Monday, April 10, 2017

Encoding and Wrapper Decisions and Implementation for Video Preservation Master Files

Encoding and Wrapper Decisions and Implementation for Video Preservation  Master Files. Mike Casey. Indiana University. March 27, 2017.
     "There is no consensus in the media preservation community on best practice for encoding and wrapping video preservation master files." Institutions preserving video files long term generally choose from three options:
  • 10-bit, uncompressed, v210 codec, usually with a QuickTime wrapper
  • JPEG 2000, mathematically lossless profile, usually with an MXF wrapper
  • FFV1, a mathematically lossless format, with an AVI or Matroska wrapper
The few institutions digitizing and preserving video for the  long-term are roughly evenly divided between the three options above. This report examines in detail a set of choices and an implementation that has worked well for their institution. Originally they chose the first option, but with recent advances of FFV1, they reopened this decision and initiated a research and review process:
  • Exit strategy research and testing
  • Capture research (use FFmpeg within their system to generate FFV1 files).
  • Comparison of issues
  • Consultation with an outside expert
Results:  Research into exit strategies, they were able to move FFV1 files to a lossless codec with no loss of data. They decided to capture using FFmpeg, which requires developing a simple capture tool, and developed specifications for a minimal capture interface with FFmpeg for encoding and wrapping the video data.

Technical:  identified a number of key advantages to FFV1, including:
  • roughly 65% less data than a comparable file using the v210 codec
  • open source, non-proprietary, and hardware independent
  • largely designed for the requirements of digital preservation
  • employs CRCs for each frame allowing any corruption to be associated with a
  • much smaller digital area than the entire file
FFV1 appears to be "trending upwards among developers and cultural heritage organizations engaged in preservation work". They also chose the Matroska wrapper, which is an audiovisual container or wrapper format in use since 2002, and which is a more flexible wrapper option.

As more and more archives undertake video digitization" they will not accept older and limited formats" (AVI or MOV), but they will be looking for standards-based, open source options developed specifically for archival preservation. "Both FFV1 and Matroska are open source and are more aligned with preservation needs than some of the other choices and we believe they will see rapidly increasing adoption and further development."

Implementation: They developed a quality control program to validate that the output meets their specification for long-term preservation and checks the FFV1/Matroska preservation master files. These files are viewed using the VLC media player, a free open source cross-platform multimedia player that supports FFV1 and Matroska

Currently, they have created over 38,000 video files using FFV1 and Matroska. "We have chosen two file formats that are open source, developed in part with reservation in mind, and on the road to standardization with tools in active development. We have aligned ourselves with the large and active FFmpeg community rather than a private company. While the future is ultimately unknowable, we believe that this positions us well for long-term preservation of video-based content."

No comments: