represents a departure from the compression preprocessors used in conventional HD upconverters, which reduce bandwidth at the expense of picture quality and thus tend to produce outputs that are soft and smeared by comparison.
Finally, Snell & Wilcox FormatFusion technology ensures that each individual element of the picture is processed seamlessly and with precision using the most appropriate conversion algorithm. The result is a clear and sharp HD output regardless of the nature or complexity of the source material.
Additional Quasar Ph.C features include a sophisticated enhancement tool, a gamut legalizer, color space conversion, aspect ratio conversion and closed-caption management that ensures compliance with legal obligations. Quasar Ph.C upconverts 525- and 625-line material to 720p and 1080i. It provides comprehensive audio support including embedded, AES and compressed formats.
Designed for "plug-and-play" applications in live production, playout, and mastering and repurposing, the 1RU appliance offers user-friendly controls. Quasar Ph.C's comprehensive range of image processing functions is accessed via a front panel control display. Its simple navigation aids include color backlights on the LCD, control knobs that enable users to control multi-settings without having to navigate up and down the hierarchy of options and single-level menus.
Quasar Ph.C is designed to give broadcasters a competitive edge by enabling them to produce the consistent, high-quality HD pictures their viewers expect while maintaining a cost-effective transition to HD. Users can continue working in SD, then, as they gradually migrate to full-scale HD operations.
Joe Zaller is the vice president of marketing for Snell & Wilcox.
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