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Nonlinear Acquisition

Dec 1, 2005 12:00 PM, By Simon Wyndham

One shooter’s hands-on tale from the future of video capture.

Considering the number of years since editing systems became predominantly nonlinear, I find it fascinating that we are still using tape-based cameras and acquisition. There are, of course, very sound reasons why tape has been retained as an acquisition medium. For one thing, tape is generally extremely reliable, assuming the recording mechanism is kept in good maintenance. Tape also allows the original footage to be kept for very long periods of time without degradation. Most important, though, tape is cheap.

Tape, however, is still a linear format, and many camera manufacturers realized that nonlinear acquisition was the missing link in the digital production chain. Instead of spending hours on logging and transfer, editors could copy shots straight to the editing system's hard drive as files. A nonlinear recording format could also potentially eliminate the risk of frame dropouts as well as allow far greater reusability of the recording media.

Sony entered the nonlinear capture (NLC) market in 2004 with its optical disc XDCAM system. Based on blue laser technology, the XDCAM line includes the PDW-510 and PDW-530 cameras. Both cameras utilize the same head, but the 530 is capable of recording to the 4:2:2 IMX MPEG format, whereas the 510 records only DVCAM. Both cameras record to the same 23GB Professional Disc system.

Panasonic is concentrating on its solid-state P2 system, which records to small solid-state cards. The main camera in the P2 lineup is the SPX800 which, for all intents and purposes, is an SDX900 with P2 recording instead of tape. The lack of a tape-recording mechanism has meant that the purchase cost of the SPX800 is less than its sister camera, even after factoring the price of a few P2 cards.

Both XDCAM and P2 have their advantages and drawbacks, but they have kick-started a trend that will be hard to slow down. Other manufacturers have realized this and joined the fray with their own offerings. Ikegami has (re-)introduced its Editcam system, which records to FieldPak removable hard-disk media. Interestingly, this system records both DVCPRO 50 as well as the Avid DNxHD codec. Thomson has announced its own Grass Valley Infinity system, which records to Iomega Rev hard-disk media (branded Rev Pro by Thomson), as well as to solid-state cards using a variety of codecs, including JPEG 2000.

Despite the introduction of the other NLC systems, XDCAM and P2 currently hold the market share for this new and exciting workflow paradigm. My own experience of these cameras comes from the XDCAM system I purchased earlier this year.

I went with the Sony PDW-510P (PAL). The recording media was cheap, and the camera head seemed exceptional with its extreme sensitivity. I appreciated the progressive scan option and high adjustability via the camera's many setup and paint menus. The XDCAM system also gave me the ability not only to archive the original footage, but also store all my edit decision lists and supplementary graphics and footage files on the same disc upon project completion. It appeared to be a complete acquisition, editing, and archive solution.

Using the camera itself is not much different from using any other. The way that I like to look upon NLC systems is that they do everything your old camera does, but with the addition of features that you wished you could have had with the old one.

One advantage of using a NLC is the ability to delete no-good takes. There is a school of thought that says that one should keep all the takes just in case an element from one take can be combined with another if there is a problem. This remains perfectly true. There are, however, often times when you know that a take is completely useless and would normally just take up valuable space.

A case in point involves one of the first projects on which I used the XDCAM system. The independent digital feature, The Silencer, was partially shot with another camera. The gritty style of the movie and some of the dark night-time city locations, however, lent themselves well to giving the 510 a good workout. The Silencer contains a number of Hong Kong-style fight sequences. This style of screen fighting is extremely difficult to do well, and often uses up a quite inordinate number of takes.

Using XDCAM during this type of sequence proved exceptionally useful. Not only could the useless takes be deleted straight away, but the instant playback offered by the camera also meant that the stunt performers could easily be shown exactly how a take looked, allowing them to improve their movements for a subsequent retake.

Shooting these sequences took place many miles from base, so I also made extensive use of the PDZ-1 software. This enabled me to construct an instant edit of the action sequence after shooting to make sure that the sequence flowed as intended.

NLC acquisition has other benefits, too. The ability to add essence marks helps greatly during the recording of long events, such as sports. An essence mark is a digital marker in the recording that can be used for different purposes. One example would be for the camera operator to insert one at interesting points during the recording. If you are recording a football game, an essence mark can be inserted manually when someone scores. This can save the editor time in searching for the more interesting bits.

These functions are only the very tip of the iceberg when it comes to the capabilities of the new cameras. In terms of actual video production, however, it has meant that my videos can be turned around much more efficiently. My clips are more organized before editing has even started, and I can zip through footage much like one would look at photos on a digital still camera. For the cameraman and editor, it means that the production experience is much more streamlined. Transferring footage becomes fun rather than a chore.

I recently worked on a project based in the Welsh Mountains. The location was extremely remote, but the shooting schedule allowed me to use Sony's PDZ-1 software on a low-powered laptop and create a rough edit in my downtime. This meant that when I got back to base, all I had to do was tidy up the rough edit a bit, grade the picture, and mix the sound. All of my initial groundwork for the edit had been done on location.

In reality this might have only given me a small speed edge over traditional ingest and postproduction. The sheer convenience of the workflow, however, meant that I could just get on with the edit using minimal-powered hardware in a very remote location, very easily. Using a nonlinear capture workflow won't make things instantaneous, but it will make things much more streamlined.

For an NLC system to bring you total benefit requires that you embrace all the extra features that such equipment brings to the table. One will achieve nothing over a standard tape-based system if the footage recorded on a PDW-530 is transferred via an SDI connection. Also, the relatively expensive disc or solid-state media introduces a possible drawback to nonlinear capture. Unless you work for a company that uses one of these systems, or you are an independent, you might have a problem handing over your footage to a third party. As a result, tape may be the dominant acquisition medium for many users for some time.

The NLC revolution shows no sign of any letup. Panasonic is releasing its high-definition HVX200 P2 camera this month. Sony is close to releasing the first incarnation of HD XDCAM, a 1/2in. CCD camera that records to the same 23GB disc media as its standard-definition cousins.

Ultimately, whether or not a nonlinear camera will suit your company will depend entirely on your circumstances and workflow needs. For many outside news operations, there may not be a pressing need to upgrade. I can categorically say, however, that once you have used such a system you won't want to go back to tape ever again.

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Simon Wyndham is a freelance cameraman based in the U.K. To view video clips of XDCAM in action, visit www.simonwyndham.co.uk.

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