SECOND NATIONAL BROADCASTER WITHIN A MONTH CHOOSES CRYSTAL VISION’S NEW ASPECT RATIO CONVERTER (September 2004)

Photo caption: Channel 4's master control room

Crystal Vision’s new aspect ratio converter, ShARC-XP, has been adopted by another of the UK’s major broadcasters. Channel Four has bought two of the boards - which were released in June and offer two horizontal conversions - to support the installation of PixelPower Clarity units for on-air presentation graphics playout. This is the second order for ShARC-XP to come within a month of its release, the first being from the BBC who used ten to broadcast Euro 2004 from Portugal.

Channel Four produces all of its graphics elements in 16:9 to reduce the amount of preparation required to support presentation graphics. When use of Clarity begins in a few months time, ShARC-XP will be needed to match the format of the graphics and the background image when programme material is in 4:3 format. For example, a live background input in 4:3 format would be converted to 16:9 by ShARC-XP as it enters the Clarity unit, to match the graphics output. The combined 16:9 output will then be converted back to 4:3 by the same aspect ratio converter.

ShARC-XP is a 10 bit digital aspect ratio converter. There are both single and dual channel versions, of which Channel Four opted for the latter (ShARC204-XP). It operates in two modes, the first converting a 4:3 picture to 16:9 by compressing the image and adding black bands to the sides so that it can be viewed on a 16:9 monitor without being distorted. The second mode converts signals from 16:9 to 4:3 by horizontally stretching the central 75% of the input picture. There is no vertical processing with ShARC-XP, which means that the vertical performance is not compromised at all and the picture is of exceptionally high quality.

Also part of the same order were four ViViD124 variable video delays which will be used to match the two frame delay caused by Clarity so that when the graphics generator is switched out of the system there will be no jump in timing. ViViD124 gives up to 2.08 seconds delay (52 frames) in 625 line and 2.0 seconds (60 frames) in 525 line. It is ideal for use with virtual studios or with graphics generators such as Clarity because of the delay the technology causes when creating the images.

ShARC-XP and ViViD124 can be controlled from the board edge, by frame active front panel, by remote control panel, GPIs, or using Statesman, Crystal Vision’s PC control software. Channel Four will be controlling both with the use of GPIs, and the boards will be housed in a 2U Indigo 2 frame.

Robert Luggar, Engineering Projects Manager of Channel 4 Television, commented "Both products were selected on the basis of functionality and good value for money. The development of ShARC-XP came at exactly the right time for this project."

Based at Whittlesford near Cambridge in the UK, Crystal Vision provides digital keyers and a full range of digital and analogue interface equipment including converters, decoders, encoders, distribution amplifiers and audio embedders to the professional broadcasting industry worldwide.