Workshop 4 audiovisual digital preservation strategy
1. Digital Preservation Strategy
Choices when moving
analogue to digital
Choices in the digital
world
Supporting choices with
good cost estimates
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2. Roadmap
Where am I, where do I go next
Audio: only one answer: uncompressed to .wav
file; some options
16-bit bit depth, or could go for “24”
CD sampling rate= 44.1 kHz; or 48 kHz or 96 kHz
BWF = Broadcast Wave Format version of .wav
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3. Video Roadmap
The basic problem: uncompressed video is 200
megabits per second = 100 gigabytes per hour
VHS quality is roughly 1 megabit/sec (AVC =
H.264 = MPEG-4)
DVD quality is roughly 5 megabits/sec (MPEG-
2)
So: hard to justify saving poor-quality video as
uncompressed video at 200 Mb/s
Compromise: “temporary archiving” in a
compressed format “for a few years”
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4. Video Roadmap
http://wiki.prestospace.org/pmwiki.php?n=Main.Roadmap
Clear statement for archived standard definition video
Input: Low, Medium and High Quality originals
Output: Access copy or Preservation copy
Access: DVD disc or MPEG-4 file
Preservation Roadmap:
Low: VHS, compressed digital DV file, 25 Mb/s
Middle: U-Matic, DV DV file
High: BetaSP, Digibeta, other pro formats uncompressed or
lossless compressed (JPEG2000)
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5. Video Roadmap
Much less clear for high definition video
Many production formats
Various kinds of “HD”
But:
Interlaced video should be saved as interlaced
Saving the 'native format' is ALWAYS good
Saving uncompressed remains a problem
BBC is promoting VC-2 codec (simpler than J2K)
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6. Too Many Video Formats !
The following are supported by one file converter (Total
Movie Converter):
Audio Video Interleaved (.AVI)
Windows Media Video (.WMV)
DivX Video (.DIVX)
XviD Video (.XVID)
DVD Video (.VOB)
Digital Video (.DV, .DIF)
Apple QuickTime Video (.MOV)
MPEG Video (.MPG, .MPEG, .MPE, .M1V, M2V, .MPV)
MPEG4 Video (.MPEG4, .M4V, .MP4)
Advanced Streaming Format (.ASF)
AVS Video (.AVS)
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7. More !
Intel Indeo Video (.IVF)
Matroska Video Stream (.MKV)
Mobile Phone Video (.3GP, .3G2)
HD Video (.H261, .H264)
JVC Digital Video (.MOD)
WinAmp3 Video (.NSV)
MythTV Video (.NUV, .NUT)
Flash video (.FLI, .FLC, .FLX, .FLV, .FFM,
.SWF)
Sony high definition video (.MTS and .M2TS)
RealMedia Variable Bitrate (RMVB)
Telesync (TS) Vietnam Film Institute Workshops
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8. Recommended for Video
Professional: MXF; does everything
Alternatives: MOV (Quicktime), AVI
But: AVI does not support timecode
And then: how do you store your files:
Hard drives
Data tape (LTO and a few others)
Optical media: CD, DVD
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9. File Formats for Film
DPX uncompressed, very flexible
DCI DCDM = Digital Cinema Distribution Master:
2048x1080 (or 4096x2160) only
DCP = Digital Cinema Packaging = lossy compressed
JPEG200; (not for master)
JPEG2000 (lossless); 2:1 data reduction
Various lossy compression formats (avoid!)
And … various wrappers: MXF, AVI ...
MXF (same as used in broadcasting – except there are
many versions of MXF)
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10. Migration of File Formats
(1 ) S TA R T H E R E
Is th e fo r m a t a
( 2 ) p r o b le m ?
Y E S
A r c h iv e fo r a
fe w y e a r s N O
(3 ) (4 )
(5 c ) W h a t c o s t/q u a lity /r is k
o p tio n c a n y o u a ffo r d
C o m p re s s
lo s s y
(5 b ) (5 a )
C o m p re s s U n c o m p re s s
lo s s le s s
E N D H E R E
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11. Preservation Strategy
Keep what you have as long as it works
Migrate to a new format when the old format
has a problem (usually, obsolete)
Examples: Real Audio, MPEG-1 Video
OR – maybe you can emulate the software
needed to use the file, even after standard
software no longer works
University of Liverpool: Multivalent Browser
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12. Strategy with Emulation
STAR T H ER E
Is th e fo r m a t a t
r is k ?
YES
A r c h iv e fo r a
fe w y e a rs N O
W h a t c o s t/
q u a lity / r is k c a n
y o u a ffo rd ?
C o m p re s s
lo s s y
C o m p re s s
U n c o m p re s s
lo s s le s s
M u ltiv a le n t EN D H ER E
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13. Storage Options
PrestoPRIME has lots of white papers
And tools for 'what-if' analysis of storage systems:
− How many copies do I need?
− Should I buy more discs, or use data tape backup?
− How often should I check the files?
Will give more detail on storage tomorrow
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15. Demonstration: Tools for
Understanding Storage
PrestoPRIME Online Tools
http://prestoprime.it-innovation.soton.ac.uk/
http://prestoprime.it-innovation.soton.ac.uk/
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16. End of Day One !
Thank you all
Tomorrow:
Storage and storage systems
Software for a file-based archive
Access
− All the problems
− All the opportunities
General Summary and Discussion
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BBC Dirac as new SMPTE VC-2 standard codec: http://www.bbc.co.uk/rd/pubs/whp/whp159.shtml More on HD: http://www.microsoft.com/windows/windowsmedia/ howto/articles/understandinghdformats.aspx EBU: HD image formats http://tech.ebu.ch/docs/techreview/trev_299-ive.pdf