By Russell Whittaker
Video Transfer hosted the December 10th meeting on new digital tape formats. Karl Renwanz gave tours of his full-featured duplication facility, with its encyclopaedic collection of tape machines. It was an appropriate location to discuss new tape formats, with almost every format of the last twenty years in the room next door.
There were four presenters of new and economical digital tape formats. Behind these exciting new products were three distinct strategies on how to bring the benefits of digital recording to a wider market. And throughout it all was a reminder of all of the other machines that have been brought out and the compatibility problems that result.
Ralph Biesemeyer of Panasonic started the presentations off with an introduction to the DV Consortium. 56 companies knocked heads to produce a consumer format standard. The result was a standard with 4:1:1 sampling and a 5:1 compression housed in an incredibly small package. The format anticipates improved performance and allows for 4:2:2 sampling at 50 Mbs.
DVC Pro, as the name suggests, is essentially a professional version of the DV format. A control track, cue track and overall wider tracks were grafted onto consumer DV. It uses a 1/4" metal particle tape. Compression is intra-frame to allow for editing.
The family of products includes a camcorder (AJ-D700), a recorder (AJ-D750) and a laptop edit controller (HAD-650). At IBC, Panasonic announced that they will take advantage of the higher data rates supported by DV and introduce a 4:2:2 version of DVC Pro.
Panasonic now has five tape formats which are being sold (S-VHS, D3, D5, HD DV and DVC Pro) Each addresses specific markets. There was no talk of compatibility of these formats (the signals they produce is another matter). Rather they have been designed to meet specific needs with no one machine attempting to be all things to all users.
Jerry Cohen of JVC discussed Digital S at length and distinguished it from the DV formats. In particular, he emphasized its 4:2:2 sampling and pre-read functions. It has, he feels, the broadest range of applications of the available digital formats. With no other professional digital formats, JVC has developed a machine which will meet a wide number of needs.
Digital S uses a 1/2" cassette and is compatible in its physical construction to S-VHS. The specs are 3.3:1 compresssion of a 4:2:2 signal. The data rates supported are 50Mbs. Additional control tracks and two auxiliary data lines are stored. Based on the amount of chroma bandwidth, the result is a picture better than any analog of 1/4" digital format. The areas where 4:2:2 processing is important include computer graphics, chromakeying, digital effects and compositing.
Head-assembly of the Digital S machine was covered in detail. There are stationary upper and lower drums to maintain tape linearity and in the future, heads to allow the playback of S-VHS tapes (a rare example of corss-format compatibility). An extra set of heads on the BR-D85 support pre-read editing. They are placed such that they can record to the exact spot on the tape with a two-frame delay. This provides a two-frame window for switcher manipulation.
Pre-read produced strong feelings. Some of those in attendance came to its defense. For others, it is a risky and a bit unknown. Its popularity is due in large part to the cost advantage of saving a D2 machine. With the low price of the new digital formats, that is not as big a savings as it once was.
Sony Corporation made two presentations. Vinnie Froio covered DVCam and Nick DiLello gave an introduction to Betacam SX. Because it was getting late, both of their presentations were brief. DVCam and Betacam XS are two integrated families of products that link acquisition and editing.
DVCam is a 4:1:1 format that uses 5:1 compression to record onto a DV tape. These tapes also have 16K of memory to store Cliplink logging information. Cliplink allows potential edit points to be identified when they are shot. A rough storyboard is produced, and program material can be transferred to disk selectively. This greatly speeds up transfer and saves on disk space.
The DVCam family consists of cameras, camcorders, players, recorders and edit stations. The VTR alone comes in 5 versions, from a dockable deck to a high-speed editor. There are both digital and analog I/O so most peices could drop into an existing system. However, to take advantage of DVCam is to use all of the pieces of the system. In particular, the edit stations which use Cliplink and come with integrated effects.
The hybrid DNW-A100 is the flagship of Betacam SX. It also comes with a built-in hard disk to take integration even further. 4:2:2 Studio Profile is designed to meet the quality requirements of editing and special effects while providing relief in storage and transmission. The compression is 10:1 and the resulting data rates are 18Mbs. But because the images are MPEG compressed, the image quality is close to that of 2:1 Digital Betacam. Betacam SX tapes are the same size as regular Betacam tapes, and the machine can play back regular Betacam and Betacam SP tapes.
There are four acquisition cameras, a laptop editor, a live editor as well as uplink and downlink equipment to round out the family. They of course are designed to work together, but Betacam SX will fit into an existing system. This should get the attention of anyone with a Betacam machine in their plant.
The final presentation could have been titled 'Back to Chemistry Class'. Ron Weiss of Arkival Technology discussed long-term tape storage using Barium Ferrite (BaFe) tape. The U.S. Government funded development of a tape with superior archiving capabilities, so in a sense, we have already paid for this already.
Barium Ferrite has a number of properties that make it ideal for tape: It is chemically stable, resistant to dirt and humidity, and it has very good frictional properties. Foremost of these is the fact that it is chemically stable. This insures the long shelf life that the government was looking for.
It works better at high frequencies. Audio and cue data are a problem as are earlier formats such as U-Matic. The new digital tape formats with their relatively high frequencies are good candidates for this tape.
The formal presentations were followed by a touchy-feely session with the equipment. Each of the machines came with its own footage, so direct comparisons were not possible. Buyers must evaluate their specific needs and the direction of their company to make sense of these new digital options.
All of the machines produced great pictures...
Russ Whittaker works for ECHOlab, the switcher manufacturer in Burlington MA. He can be reached at (617) 273-1512.