Putting the Time Base Back in Time Based Media Conservation

Benjamin Turkus and Kelly Haydon
The Electronic Media Review, Volume Four: 2015-2016


For the video formats that require the stabilizing force of a time-base corrector (TBC) to be digitized, the selection of TBC is second to only that of the videotape recorder. Despite the critical role played by these remarkable, increasingly obsolete machines (the earliest of analog-to-digital devices), their inner-workings remain a mystery to many of those responsible for reformatting analog video materials. Color, definition, stability, interlacement errors, preponderance of drop out—these things all rely, and, to a certain extent, vary, depending on the choice of TBC. During this presentation, members of the Bay Area Video Coalition’s (BAVC) Preservation team will stake a renewed claim for the significance of TBCs in media conservation, as under-discussed, yet essential, components of video and digitization systems.

Beginning with an overview of helical scan recording tech­nologies, Haydon and Turkus will deconstruct the time base, which, like all forms of video technology, is rooted in the rapid-fire transformation of light into electronic signal. Pinpointing the various distortions (tape damage, stretching, mechanical speed variation, oxide loss, etc) that can affect the sync pulses that play a critical role in the playback of recorded signal, Haydon and Turkus will walk the audience through why time base errors occur, and how these devices correct them. Presenting a series of case studies from the recent BAVC preservation projects, with a particular focus on formats from the heyday of video art (CV, EIAJ-1, ¾’’ U-Matic), the speakers will use side-by-side visual comparisons and analytical data provided by QCTools to demonstrate the at-times subtle, at-times signifi­cant differences between time base correctors.

With relevance for both in-house and outsourced video digitization projects, Haydon and Turkus will guide collections holders in taking a more active role in the selection of TBC, communicating with vendors both at the outset of a project (the Request for Proposal/Statement of Work process) and during playback testing. Haydon and Turkus will conclude with a critical look at the omission of peripheral machines, such as TBCs, from discussions of the magnetic media crisis. The obsolescence factors that affect TBCs, and the difficulties (and expense) of repairing and procuring functioning TBCs on the open market will only increase in magnitude in the coming years. Just as time-based media conservators should know the names of TBC manufacturers, they should also begin actively preparing for this inevitable decline.

Benjamin Turkus
Preservation Project Manager
Bay Area Video Coalition
San Francisco, CA

Kelly Haydon
Bay Area Video Coalition
San Francisco, CA