Published on June 26, 2007
Placing Movies in the PDS Archive: Placing Movies in the PDS Archive Engineering Node Pasadena, California Nov 30, 2006 http://pds.nasa.gov Background : Background At the November MC telecon, the following action item was assigned to the EN. 'Simpson suggested that EN be directed to present a summary of the issues that might be involved in drafting a MOVIE SCR at the Washington meeting'. Mars Pathfinder mission had expressed interest in archiving image sequences of the Rover acquired by the IMP camera as animated GIFs (not followed through on) SBN is considering how image sequences from Deep Impact should be archived. Propose placing them in the DOCUMENT directory as MPG files Huygens 'movies' were included in the archive under the EXTRAS directory Problem : Problem Current PDS standards do not adequately address this need The only current way to archive a sequence of images is by storing multiple IMAGE objects in the same file. Impractical from a storage perspective for anything larger than MPF Rover 'movies' Impractical from a display perspective, since it is unsupported by any software Only advantage is retention of full resolution images that comprise movie, but these are redundant with EDR products anyway Popular movie formats such as MPG and QuickTime cannot be formally archived using current PDS standards Cannot be labeled as a product since there is no MOVIE object Cannot be placed in the DOCUMENT directory since neither MPG nor QuickTime files are approved as acceptable formats for documents (as are JPEG and GIF) Issues : Issues What kind of a product is a movie? Some potential cases: Raw data product No existing examples (with possible exception of old lunar data from manned program?), but conceivable if a video camera were mounted directly on a spacecraft Derived science product Assumes data and/or images from which movie was created are already archived as more primitive products Do the Huygens movies fall in this category? Could include visualizations of science data collected by non-imaging instruments Another example might include gas giant cloud rotation movies Browse product Created by stringing together a sequence of already archived images Adds no science value other than convenience (?) Example might be MPF rover movie sequences Issues : Issues How to archive these products? Raw and derived science products Should be archived in a DATA subdirectory Should be archived with an as yet to-be-defined MOVIE (or VIDEO) object in a PDS label Should be archived in one of a strictly limited number of carefully researched formats Should be archived alongside display software and/or decoding algorithms Would require submission and approval of an SCR involving significant work (along the lines of JPEG2000 or greater) Browse products Should be archived in the EXTRAS subdirectory Would require no PDS label, and therefore no specific object No particular restrictions on format would be necessary, although a list of recommended, popularly supported formats could be provided in the PDS Standards Reference as guidance to data preparers Requires no changes to existing PDS standards Issues : Issues What about using the DOCUMENT directory? The DOCUMENT directory is not traditionally a place to store science products. Rather, the Standards Reference describes it as a place to store '[s]upplementary or ancillary reference materials…included with archive products to improve their short- and long-term utility.' Even if a specific movie format were added to the list of approved document formats, the inclusion of a movie in the DOCUMENT directory would still violate the requirement for all documents to be included in a 'flat, human-readable ASCII text version'. (It should be noted that simply because GIF and JPG are listed as approved formats does NOT mean that documents may be provided solely in those formats.) A movie stored in the DOCUMENT directory, without all the work done to archive it as a full data product with its own data object and documented format, would not be supported for posterity by the PDS in any meaningful way. Additional Considerations : Additional Considerations In selecting acceptable formats for archiving movies, the following questions (among others) need to be addressed: Is the format lossless (particularly important for raw data)? Does the format need to be capable of storing sound? What resolution do we need to be able to support? Full HDTV (1920x1080)? If less than this, by how much? What kind of display support do we want for the format? Popular software programs like Apple’s QuickTime or Microsoft’s Windows Media Player? Ability to play on any standard DVD player? Given the lack of control we’ll likely have over the format, which external standards organization should we require compliance with? ISO/IEC? Other? Next Steps : Next Steps Option 1 - Based on MC input and discussion of the issues EN will draft an SCR for adding MOVIE as a PDS Object in the archive. - or - Option 2 – Put the movie files in the EXTRAS directory.