Movie Corruption Issue
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heckman@bgnet.bgsu.edu |
Re: Movie Corruption Issue & Codecs
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http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal Steve- "the prospect of retroactively re-encoding 5 years worth of compiled imaging data solely to..." This is supposed to be what computers are good for. Maybe you need a good programmer. Carol |
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In reply to this post by Mathieu Marchand-2
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The message really seems extremely clear. Do not use Quicktime
under any circumstances. If you have old movies in QT format
convert them all on an old system (preferably isolated from the
Net) to something that has open source support. (There is
probably a freeware Linux product that will do this as a batch
process). But these formats are NOT designed for scientific
data - it may be fine to use a QT movie as a one-off to show
at a conference (though from the number of problems I've
seen on this front I'm not convinced!) but scientific data should
be saved as as uncompressed image series in formats that
will always be openable (even if not immediately playable as a
movie). It's not realistic to expect entertainment software to
offer the data stability that science needs.
Guy
Optical Imaging Techniques in Cell Biology
by Guy Cox CRC Press / Taylor & Francis http://www.guycox.com/optical.htm ______________________________________________ Associate Professor Guy Cox, MA, DPhil(Oxon) Electron Microscope Unit, Madsen Building F09, University of Sydney, NSW 2006 ______________________________________________ Phone +61 2 9351 3176 Fax +61 2 9351 7682 Mobile 0413 281 861 ______________________________________________ http://www.guycox.net From: Confocal Microscopy List on behalf of Mathieu Marchand Sent: Sat 08/01/26 5:16 AM To: [hidden email] Subject: Re: Movie Corruption Issue Search the CONFOCAL archive at |
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http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal On Mon, 28 Jan 2008, Guy Cox wrote: > Search the CONFOCAL archive at > http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal > > The message really seems extremely clear. Do not use Quicktime > under any circumstances. If you have old movies in QT format > convert them all on an old system (preferably isolated from the > Net) to something that has open source support. (There is > probably a freeware Linux product that will do this as a batch > process). Yes, it's the encoding command like variant of the mplayer I wrote about. When used for translating between codecs, the command is "mencoder." > But these formats are NOT designed for scientific > data - it may be fine to use a QT movie as a one-off to show > at a conference (though from the number of problems I've > seen on this front I'm not convinced!) but scientific data should > be saved as as uncompressed image series in formats that > will always be openable (even if not immediately playable as a > movie). It's not realistic to expect entertainment software to > offer the data stability that science needs. > Mencoder can also output as a series of stills. I'm not sure I would agree that video *captured* as video needs to be stored as stills. Storing as stills does not obviate file format obsolescence. First, of course, most (though by no means all) video, even high end, incorporates a bit of lossy compression during capture. Storing these in uncompressed image formats is closing the barn door after the horse is gone. Second, there are well known, open source, lossless compression algorithms that are pretty stable over time and supported by multiple still formats, and uncompressed still images don't have an advantage over them. There is, fundamentally, *no* advantage, for instance, to saving a file in uncompressed TIFF over LZW compressed TIFF. If LZW compressed TIFF format becomes obsolete, then the TIFF format will be obsolete and you'll have to resave the images in whatever comes next anyway. Similarly, the codec specification for DV is part of the DV format specification, and if that codec becomes obsolete, then DV is obsolete. Third, saving images as stills in no way guarantees that it will always be available. When was the last time you worked with Targa/Truevision graphics adapter (.tga) files? The bottom line is that saving images as stills may delay the issue of format obsolescence, but will not remove it. TIFF, for instance, will become obsolete in the next few years -- it is a proprietary format owned by Adobe, and has not undergone significant development. Eventually, it will slip into obscurity the same way that GIF is slowly doing. The bottom line is that there is *no* image format, still or video that will save you from format obsolescence. Rather than try to save images in file formats that will not need revision, it is probably more prudent simply to have an SOP for periodically or continuously monitoriing the status of your files and a plan for migrating them when obsolescence inevitably starts. One good resource, by the way, for finding out what software deals with what format is the PRONOM database in the UK. See: http://www.nationalarchives.gov.uk/pronom/# Another good site is the wotsit database: http://www.wotsit.org/ One discussion of developing such an SOP can be found at: http://www.dlib.org/dlib/november04/stanescu/11stanescu.html See also: http://www.clir.org/pubs/reports/pub93/pub93.pdf billo |
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Well, I have several programs that will convert tga files. Since all
the imaging software folks have already written their tga readers
(as, indeed, have I) they are unlikely ever to disappear, however
rarely they are used. LZW compressed TIFF is, I agree, unlikely
to disappear but since these files can often be larger than
uncompressed ones there is little reason to use them. Even
if a format is lost off the face of the earth, uncompressed image
data can usually be retrieved while compressed data is more
tricky. There are readers out there even for old, strange,
confocal and image analysis files (some with non-square pixels).
Why? Because they are scientific formats and there is a real
need to preserve scientific data.
Entertainment formats have a short life - technology advances
and nobody is interested in the clunky technology of 5 or 10
years ago. Science and entertainment have very different
requirements.
Guy
Optical Imaging Techniques in Cell Biology
by Guy Cox CRC Press / Taylor & Francis http://www.guycox.com/optical.htm ______________________________________________ Associate Professor Guy Cox, MA, DPhil(Oxon) Electron Microscope Unit, Madsen Building F09, University of Sydney, NSW 2006 ______________________________________________ Phone +61 2 9351 3176 Fax +61 2 9351 7682 Mobile 0413 281 861 ______________________________________________ http://www.guycox.net From: Confocal Microscopy List on behalf of Bill Oliver Sent: Tue 08/01/29 7:48 AM To: [hidden email] Subject: Re: Movie Corruption Issue Search the CONFOCAL archive at |
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