Sony’s XDCAM technology explained

With ever-increasing pressure to produce quality programmes more quickly and at lower cost, broadcasters are on the lookout for a format that can do everything from random access recording and playback of data to advanced metadata handling and storage.

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By  Vijaya Cherian Published  April 7, 2004

I|~|boatb.jpg|~|Shooting with the XDCAM.|~|Historically, video production has been characterised by an evolution of tape formats. With the performance of successive developments dictated by the engineering capabilities of its day, new formats have outperformed their predecessors in terms of key criteria such as picture quality, reliability, recording duration and compactness. This dependence of a format on its physical medium contrasts with the IT world, where file formats are essentially logical entities with little or no connection to a specific storage medium. Sony’s Professional Disc breaks this physical link by offering a format free storage medium that can be used to store, replay and manage audio and video files in various formats as well as metadata, EDL information and files relating to a project. This single sided 23.3 G/bytes optical disc stores up to 85 minutes of broadcast-quality pictures and sound in DVCAM or MPEG IMX formats, and provides Digital betacam picture quality. Measuring 129 x 131 x 9 mm, the disc weighs only 89 g, representing a significant reduction in size and weight compared with other tape-based storage media. Unlike tape, the professional disc can be used to record data 1,000 times. Sony claims that the disc is also capable of resisting physical shocks, vibration, extremes of temperature, magnetic fields and X-rays. While professional video production has been revolutionised over the past few years by the appearance of nonlinear editing systems (NLEs), workflows are still constrained by the need to transfer content acquired using a tape-based camcorder to the editing system. This is typically a real-time process, necessitating expensive facilities time for the transfer of shots from tape to NLE. After ingest of tape-based material to the NLE, further time cost penalties are incurred in selecting shots from many hours worth of material (on a typical shoot) before the serious business of craft editing begins. In contrast, XDCAM allows an operator to review shots while still in the field as thumbnails on the display screen of a camcorder, field player or computer. Clips can then be upload as low bit rate proxies to a laptop PC at up to 50 times faster than real time for browsing, scene selection and rough editing. While not of broadcast quality, these proxies offer sufficient resolution for use on air in “breaking news” situations, eliminating the need to transfer material from camcorder to NLE for editing and playout. While still on location, storyboards and pre-compiled EDLs can be sent from a laptop to the news room or edit suite from anywhere in the world where a broadband network connection is available. Back home, pre-selected full resolution clips can be transferred from the Professional Disc media to an NLE at up to five times normal speed. ||**||II|~||~||~|The XDCAM’s biggest advantage over other tape formats is that each disc costs US$40 — the lowest cost per Gigabyte of any non-linear, removable broadcast media. This media also allows 1000 record/rerecord cycles, which reduces media replacement costs compared with tape. Although even this disc incurs a fair amount of maintenance cost, it still is 50% lower than professional tape based mechanisms in total. There is also a 6000 hr/4000 hr (deck / camcorder) replacement interval for optical block compared with the typical 3000 hr/2000 hr (deck / camcorder) replacement interval for a tape-based mechanism. The capability to select DVCAM or MPEG IMX formats reduces hardware inventory requirements in production and rental operations, which means the user requires only one camcorder/deck needed instead of two. A file oriented, network capability allows pooling of XDCAM equipment in production environment. Typically share one XDCAM deck between three nonlinear editing systems as opposed to traditional requirement of one VTR per NLE. PAL/NTSC capability of the decks eliminates the need for dual equipment to support different broadcast standards. ||**||

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