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Portable HD storage

Aug 1, 2009 12:00 PM, By David Austerberry

Many alternatives to videotape exist, with price points for every budget.

    

High-quality capture

Many of the portable formats designed for use in camcorders use long-GOP compression for HD to reach the low data rates that can be continuously written to current Flash memory technology. The P2 card uses striped memory modules to reach 100Mb/s data rates, sufficient to support I-frame encoding of HD.

If you want to shoot 4:2:2 or 4:4:4, with minimal compression, possibly at 10-bit resolution, the benchmark is the HDCAM-SR, with a record data rate of 880Mb/s in the high-speed mode. The alternative to a tethered VTR is to use a portable hard drive array. Several manufacturers supply such systems for the digital cinematography market. Such units may be DC powered, with the ability to record dual link HD-SDI as well as 4K signals via an optical connector. The drives are encased in rugged caddies and can be delivered to post in much the same way as a videotape.

Which medium is best?

Each recording technology has pros and cons. (See Table 1.) Solid-state cards and drives are rugged and shockproof, but currently are expensive. They are best suited to use as a temporary cache, rather than an archive format. Optical disks are low cost and can be used for the long-term archive of a production. Hard drives are low cost, but not ideal for use as a permanent archive (more than five years).

Other considerations relate to workflow. What equipment do you need to preview rushes? If you need to archive expensive cards for reuse, what is needed at the shoot to perform the backup? What about copies for escrow to meet the requirements of production insurance?

What may be the optimum medium for news acquisition is not necessarily best for a drama shoot. Tapeless recording presents a wide choice, with price points for every budget.

Table 1. A comparison of tapeless onboard storage formats. Note: The capacity of the media is constantly increasing, so the figures here were representative in August 2009.

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