The Zombie Stack Exchanges That Just Won't Die
I have some extremely valuable film footage that currently only exists on multiple copies of a DVD+RW disc. The film was digitized in 2003 but I currently don't know the specifications of either the digitization process or output format on the DVD.
Currently, for reasons of storage and available expertise, I'm converting our digital video files to MPEG-4 File Format, Version 2 with AVC, High Profile (MP4_FF_2_AVC_HP or H.264) as it is widely used and according to LOC specs it is "designed to enable a high compression capability for a desired image quality". However, my goal is to create uncompressed video preservation files and figured this important footage merits the extra storage needed.
But what uncompressed preservation format to extract the DVD to, and how to do this? I see that JPEG2000 in an MXF container is used and recommended by LOC, but haven't found how they convert to this format. Daisy-chaining open source tools seems possible, but complicated and error-prone. There also seems to be disagreement on JPEG-2000 as a preservation format. Should I extract to uncompressed AVI? Is the DVD footage already compressed, and thus not worth extracting as uncompressed footage?
Matthew McKinley
Whenever I need to identify the content of a video file I use Media Info. It should be able to give you all of the information you need.
As for chaining together open source programs, that's often the best way to go. You can eliminate some of the potential for errors by writing a script or Makefile that will perform all of the steps for you. This makes it repeatable, should you need to do this for another dvd in the future, or in case you decide to revise the process later. I can also serve as a form of documentation of what you actually did, especially if you use version control.
I don't know what format is best for you at this point. If it's an ordinary dvd then I would just rip the MPEG2 stream to a file and save that. MPEG2 is a lossy encoding scheme, as are virtually all other video formats (including MotionJPEG). Reencoding to another lossy format is just going to reduce the overall quality of the data, even if you go to a more efficient MPEG4/H.264-based format.
If this is the only copy you have of this film that you can use for preservation purposes, you have to now consider it the original, and treat it as such. If this is an "authored" DVD, and not a data DVD, the video has already been encoded and compressed (using lossy compression) to a particular format: MPEG-2 with a colorspace of 4:2:0. In order to create an archival video file from this DVD, you should capture it at its native encoding and resolution. Using VLC or ffmpeg (if you are comfortable on the command line), capture the MPEG-PS or TS file without applying addition compression or transcoding. You will have the native file and the highest possible resolution in a self-contained MPEG file.
To answer your question "Is the DVD footage already compressed, and thus not worth extracting as uncompressed footage?" the answer is yes: this is heavily compressed content and you will not gain anything by upconverting to uncompressed or transcoding to JPEG2000 except for a bunch of bits and the need for additional storage space.
If your archive has a normalization policy for video such as what you describe above, you could consider transcoding to this format (taking care to preserve characteristics such as the aspect ratio and frame size). But I would advise keeping the MPEG file as your original master, in line with the archival practices of retaining originals.