Preservation content in_files

Preservation of Audiovisual Content
in Files
Richard Wright
SIPAD14, Mexico City, October 2014

preservationguide.co.uk 2Richard Wright
Overview
 digital preservation
 files and formats
 encodings and wrappers
 lossy compression, lossless compression,
uncompressed
 “OAIS and all that” – and how it applies to
audiovisual material, or doesn’t
 the new problems: risk goes up as storage cost goes
down; format obsolescence; general technology
obsolescence; survival strategies in a digital world

Overview -- Part two
 Access: this is the payoff of putting up with all the problems
of digital technology: instant free global access – to
everything! (Many examples given yesterday)
 A review of limits to access; limitations on:
 what we keep: increase in risk, increase in amount of content,
decrease in life of storage
 rights; secondary exploitation; public value licensing; legislation
 who gets in: mechanisms for access control: identity,
authorisation
 networks: cost, bandwidth
 tools for understanding storage and risks

Resources
 AV Digitisation and Digital Preservation TechWatch
Report #02
 https://prestocentre.org/library/resources/av-
digitisation-and-digital-preservation-techwatch-
report-02
 Digitising Contemporary Art D6.2 "Best practices
for a digital storage infrastructure for the long-term
preservation of digital files" Sofie Laier Henriksen,
Wiel Seuskens and Gaby Wijers (LIMA)
 //www.dca-project.eu/deliverables

Strategies for Survival

Stone, papyrus, film, hard
drive: what’s next?
Medium bits/cm² life, yr
Stone 10 10 000
Paper 104
1000
Film 107
100
Disc 1010
10
Each step: 1000 times cheaper, lasts 1/10th as
long
Soon? Infinite Zero

Infinite storage,
no persistence:
Photo: http://www.flickr.com/photos/chascar/476475563/
The
Cloud !

Direction of Technology
Storage is a service: PrestoSpace, 2004
A file is a performance: PrestoPrime, 2010
2014: Media without media
 Using managed services
 Managing managed services
 Statistics, trust, indemnity
 Advantage: storage provided by professionals;
archivists can do archiving (producers can produce,
curators can curate ...)

Stages in the life of AV content
 signal: audio from a microphone, video from a
video camera
 recording of a signal onto a carrier
 digitisation of a recording of a signal
 digital preservation of the digitisation of a
recording of a signal
UK Digital Preservation Coalition: Preserving
Moving Pictures and Sound (by R Wright)
http://www.dpconline.org/advice/technology-watch-
reports

Three kinds of AV content
 analogue
 digital on shelves
 CD, DVD, Blu-Ray
 audio: Minidisc, DAT
 video: DV, professional digital videotape formats
 preservation (ripping): make a clone (if possible)
 there are complications
 there are tools: eg DVAnalyzer
 http://www.avpreserve.com/avpsresources/tools/
 digital in files

Audiovisual Content is
Special
Technically demanding
Context: use in “scholarly
communication”
Interoperability
A Matter of Time
Wikimedia Common CC licence; author STEINDY

Special Technical Issues
 Audiovisual files are not just quantitatively different
from usual digital library files
 Size: 1hr HD video (uncompressed) = 800 GB
 Management: storage, movement
 Errors: 1 TB = 1012
; common disk error rates 10-13
 They are qualitatively different
 Wrappers – Quicktime (MOV), MXF, AVI, ...
 Composites: audio, video, subtitles, timecode ...
 Encoding and quality management issues

Special Contextual Issues
Use in Scholarly Communication:
 Citation
 Quotation
 Annotation
 Authority / Provenance
All our expectations are based on
writing, not on spoken word, audio,
film or video
The record of an event is the written
record. Why?
Wikimedia Common CC licence; author Piero

Special Interoperability
Issues
Europeana:
 Harvests OAI-PMH metadata
 Broadcasters never heard of OAI-PMH
 OAI never heard of time-based
metadata
 Storyboard representation (keyframes)
 Subtitles
 Time code
Digital libraries don’t do time-based
access – specific case of lack of
structured access

The time dimension
Europeana has a time dimension – divided into centuries
Audio and video use edit systems with timelines in
seconds, or fractions of a second
– and visual representations of content divided into units
(of some kind): the storyboard

Three Aspects of
Digital Preservation
 Making analogue content into digital content
 Digitisation (covered yesterday)
 Working with digital content
 Digital workflow and processes
 Preserving the digital content
 Digital Preservation

Three Aspects of
 1- Making analogue content into digital content
 Planning
 Budget
 Workflow
 Standards
 Rights
 Result: lots of files
 PrestoSpace information online:
//preservationguide.co.uk/RDWiki/
 Now: revised for PrestoCentre = //prestocentre.eu/

Three Aspects of
 2- Working with digital content (lots of files)
 Management
 DAM/MAM
 Repository
 Storage
 Metadata
 digital library technology
 Access
 Rights

Three Aspects of
 3- Preserving the digital content
 Keeping the data ‘forever’
 Coping with obsolescence
 Migration
 Emulation
 Standards: “OAIS and all that”
 Digital preservation technology
 Planning and strategy

Files and their formats
 (US) LOC has a guide to their preservation
www.digitalpreservation.gov/formats/intro/intro.shtml
 (UK) National Archive has format registry
PRONOM – and they archive software
www.nationalarchives.gov.uk/pronom/
 (Netherlands) National Library has emulation for
DOS, extending life of software (sort of)
http://dioscuri.sourceforge.net/
 Digital Library technology runs services on files:
JHOVE, DROID, metadata extraction

Digital Library Services
 Enable automation
 Of ingest
 File format identification DROID, JHOVE
 File validation JHOVE
 Metadata extraction
 National Library of New Zealand
 OAI-PMH protocol for metadata harvesting
 Of migration
 PLANETS ‘preservation planning’ methods

Why Automation?
 Portico (electronic document repository) has
ingested 9.1 million PDFs in a decade
 (and 800k had validation errors)
 How many files would the BBC send to an
asset management system per day, coming
from how many different applications?
 (1000 files from 100 applications?)
 Meaning a million in three years
 All of which need ingest, validation, preservation

DROID – UK National Archive
DROID (Digital Record Object Identification) is a software tool
developed by The National Archives to perform automated batch
identification of file formats.
DROID is designed to meet the fundamental requirement of any digital
repository
 to be able to identify the precise format of all stored digital objects
 and to link that identification to a central registry of technical
information about that format and its dependencies.
DROID uses internal and external signatures to identify and report the
specific file format versions of digital files. These signatures are stored
in an XML signature file, generated from information recorded in the
PRONOM technical registry.
New and updated signatures are regularly added to PRONOM, and
DROID can be configured to automatically download updated
signature files from the PRONOM website via web services.
DROID is a platform-independent Java application, and includes a
documented, public API, for ease of integration with other systems.

JHOVE: JSTOR/Harvard Object
Validation Environment
JHOVE provides functions to perform format-specific identification,
validation, and characterization of digital objects.
 Format identification is the process of determining the format to which
a digital object conforms; in other words, it answers the question: "I
have a digital object; what format is it?“
 Format validation is the process of determining the level of
compliance of a digital object to the specification for its purported
format, e.g.: "I have an object purportedly of format F; is it?"
Format validation: well-formedness and validity.
1. well-formed: it meets the purely syntactic requirements for its
format.
2. valid: it is well-formed and it meets additional semantic-level
requirements
.
 Format characterization is the process of determining the format-
specific significant properties of an object of a given format, e.g.: "I
have an object of format F; what are its salient properties?"

National Library of New Zealand Metadata
Extraction Tool
 Purpose: to programmatically extract preservation metadata from a
range of file formats
 Initially developed in 2003; open source in 2007.
 The Tool builds on the Library's work on digital preservation, and its
logical preservation metadata schema. It is designed to:
 automatically extracts preservation-related metadata
 output that metadata in a standard format (XML)
 Supported File Formats: the Metadata Extract Tool includes a number
of 'adapters' that extract metadata from specific file types. Extractors
are currently provided for:
 Images: BMP, GIF, JPEG and TIFF.
 Office documents: MS Word (version 2, 6), Word Perfect, Open Office
(version 1), MS Works, MS Excel, MS PowerPoint, and PDF.
 Audio and Video: WAV and MP3.
 Markup languages: HTML and XML

Architecture
Digital library services are generally:
 open source
 web service architecture
 reliant on metadata standards (schema) to work at
all
Do audiovisual archives need these services?
Can these services work (or be made to work) on
professional audiovideo files?

Encodings and Wrappers
 an MP3 file is MP3 encoded audio in an MP3 file
 BUT- MP3 could also be in an AVI file along with
video
 OR – MP3 could be in an MXF file along with video
(and the video could be in various encodings)
 Hence: when a file can hold various kinds of
encodings, and especially when a file can hold
multiple audio and video signals – we call it a
wrapper so that we can separate:
 the file type (eg AVI, MXF …)
 from the encodings of signals inside the wrapper

Lossy compression, lossless
compression, uncompressed
 Lossy data reduction should not be created by the
archive
 but if you’re given a lossy file, that’s your ‘artefact’
 Uncompress and save ‘whole’ when obsolescent
 DO NOT recode from one lossy format to another;
that becomes a ‘generation loss’
 Saving SD video ‘whole’ is cheaper than digibeta!
 Saving HD video ‘whole’ may be completely
unfeasible for several more years; shame

preservation of complex
objects (art!)
 if you’re given a lossy file, that’s your ‘artefact’
 if you’re given a ‘work’ – that’s also your artefact
 basic principle – preserve the artefact
 complex artefacts may not divide into ‘essence’ and
metadata (signals and metadata)
 migration becomes less and less satisfactory
 emulation (esp multivalent approach) may be much
more satisfactory
 Institutions need to maintain legacy ‘platforms’ – as
KB in The Hague is already doing (DOS)

Lossless “compression”
 For: saves on storage
 but how much is that as % of total dig archive cost?
 Against:
 adds a layer of complexity in creation (one off)
 adds a layer of complexity in playback (forever)
 slows down playback
 may tie you to proprietary software
 or even proprietary hardware!
 destroys the error-tolerance of an uncompressed
file

Bit rot – image examples
GIF: 3 bad bytes in 10k BMP: 160 bad bytes in 40k

File errors and file resilience
 Prof Manfred Thaller, Univ of Cologne and other
papers (eg Heydegger,2008)
 Example: image file with one bad byte
Format Size % of file affected
TIFF 10M 0.000 01
JPEG 3.8M 2.1
JP2K 7.3M 17
 State of the Art: uncompressed, or inter-frame
compression, with fixity check on each frame
(AVPS has guidance to fixity checks)

File Migration 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

Strong claim: the numbers representing the
uncompressed audio signal will never need to
change

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”

Video Roadmap
Preservation Roadmap:
Low: VHS, compressed digital DV file, 25 Mb/s
Middle: U-Matic, DV DV file
High: BetaSP, Digibeta, uncompressed or
other pro formats lossless compressed,
(JPEG2000 FFV1)

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

Recommended for Video

Professional: MXF; does everything

Alternatives: MOV (Quicktime), AVI

But: AVI does not support timecode

File Formats for Film

DPX uncompressed, very flexible

DCI DCDM = Digital Cinema Distribution Master:
2048x1080 (or 4096x2160) only

DCP = Digital Cinema Package = lossy compressed
JPEG200; (not for master)

JPEG2000 (lossless); 2:1 data reduction

Various lossy compression formats (avoid!)

And … various wrappers: MXF, AVI ...

Migration of File Formats
I s t h e f o r m a t a
p r o b l e m ?
S T A R T H E R E
A r c h i v e f o r a
f e w y e a r s
W h a t c o s t / q u a l i t y / r i s k
o p t i o n c a n y o u a f f o r d
C o m p r e s s
l o s s y
Y E S
N O
U n c o m p r e s sC o m p r e s s
l o s s l e s s
E N D H E R E
( 1 )
( 2 )
( 3 ) ( 4 )
( 5 a )( 5 b )
( 5 c )

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

One emulator: Univ of Liverpool Multivalent Browser

Strategy with Emulation
I s t h e f o r m a t a t
r is k ?
S T A R T H E R E
A r c h i v e f o r a
f e w y e a r s
W h a t c o s t /
q u a lit y / r is k c a n
y o u a f f o r d ?
C o m p r e s s
lo s s y
Y E S
N O
U n c o m p r e s s
C o m p r e s s
lo s s le s s
E N D H E R EM u lt iv a le n t

OAIS (& METS, MODS,
PREMIS …)

“OAIS and all that” – and how it
applies to audiovisual material, or
doesn’t
 Open Archive Information System is a concept for
tightening control over files, so that there is much
less risk of their loss
 “Trusted Digital Repositories” (TDRs) follow OAIS
(and various other principles)
 TRAC – methods for evaluation whether a TDR
deserves the label ‘trusted’
 Much information form DPE = Digital Preservation
Europe URL: www.digitalpreservationeurope.eu/

OAIS for audiovisual content:
 Some use in US public broadcasting
 Project WNET (with WGBH and NYU) (closed!)
 used Fedora digital repository software
 and METS, PREMIS, PBCORE (not MODS)
 PrestoPRIME implemented OIAS and other digital
preservation technology as a demonstration system
 partner: Ex Libris, Rosetta, New Zealand
 Many repositories now use OAIS “information packages” –
SIP, AIP, DIP; Archivematica is free and open-source
 Overall problem: content that is regularly changed

More on TRAC
 “The Trustworthy Repositories Audit & Certification:
Criteria and Checklist (TRAC), is the principle tool used
by CRL in its auditing and certification of digital
repositories. TRAC criteria measure the ability of a
given repository to preserve digital content in a way that
serves the repository's stakeholder community.”
 “TRAC metrics are based on the ISO 14721:2012
standard. This standard is commonly referred to as the
OAIS reference model”
 http://www.crl.edu/archiving-preservation/digital-
archives/metrics-assessing-and-certifying

More on TRAC
 The social, political and economic environment of a
Trusted Digital Repository
 TRAC Criteria Documents
A1.2 Contingency plans, succession plans, escrow arrangements
(as appropriate)
A3.1 Definition of designated community(ies), and policy relating to
service levels
A3.3 Policies relating to legal permissions
A3.5 Policies and procedures relating to feedback
A4.3 Financial procedures
A5.5 Policies/procedures relating to challenges to rights

More TRAC
B1 Procedures related to ingest
B2.10 Process for testing understandability
B4.1 Preservation strategies
B4.2 Storage/migration strategies
B6.2 Policy for recording access actions
B6.4 Policy for access
C1.7 Processes for media change
C1.8 Change management process
C1.9 Critical change test process
C1.10 Security update process
C2.1 Process to monitor required changes to hardware
C2.2 Process to monitor required changes to software
C3.4 Disaster plans

Levels of digital preservation
 NDSA = National Digital Stewardship Alliance
http://www.digitalpreservation.gov/ndsa/
www.digitalpreservation.gov/ndsa/activities/levels.html
protect
know
monitor
repair
 storage, fixity, security, metadata, file formats
 nothing specifically about audiovisual issues

Managing Digital Preservation
- a simple model (from Arkivum)

Digital: the new problems:
 risk goes up as storage cost goes down;
 format obsolescence;
 general technology obsolescence;
 survival strategies in a digital world

What will happen to storage:
 Capacity
 Cost
 Usage
 Risk
?

The Capacity Goes Up
1980 1990 2000 2010
Hard drive storage capacity
1000
10
0.1
0.001
Gigabytes

Moore’s Law
Originally – complexity of
integrated circuits
doubling every 18 month
But – memory in general
(RAM, disc, tape) has
followed the same ‘law’
Fred G Moore

The Cost Goes Down
Cost per gigabyte goes down: cost reduction for storage
has been faster than Moore’s Law since 1990

The Usage Goes UP

The Risk Goes Up Too
Device reliability has increased
– but the number of devices in use has greatly increased

Risk, Devices and Reliability
 Risk of loss of data:
 proportional to number of devices
 and to the size of the devices (because each holds
more data)
 and the complexity of storage management (unless
somehow complexity can be used to reduce risk)
 and … to reliability of individual devices

Risk, Devices and Reliability
 Many more risks besides loss of storage devices
 format obsolescence
 IT infrastructure obsolescence
 file corruption
 system corruption
 errors and other human actions
 Which all increase in significance (impact) in
proportion to the amount of storage in use

Conclusion:
As storage gets really cheap
… it gets really risky.

format obsolescence;
general technology
obsolescence;
 OAIS is meant to provide an overall structure that is
entirely independent of implementation technology
 None of this technology has really been proven!
 (and I’m still worried about storage failures and bit
rot)
 ‘continuous migration’ is one answer to all forms of
obsolescence (if always done in time)

Survival Strategies: Prevention
of loss
 Where most of the attention (and research) is
directed:
 reducing MTBF for devices
 making copies !
 using storage management layer(s)
 introducing virtual storage layer(s)
 using Digital Library technology
 OAIS ‘packages’
 preservation metadata (PREMIS)

Limits
 Technology: gets better – and worse – at the same
time
 Rights; secondary exploitation; public value
licensing; legislation
 Who gets in: mechanisms for access control:
identity, authorisation
 Networks: cost, bandwidth
 Who doesn’t have Internet?

Limits: Technology
Medium bits/cm² life
Stone 10 10 000
Paper 104
1000
Film 107
100
Disc 1010
10
=> Each change 1000 times cheaper, but lasts 1/10th
as long

Limits: Rights
 See Nan Rubin paper (IFLA-PAC)
 http://www.ifla.org/files/assets/pac/ipn/47-may-
2009.pdf
“Not having clear permission to reuse older programs is
a primary factor that discourages public television
from making an investment in long-term program
preservation. Until rights agreements are improved,
archival content will remain largely inaccessible.”
 BBC Creative Archive – used a version of a Creative
Commons licence

Limits: Access Mechanisms
 Academic use can be an ‘exception’ to copyright
 Academic institutions use controlled networks
 Shibboleth is an emerging global standard (W3C)
for access / identification (in academia)
 Who supports identification of the general public?

Limits: Networks and Cost
 Network charges cost more than storage charges in
BBC Open Archive trial
 BUT – solved (?) by YouTube

Four requirements
for sensible access
 Granularity
 Navigation
 Reference and Citation
 Annotation

Granularity - division into
meaningful units
 Keyframes
 Other methods to represent video
 and audio:

Navigation
 "Click and play" on visual representation of the
meaningful units

Reference and Citation
 the core requirement for scholarly discourse
 along with a major change in attitude!
 Needs a permanent place for “things to be”
 Hence the need for stable audiovisual collections
“Hamlet, for example, is comparable to Saxo
Grammaticus' Gesta Danorum.[citation needed]
King Lear is based on King Leir in Historia
Regum Britanniae by Geoffrey of Monmouth,
retold in 1587 by Raphael Holinshed.[citation
needed]
“
wikipedia

Annotation
 the core requirement for social
web = interactivity
 individual interacts with content
 individuals interact with other
individuals

Limits: who doesn’t have
Internet
Africa check your users

Managing Digital Preservation
- a simple model (from Arkivum)

And now:
one PrestoPRIME tool
 A model for storage systems, to calculate
 Cost
 Risk
 Loss
 And compare what-if scenarios
 Storage model: http://prestoprime.it-
innovation.soton.ac.uk/planning-tool/

Storage Systems
HDD in servers
Migration required every 4 years. Running Costs
Access: €0.1 per GB
Storage: €1 per GB per year
Corruption Rates
Access: avg. 1 in 500 files
Latent: avg. 1 in 750 files per year
HDD on shelves
Access: €1 per GB
Storage: €0.25 per GB per year
Corruption Rates
Access: avg. 1 in 100 files
Latent: avg. 1 in 500 files per year

More Storage Systems
Data tapes in a robot
Access: €0.2 per GB
Corruption Rates
Access: avg. 1 in 1x104
files
Latent: avg. 1 in 1x105
files per year
Data tapes on shelves
Access: €1 per GB
Corruption Rates
Access: avg. 1 in 1x104
files
Latent: avg. 1 in 1x105
files per year

Storage Configuration
Found 3 storage configurations. Add...
Disk with Tape
System 1: HDD in servers
Files accessed avg of 0.25 times per year, staying
constant
Scrubbing every 1 year(s)
System 2: Data tapes in a robot
Files accessed avg of 0 times per year, staying
constant
Scrubbing every 3 year(s)

File Collections
 Found 1 file collection. Add...
 read-only
 Default File Collection
 Length of cost/loss projection is 25 year(s). Files
 100 thousand initially, staying constant.
 Average File Size
 25 GB.

Plans
Found 3 plans. Add...
Disk and Tape edit Delete Evaluate
File Collection: Default File Collection
25 year lifetime. 100 files, avg. 25 GB in size.
Storage Configuration: Disk with Tape
Uses HDD in servers and Data tapes in a robot
systems.

Thank You
 Storage model: http://prestoprime.it-
innovation.soton.ac.uk/planning-tool/
 PrestoCentre prestocentre.eu
 Richard Wright preservation.guide@gmail.com
preservationguide.co.uk

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