IASA-TC 06 video guideline: video's technical complexity, challenging preservation issues

This is the second of a series of five blogs on IASA-TC 06 by the guideline's coordinating editor Carl Fleischhauer.

The preceding blog in this series reported on the slow progress of the initial drafting of IASA's Guidelines for the Preservation of Video Recordings, IASA-TC 06.  This pace motivated the IASA Technical Committee (TC) to revise their plan for a single comprehensive edition to a two-part phased project.  What makes the topic of video preservation so challenging?  Short answer: big topic, few available authors.  Video is a deceptive singular noun: any comprehensive preservation guideline will be about a far-flung family of technologies.  And although there are many experts, only a handful are able to devote voluntary time to drafting explanatory texts.

Video's technological complexity has been there from the early analog days, as television took shape as a medium of mass communication.  For engineers, there were a number of key problems to solve.  One was the need to standardize methods to synchronize the lines, fields, and frames that comprise the video picture, to ensure a stable presentation on the screen.  Even in the monochrome era, standardization on this front came slowly and saw considerable international variation, and this intensified as color imagery came into play.  

A second key problem concerned bandwidth (or the lack of it).  Think of the pictures on the screen, accompanied by sound, as a "two-kilogram" requirement.  Think of the systems that carry the picture and sound data to the screen as having a "one-kilogram" capacity.   Engineers worked out a number of tricks to move two kilos of picture and sound to the screen and loudspeakers in a one-kilo package.  (Or, more to the point when preserving old recordings, to record two kilos on a one-kilo-capacity videotape.)  From at least the 1950s forward, analog video systems employ bandwidth-savers like picture interlacing, composite "color-under" recording, and more.  Meanwhile today, digital video is rich in options for the "lossy" compression of data to support broadcasting and, today, Internet-based dissemination.

Finally, in order to serve the needs of broadcasting, solving the two key problems described above moved in parallel with the standardization of what is called ancillary data, e.g., time code (including drop-frame time code), captions and subtitles and other data to assist consumers, and more.  All aspects of video technology took shape in the context of the existing national and regional electrical grids.  For example, the (nominal) 30 fps and 25 fps frame rates employed by the three main television standards NTSC, PAL, and SECAM, were influenced by the presence of 60 cycle-per-second power in the U.S. and 50 cps in Europe, echoed in Japan's somewhat schizoid maintenance of both rates.

Digital formatting has contributed (albeit fitfully) to the reduction of some forms of complexity, e.g., interlacing.  At the same time, recent advances in digital formatting include notable expansions: higher spatial resolution (HD and UHD, Ultra High Definition), greater tonal range and contrast (HDR, High Dynamic Range), a variety of additional frame rates, "immersive" surround sound, adding more kilos to the content that engender their own digital tricks to reduce bandwidth.  To say nothing of Virtual Reality (VR) formats, now seeing a ground swell of new production.  Many of these digital developments start in professional circles and trickle down to independent productions, documentaries, and YouTube clips, although it may be the case that VR moves from the bottom up.  

As noted in the first blog in this series, the first edition of IASA-TC 06 will focus on the preservation of video recordings on conventional carriers.  For the most part, this means the digitization of analogue videotapes, but it also encompasses the transfer of content from some types of digital videotapes.  The sections devoted to conventional carriers include sections on:

• Quadruplex 2-inch Videotapes
• EIAJ and Sony CV ½-inch Open Reel Videotapes
• 1-inch Helical-Scan Open Reel Videotapes (types A, B, C)
• U-matic ¾-inch Videocassettes
• ½-inch Analogue Consumer and Semi-Professional Videocassettes
• Betacam ½-inch Professional Videocassette Family

We believe that these sections will have enduring value and the TC offers its grateful thanks to authors and advisors George Blood, John Bostwick, Kevin Bradley, Charles Churchman, Ross Garrett, Lars Gaustad, Dinah Handel, Andrew Martin, Andrew Pearson, James Snyder, and Tom Sprague.  

In contrast, some other topics and issues are volatile and proved especially challenging as this edition was drafted.  They are sure to see adjustment and refinement as time passes:

• The identification of digital target formats
• The problem of retaining the full video "payload" when digitising
• Facility design as "the industry" moves from serial interfaces to bitstream movement via IP networks

These three topics are the subjects of the three blogs that follow.

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