AudioMedia - June 2008 - (Page 56)

video guide A Sound Pro’s Guide To Video HD Acquisition Delving behind the silver screen, KEVIN HILTON takes a look forward to what we can expect of HD’s impact on the industry. ameras have developed over the past years to give cinematographers and operators a broad range of tools for different aspects of film and television production. Although the gaps between camera technologies in the high, mid, and low end markets have contracted in recent times there is still a big demand for high quality cameras and acquisition formats that can rival film and the older style of equipment. High definition is certainly providing that in television, both for live events, sport in particular, when working in interlaced mode, and increasingly for documentaries and drama, which are shot using the progressive format. Due to adjacent lines of a picture being scanned in succession, progressive produces a frame-based look similar to film, which is why high end TV drama producers see it as a viable alternative to Super . For many, and not just traditionalists such as compiles and the older generation of directors of photography, HD does not match the depth and warmth of film. The ideal would be an electronic means of capturing pictures that, like HD, could be connected to a digital intermediate (DI) post-production system so the footage can be worked on and distributed as data but which are more like film than video. This desire has resulted in what is regarded as the next generation of filmmaking device, the digital cinema camera. Huge amounts of money have been spent on research to allow pictures to be recorded as data on tape or hard disk. Major productions are now in progress using this latest technology, but there are still doubts over performance and reliability, giving, for the time being at least, HD a short lead in the race to be the dominant acquisition format of the future. During the late s there were attempts to break the monopoly of film in commercials, music promo, and feature production using the then analogue high definition systems, one of which, somewhat confusingly given the recent development of the lower end digital format for DV tapes, was known as HDV. The two notable films made at the time, Julia and Julia, and Crack In The Mirror, are now merely footnotes in the history of HD. The equipment used to make those films was cumbersome and involved connecting the camera to video recorders in a truck by means of lengths of cable. What filmmakers wanted was a video or other kind of media version of the film camera; self-contained and easy to move. HD camcorders certainly provide that, and while the camcorder may be mostly identified with general TV production and newsgathering, the top-of-the-range models have been designed as modern equivalents of Arri and Panavision cameras. Sony staked its claim with the HDCAM format, with the higher end of the range branded as CineAlta. The first in the series was the HDW-F , which is still the flagship today in the upgraded C SOUND PRO'S VIDEO GLOSSARY Helical scanning During the days of audio tape recording, sound quality could be improved by increasing the speed at which tapes passed over the static record head. For a video device to cope with the huge amount of data needed to accurately capture the picture (and sound), the tape would have to travel at immense speeds if the record head did not move. That is clearly impractical so the helical scanning drum was developed to keep tape speeds at a sensible rate while still being able to pass on all the necessary information. This has been used since the days of earlier analogue video formats, including Beta SP, and is still regarded as an effective method in the digital age. The ½-inch wide HDCAM tape is wrapped around the majority of a cm ( -inch) drum, making contact at one edge and leaving at another. At no point does the tape come in contact with the bottom centre of the outside of the drum. This forms the shape of a helix, hence the name of the system. Because the HDCAM mechanism has four heads the tape is always in contact with two of them; as the heads are turned on and off information is recorded in strips at shallow angles on to the tape. form for the F R. The HDCAM recording system uses the -bit DCT (Discrete Cosine Transform) : : method for a recorded video bit rate of Mbit/s. In HDCAM the picture data being recorded, either progressively or interlaced, is stored on tape with each frame as a separate and individual entity. These are arranged in diagonal strips along the tape and are read using the Helical scanning method (see glossary). To produce a filmic result the F operates at p ( frames a second, progressive), and for greater mobility the R version has a smaller and lighter optical section and recording mechanism. The film and TV production business clearly saw the F as a serious alternative to film cameras, to the point that Panavision produced its own version for the feature market. The ‘Panavised’ F , the HD F, has a : zoom lens and follow focus capability, augmented by a number of hardware additions that are far more familiar to directors of photography who work primarily in film. Panavision added a viewfinder arranged in three sections that attach to the existing support rails. This bracket accommodates either the viewfinder itself or an extension unit for the housing. The lens mount is similar to Panavision’s usual film configuration, only marginally bigger to cope with the : zoom lens that was part of the original re-design, used by George Lucas for the recently made first three instalments of the Star Wars saga. The Panavision lens was originally designed for mm film work, but in a video setting the frame size is two and a half times bigger than the imaging array of the F . Consequently the lens for the HDCAM camcorder had to give a smaller image but be sharper to compensate for the amount of magnification required to project the finished images. A new lens mount and front plate were also needed to support the extra weight of this lens. Lenses produced by Panavision since the launch of the HD F, now augmented by the HD R, have been configured for HD and offer similar resolution. > 56 AUDIO MEDIA JUNE 2008

Table of Contents Feed for the Digital Edition of AudioMedia - June 2008

AudioMedia - June 2008 Contents Recording Post Broadcast AES Review What's Up UK? Geofocus: Australia For the Record Special Report: Videosonics Newstalk: DPA New Microphones Novation SL Compact Allen & Heath IDR-8 Eastwest Quantum Leap SD2 & Goliath Final Cut: Indiana Jones Merging ADR Module Koolworld SSL Duende Good Product Sampler: Microphones Video Guide AMSR Meyer Sound The Blue Planet Live! Royer Labs Mics R-121 & R-122

AudioMedia - June 2008

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