As Keely pointed out in the interview, decisions on video formats are more complicated than still images. Video formats for preservation purpose must be of lossless or uncompressed. Due to huge storage required by uncompressed files, lossless compression is usually more desirable. In addition to selecting a codec, several parameters are critical to encoding, such as frame rate, frame resolution, aspect ratio, interlace mode, pixel format (e.g., a variety of YUV formats), color space, and so on. All of those decision points apply when to produce presentation versions, with one more important consideration of bit rate, especially essential to deliver contents in an ecosystem of varying devices and network bandwidths.
In audio preservation there are more consensuses on preferable formats such as Broadcast Wave, whereas in the video sphere there is less agreement with codec or container format. The recent course of action by some facilities in Library of Congress to adopt MXF-wrapped JPEG2000 as the video preservation format might be a sign for the future. It is interesting to track how influential this LC’s decision would be on other libraries.
I think the greater turbulence in video world is due to the fact that the video technologies are still rapidly evolving. Not too long ago, people just started to accept HD. Now the industry is pushing 2k or 4k. By contrast, technologies in still image and audio are relatively matured and stabilized.
Besides file formats and technology issues, the challenges in video digitization librarians have to deal with are basically the same as other types of digitization. As mentioned in Liu’s paper, librarians have to determine the prioritization of what to be digitized, standards to be used, copyright policies, and so on. I believe the prioritization is particularly challenging in video digitization because there are already enormous amount of born-video and they are expecting to grow exponentially. Moreover the cost of video preservation is far higher.
Finally I would like to describe a little bit about container. Many people have already used container without knowing it. For example, the popular AVI or MOV are actually container format. Containers are able to carry contents encoded by different codec. So an MOV file may contain AVC contents encoded by .H264 codec or just an RGB uncompressed stream. The question is why we want to have this additional layer. The major motivation is for cross-platform interexchange. Theoretically a container can wrap any data conforming to its specification. In addition to video frames or audio samples, a container can carry “payloads” for packaging, transporting and presenting purposes. The aforementioned MXF format adopted by LC is an SMPTE standard widely used in professional video and audio media. The wiki page at http://en.wikipedia.org/wiki/Comparison_of_container_formats well compared an array of container formats.