The Digital Fact Book - Quantel

Purpose-built hardwareHardware and software built for a specific task (e.g. a DVE), not general purpose (computer).Purpose-built hardware is able to provide much improved processing speeds, between 10and 100 fold, oversystems using the same technology applied to general-purpose architectureand operating system software. This becomes important in image processing where tasksrequire a great deal of power, especially as the demands increase in proportion to the picturesize – significant for working with HDTV and digital film.However, as standard/general-purpose platforms continue to become ever more powerful,so it can make sense to swap out some purpose-built hardware, which tends to be morecostly, for software solutions. This ability to swap is a part of Quantel’s generationQarchitecture. Another approach is to use some new specialist GPUs to provide acceleratedimage processing.QuantelApt name for the world leaders in digital television equipment – abbreviated from QUANtizedTELevision. Quantel has 35 years’ experience of digital television techniques – significantlymore than any other manufacturer.QuantizationFactor applied to DCT coefficients as a part of the process of achieving a required videocompression. The coefficients relating to the least noticeable aspects of picture detail– e.g. high frequencies with low amplitude – are progressively reduced so that the final datawill fit into the specified data file space. This space is often fixed and relates directly tothe quoted compression ratio for I-frame only schemes such as DV. Note that the requiredquantization will vary according to scene content. Given that too much data would causeproblems by overflowing the allotted capacity of the file, compression schemes arecautious and designed to undershoot the file limit. To what extent the files are filled is ameasure of the quality of a compression scheme – a reason why the quoted ‘compressionratio’ does not tell the whole story.PQQuantizingThe process of sampling an analog waveform to provide packets of digital informationto represent the original analog signal.See also: Into digits (Tutorial 1)QuickTimeQuickTime is a multimedia framework developed by Apple Inc. capable of handling variousformats of digital video, media clips, sound, text, animation, music, and several typesof interactive panoramic images. Running on either OSX or Windows operating systems,QuickTime supports software packages including iTunes, QuickTime Player and Safari.143