Tapeless camcorders
Jan 1, 2009 12:00 PM, By David Austerberry
The Thomson Grass Valley Infinity camcorder can record video files to a removable hard drive or solid-state Flash memory.
By the 1980s, video recording had successfully developed to the point where a VTR could be squeezed into a camera body, creating the camcorder. The requirements for a camcorder must have been challenging for early developers. The deck had to operate with a low power drain, be small, not be upset by motion and vibration, and work in extreme climatic conditions. The Betacam family of 1/2in decks and the 1/4in DV are a good example of just what can be achieved. These formats have even been adapted to support HD, with HDCAM, DVPRO HD and HDV. However, successful tape has proved to be, tape is still linear, and it stores video data. Broadcasters now want nonlinear file-based recording to fit better with their IT-based systems and to allow more flexible workflows.
Camcorders are a great example of the compromises that are inevitably part of engineering design. They must deliver superb pictures, but have a low power drain on the batteries and be light enough to carry around all day. Power is limited to about 40W by current battery technology, and weight to around 5kg (excluding the lens and battery).
Current videotape technology has reached a write speed of 440Mb/s for HDCAM-SR (880Mb/s at double speed), which sets a quality benchmark for acquisition. Camera operators have come to expect a record duration of around two hours from a single cassette, again setting an expectation for different media.
Currently available tapeless media, that is affordable and practical, is limited to around one hour (for HD) and a maximum data write speed of about 100Mb/s. That means compression is essential. Today, if you want 1080p50 4:4:4 recording, then a separate storage device must be used. No doubt in a few years it will be feasible to record a 3Gb/s stream to onboard storage.
It has been a long time waiting for other storage media to offer the features provided by tape. Cost and record duration were two obstacles. The broadcast environment, especially ENG, can be hazardous to technology. Reliability is essential.
Consumer technologies have been adapted to meet broadcast needs. One example is Blu-ray. A second is solid-state memory. A third, the hard drive, is forever decreasing in cost and increasing in capacity. All these technologies can now offer competition to conventional videotape, but with the major advantage of nonlinear access.
Making a choice
Choosing a camcorder used to be dictated by the type of tape: 1/2in or 1/4in, digital Betacam or DVCPRO. Now deciding on a camcorder starts with the media. Do you want an instant archive, or do you want to put off that decision?
Videotape is cheap enough to use once and keep on a shelf. When shooting to tape, that same tape can also be used to archive the production. As magnetic tape has a typical life of 25 years, any need to preserve the content long term can be put off well into the future.
Shown here is the Panasonic AJ-HPX3000 P2 camcorder at the 2008 Beijing Olympics games.
Two tapeless formats are a similar cost to videotape: the optical Professional Disc and REV PRO. These can be employed in a similar way to tape, used once and stored away as a permanent archive of the production.
Currently, hard drives and solid-state drives (SSDs) are too expensive to use once and put away on the shelf. Instead the files must be copied to disk storage arrays for post production. The SSD can then be wiped and used for the next shoot. After post production, the show can be archived to a long-lasting and low-cost medium, such as data tape, to free space on the storage array.
Portable hard disk drives (HDDs) similarly should only be used for temporary storage. There are many stories of shows stored on portable drives that have been put away on a shelf. Five years later, the drive will not spin up and read back the data; drives like to spin continuously.
Your choice of acquisition medium is dictated by your workflow and by the program format. Sitcoms are long-lasting formats that can be sold way into the future. Other formats are transient and not worth the cost of archiving. News clips are short and are better stored in a managed archive, so the original camera media can be wiped and reused.
Once you have selected the media that best fits your budget and workflow, then it's down to the features and facilities. One big decision is whether to use a 2/3in or 1/2in lens. You may have a stock of lenses to reuse, or the program genre may dictate 2/3in. For programs shot on a smaller budget, 1/2in could be the ideal choice. It may even be appropriate to use a smaller sensor, perhaps a 1/3in camera with a fixed zoom.
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