DIGITAL PERSPECTIVES

Archivists Warn: Don't Depend on DAT

by
Frank Beacham

In recent years film and video makers have embraced the DAT audio format as a convenient and economical way to record and store high-quality location audio. Now some of the world’s leading audio preservationists are warning that tape-based digital recording media – especially DAT – is not reliable for long-term archiving of sound.

During a recent AES panel discussion on digital audio, the archivists urged recording equipment manufacturers to quickly create reliable long-term storage media for analog and digital audio recordings. There was a consensus that, at least for now, analog tape is the only proven, reliable way to preserve sound recordings for the future.

Ironically, one of the most passionate pleas came from Marc Kirkeby, senior director of the American music archives for Sony, a company that is not only a leading manufacturer of digital recording equipment and media, but the owner of more than 600.00 recordings dating back to the turn of the century.

"The potential for disaster out there cannot be overemphasized," said Kirkeby, who noted that most valuable recordings are retrievable today only through blind luck. " We have tapes from 1949 that sound wonderful," he said. "We have tapes from 1989 that are shot to hell. And it’s all just chance."

Kirkeby said that now, 15 years into the digital recording era, "it is painfully apparent that there has not been a digital medium introduced that really serves an archival purpose. If you have to go to bed at night wondering if your tapes are going to be there in the morning, that’s not an archival medium."

Sony Music, like most other record companies, has no systematic program to preserve aging master recordings, Kirkeby said. 
"We archive to analog on as-needed basis and we archive digital-to-digital," he said.

DAT cassettes, said Kirkeby, are especially unpredictable in their reliability. He said he’d bet his pay that analog originals will outlive DATs. "There’s always that little moment when you put the thing in the machine," he said. "Is it going to play or not?
If you knew that outside of 10 years certain chemistry aspects would start to change, then you could allow for that. But, if youcan’t predict it, how do you plan? That’s my problem with DAT."

Though there were no location sound recordists for film or television on the panel, all the participants use the same equipment and techniques that are employed on visual productions. Virtually all of the panelists cited problems with the DAT format as an archival medium.

DAT was criticized by John Barnes, a European specialist in operatic archival recording who has used the format at the Glynbebourne Festival Opera in England. "We’ve had very bad experience with DAT tapes and, in particular, DAT housings," he said, estimating that he finds an average of one malfuncti- oning DAT tape out of every 20 he uses.

"I’m not at all happy about the use of DAT tape as a long-term storage medium and we’ve got to try to find an alternative," he said. "(There are) far too many failed masters and failed copies using so-called high quality professional grade DAT tapes."

DAT was also maligned by Gerry Gibson, a specialist in electronic media preservation at the Library of Congress andchairman of the AES Audio Preservation Standards Group. 
"We believe that long-term preservation of audio will be digital," said Gibson. "For now, however, our experience is the current digital media and systems are not appropriate for long-term storage or preservation.

For preservation, said Gibson, the Library of Congress - the largest information collector in the world – depends on half- track, quarter inch analog audio tape for backing up its over three million sound recordings. "Further, we are very leery of any compression schemes for the long-term storage of preservation masters because of fear that compression means loss of information regardless of how good the algorithm is", he said. "I have reservations, as an archivist and a historian, that I can really rely upon that machine to make the decision as to what’s not useful data."

Veteran recording engineer Roger Nichols, who said he’s a regular user of DAT himself, warned recordists to treat the digital cassette format as a temporary medium. "Where in archival you are worried about longevity, the DAT tape isn’t quite going to make it," he said. "As for a medium for temporarily storing your data, it’s (acceptable for) a year or so, but you will eventually transfer (the data) to something else."

Alignment of DAT machines is a major reason for the problems, Nichols said. "If you look at a DAT alignment tape on a machine, there’s a DAT standard of plus or minus 10 percent," he said.
"You (use) one machine that’s 10 percent one way within the DAT standard and you want to play back on another machine that ten percent the other way, but it’s not going to (work). I run into problems all the time with DAT compatibility."

As for alternative digital storage media for preservation, several panelists said they are currently investigating alternative possibilities. The recordable CD format – CD-R – is most promising so far, they said.

"We tried CD-R for the first time this year and have been very happy with it," said Barnes. "The only problem at the moment is recording length. Seventy-four minutes is too short. We need something in excess of 120 minutes."

Audio recordists, said Sony’s Kirkeby, need desperately to get beyond their dependence on "the medium of the moment" and find a digital audio backup system that offers long-term stability".