![The Library of Congress has formed a growing network of preservation partners both in the United States and abroad to help save digital information that would otherwise be lost.](https://webarchive.library.unt.edu/eot2008/20081126202017im_/http://www.digitalpreservation.gov/images/partner_header.jpg)
Interview with Nan Rubin, project director of the Preserving Public Television project, Page 1
Following is an interview with Nan Rubin, project director of the Preserving Public Television project. The interview was completed in August 2005. More details on Thirteen's project can be found at www.ptvdigitalarchive.org.
When did producers such as Thirteen and WGBH begin producing programs in digital formats for distribution by PBS?
There are a few things to keep in mind when asking about digital formats of programs:
- A number of digital formats are used in program production, that is, the formats used for recording, acquiring and editing public television programs.
- Totally different digital formats are used for program distribution, which vary because of the different distribution channels used to get a program from PBS to each public television station.
- That's not all. There is yet another set of formats that are used solely for local on-air broadcasting, based on play-out servers, automation systems and other operational equipment.
Generally, distribution and broadcast formats are more compressed and of lower quality than production formats. One of our problems is to figure out how to maintain the highest quality video format while capturing the content of a program when it's "broadcast," since saving the program using the distribution or broadcast format isn't necessarily going to be the best for long-term preservation.
Digital videotape has been in use since the 1980s. The D1 and D2 videotape formats were developed to allow recording the video signal on tape in a digital form, allowing multigeneration recordings with minimal impairment. But they could only be used for recording, and the digital signals were all translated into an analog signal for distribution and broadcast.
Then, in the 1990s, advances in digital signal processing made it possible to build in "compression" that was useful for saving video using smaller files. One form of compression was standardized as JPEG (Joint Photographic Experts Group), which also came into common use for moving pictures as motion-JPEG, (M-JPEG). JPEG compression made the nonlinear editor and video server practical. This was followed by the development of the MPEG-1 (Motion Picture Experts Group) format for low-quality video, and later MPEG-2 for broadcast quality video and better.
Digital production, then, has been in place since the mid-1990s, but digital recording has been around a decade longer. All of us – Thirteen, WGBH and PBS -- have programs that were recorded on older digital formats like D2, and right now, we consider D2 to be a highly at-risk format.
Today, the broadcast chain from the production end is virtually all digital. Most of the broadcast end is all digital as well.
However, the distribution segment in between is not yet totally digital -- it still has a number of analog elements. If all goes according to plan, by the end of 2006, PBS will have completed the Next Generation Interconnection System, which will be a complete digital chain from end to end.