WirelessHD (WiHD) An industry-led effort to define a specification for the next generation wireless digital network interface for wireless high-definition signal transmission for consumer electronic products. The WirelessHD specification is based on a 7 GHz channel in the 60 GHz Extremely High Frequency radio band. It allows for uncompressed digital transmission of high-definition video and audio and data signals, essentially making it equivalent of a wireless HDMI.

WM9 and WMV See: VC-1

Word clock Clock information associated with AES/EBU digital audio channels. Synchronous audio sampled at 48 kHz is most commonly used in TV. The clock is needed to synchronize the audio data so it can be read. See also: AES/EBU audio

Workflow Literally, the flow of work. The wide-scale adoption of digital technology in the production chain of television and media in general has produced many possibilities for arranging exactly where and in what order the various required steps are done. This can be one of the big advantages of ‘digital’. In many cases this does not follow the traditional analog path where there were few, if any, choices. Today there are any number of ways to arrange workflows but only the good ones will offer the most efficient and fast way of achieving results. Important elements are ensuring there are no bottlenecks – powerful enough processing to achieve fast results and fast connections to make sure data is available where and when you want it. Often the better workflows involve less movement of data as more tasks are completed in one area. Workflow patterns are altered by technology. For example, traditional film grading is completed prior to editing and any visual effects work. Today it is possible to edit a digital film and then grade while seeing the material in context.

WORM Write Once/Read Many – describes storage devices on which data, once written, cannot be erased or re-written. This applies to some optical disks that offer high recording densities and are removable, making them very useful for archiving. CD-R and DVD-R are examples. See also: Optical disks

WYSIWYG What You See Is What You Get. Usually, but not always, referring to the accuracy of a screen display in showing how the final result will look. See also: Color Management

XDCAM

Sony camcorder products that use its Professional Disc (PD) technology, an application of Blu-ray Disc, as the recording medium. The product range includes camcorders, mobile and studio decks which are designed to take advantage of the size, weight, data speed and re-record features of the PD technology. See also: Professional Disc

X´Y´Z´ A mathematically defined absolute color space, CIE X´Y´Z´, also known as CIE 1931 color space, was created by the International Commission on Illumination (CIE) in 1931. It was not heard much of in the digital media industry until X´Y´Z´was selected by DCI as the color space for digital cinema.

This Glossary has been produced with special thanks to Quantel and the many contributors and commentators from the industry around the world who helped create The Digital Fact Book.

Quantel’s complete 20th Anniversary edition can be downloaded from www.quantel.com

We would welcome any comments, suggestions or additions. Please send them to glossary@thegma.eu

Y, Cr, Cb

The digital luminance and color difference signals in ITU-R BT.601 coding. The Y luminance signal is sampled at l3.5 MHz and the two color difference signals are sampled at 6.75 MHz co-sited with one of the luminance samples. Cris the digitized version of the analog component (R- Y), likewise Cb is the digitized version of (B-Y). For the HD SMPTE 274M standard, sampling rates are 5.5 times greater – 74.25 MHz for Y and 37.125 MHz for Cr and Cb.

Y, R-Y, B-Y

These are the analog luminance, Y, and color difference signals (R-Y) and (B-Y) of component video. Y is pure luminance information whilst the two color difference signals together provide the color information. The latter are the difference between a color and luminance: red – luminance and blue – luminance. The signals are derived from the original RGB source (e.g. a camera or telecine). The Y, (R-Y), (B-Y) signals are fundamental to much of television. For example in ITU-R BT.601 it is these signals that are digitized to make 4:2:2 component digital video, in the PAL and NTSC TV systems they are used to generate the final composite coded signal and in DTV they are sampled to create the MPEG-2 video bitstream. See also: 4:2:2, Luminance, NTSC, Y,Cr,Cb, YUV

YUV

Convenient shorthand commonly – but incorrectly – used to describe the analog luminance and color difference signals in component video systems. Y is correct for luminance but U and V are, in fact, the two subcarrier modulation axes used in the PAL color coding system. Scaled and filtered versions of the B-Y and R-Y color difference signals are used to modulate the PAL subcarrier in the U and V axes respectively. See also: PAL

Zits

Spots that occasionally appeared on the faces of picture tubes showing digital pictures when the technology was in its youth. These were caused by technical limitations but now that designs have matured, today zits only now appear during fault conditions.

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GLOSSARY OF TERMS