# Presentation: 272508

## The Library of CongressAudio-Visual Prototyping Project 

- Carl Fleischhauer   (cfle@loc.gov)
- Office of Strategic Initiatives, Library of Congress
- Sound Savings Conference
- University of Texas, Austin
- July 25, 2003
- This slide show: lcweb.loc.gov/rr/mopic/avprot/SoundSavings03.ppt

## National Audio-Visual Conservation Center

- New Library of Congress facility for the Motion Picture, Broadcasting, and Recorded Sound Division (M/B/RS)
- Facility funded by the Packard Humanities Institute
- Will be in Culpeper, Virginia, 70 miles from Washington
- Planned to go operational 2005

## Audio-Visual Prototyping Project

- Collections from the M/B/RS division and the American Folklife Center at LC
- Emphasis: reformatting endangered materials, especially magnetic tapes and instantaneous discs
- Current work: audio
- Future activities: video, copyright MP3s, content from web sites
- Prototyping period: 1999-2004

## Motive 1: Alternative Preservation Approach 

- Shortcomings of conventional practice: reformatting onto analog magnetic tape
-   Short life expectancy
-   Generation loss with each copy
-   Cessation of manufacture of analog tape and tape recorders

## Motive 1: Alternative Preservation Approach 

- Desire to work in the digital realm
- Emerging issues
- Deterioration of *tangible* born-digital, e.g., CD-Rs acquired by LC from music composer copyrights
- Emerging issue: preserving *intangible* born-digital content, e.g., MP3s from copyright and other acquisitions

## Motive 2: Provide Access

- Limited access, since most items protected by copyright or require consideration of folk performer prerogatives
- LC researchers on Capitol Hill,  collections in Culpeper
- Possible future authorized remote research sites

## Illustration: sample preserved item

- We want to reproduce the artifact as a whole
- This example is a Marine Corps recording from the South Pacific in WW II
- Audio from a disc copy of an Amertape Recording Film original (film-with-grooves)
- Images depict the film container and the disc label

## Initial display of navigation tree and thumbnails

## Close-up display of image & file-level metadata

## Preservation Concept

- Content takes the form of *information packages* aka *digital objects*
- Information packages consist of *data* (e.g., audio and image files, ) and *metadata*

## Preservation Concept

- Not a CD or DVD approach
- Packages managed in digital repository
- Repository is server and storage-system based
- Paradox:
- Content at any given moment *depends upon* systems and media
- Content must be *system and media independent*

## Four issues

**1.**  ***Selecting the target format*** for reformatting
**2.** ***Quality of the reformatted copy***
**3.** ***Shaping the object/package***** **and the importance of ***metadata***
**4.  *****Longevity*** in “media-less” environment

## Issue 1Selecting the format

## Selecting the format

- Disclosure
- are specifications and tools available?
- Adoption
- is the format already in wide use?
- Transparency
- is encoding open to analysis with basic tools?

## Selecting the format

- Self-documentation
- does object include metadata that explains how to render or understand context?
- Fidelity
- support for high resolution audio
- Sound field
- support for stereo and/or surround sound

## Audio formats

- Audio masters
- Bitstream: PCM sampling, uncompressed
- File format: WAVE (higher res)
*One-bit-deep formats (e.g., SONY DSD) of interest but “ahead of the game” *for us
- Service files
- WAVE (lower res) and MP3

## Image formats

- Image Masters
- Bitstream: Uncompressed bitmapped
- File format: TIFF
- Service copies
- JPEGs

## Issue 2Quality of theReformatted Copy

## Key Parameters

-  Sampling frequency
- Render the waveform as “dots”
- More dots contribute to greater accuracy, capable of rendering high frequency sounds
- Expressed as kilocycles per second or kiloherz
*Compare to spatial resolution for images*
*Higher “pixels or dots per inch” contribute to better clarity*

## Key Parameters

-  Word length, bit depth
- Greater bit depth means greater precision in locating the sample in terms of amplitude
- Greater bit depth means greater capacity to represent dynamic range
- Expressed as bits per sample
*Compare to tonal resolution (color) for images*
*Higher “bits per pixel” mean more accurate color*

## Staff discussion of parameters . . .

- Consensus on word length
- Everyone is sold that 24 bit is better than 16
- Based on listening, objective measurement possible
- “Extra data will protect you when the original has wide or varying dynamics, or if an operator makes a mistake.”
- Compare to imaging and a *downstream* benefit
*Master image at 12 or 16 bits per channel*
*Manipulate for aesthetic effect, save at 8 bits*
*No gaps in your histogram*

## Staff discussion of parameters . . .

- Less consensus on sampling frequency
- Some of us thought this was the relevant question:  “What is the range of frequencies we might expect in this item?”
- 78 rpm disc from the acoustic era
- 8-10 kilocycles per second, or less
- Rule of thumb: digitally sample at 2x frequency
- Will 25 kilocycles per second suffice?
- Folk music collector with a Nagra in 1970s
- 14-18 kilocycles per second
- Will 44 or 48 kilocycles suffice?

## Staff discussion of parameters . . .

- Engineers advocated sampling frequencies of 96 or even 192 kHz
- Discussion tended to look at _practical production issues_ and possible _downstream_ options
- Objective measurement is not relevant to some of these factors

- Very high resolution desired because:
- “There may be hard-to-hear harmonics that you won’t want to lose.”
- “Copies with less noise and less distortion can more successfully be restored in a post-process.”
- “In the future we’ll have better enhancement tools and post-processing, so save as much raw information as you can.”
- “What if you need extra data to support certain types of resource discovery?”

- Staff discussion of parameters . . .

## Staff discussion of parameters . . .

- Inherent fidelity of the original items not decisive.
- Informal A-B listening comparisons were helpful but not conclusive.
- Proposal to carry out empirical comparison of restoration actions applied to a high-res and a medium-res master.

## Audio resolution for prototyping project

- Result of preceding discussion: the engineers work at the upper limit of the tools they have
- Reformatted content
- Audio masters
- 96 kHz/24 bit mono or stereo (some at 48/24)
- Service files
- 44.1 kHz/16 bit WAVE
- 256 kbps MP3 (if stereo)

## Image resolution for prototyping project

- Reformatted content
- Borrow approach from other digitization projects
- Image Masters
- 300-400 lines/pixels per inch
- 24 bit color
- Service copies
- Same-size JPEGs

## Two Sidebars

## Sidebar on practices

- Professional equipment
- For example, professional analog-to-digital converters
- Some details
- Masters as flat transfers, avoid/minimize cleanup
- Copy mono discs with stereo cartridge, hope for future process to “find the best groove wall”

## Sidebar on practices

- Professional workers
- Supervise and perform expert work
- Work requires knowledge and skills with antique formats and new digital technology

## Sidebar on practices

- Some ideas for the future
- Include apprentice workers in work team
- Sort originals by “transfer efficiency” category
- Use expert systems to help monitor transfers, spot anomalies
- For some categories, copy two or three items at once
- Inspired by
- PRESTO project in Europe (http://presto.joanneum.ac.at/index.asp)
- Image-based recovery from discs (http://www-cdf.lbl.gov/~av/)

## Sidebar on objective measurement

- Imaging: targets
- Audio: test tones
*Outputs from targets/tones measure the performance of equipment*
*They do not measure actual “content” images or sounds directly.*

## Sidebar on objective measurement

- Tools and practices not mature, even for imaging
- Need *performance measures* for digital systems
- You can’t believe your scanner when it says 300 ppi
- Measure what actually comes through the system
- Imaging example: use modulation transfer function (MTF) as a yardstick for delivered spatial resolution
- Pass-fail point not yet established for image reformatting projects

## Sidebar on objective measurement

- Tentative use of standard ITU test sequences known as CCITT 0.33
- 28-second series of tones to test satellite broadcast transmissions, mono and stereo
- Recordings of the tones can be used to determine the frequency response, distortion, and signal-to-noise ratio produced in a given recording system
- Pass-fail point not yet established for sound reformatting projects

## Issue 3Shaping the information package and the importance of metadata

## Information package

- Complex entity with multiple parts
- Data and Metadata
*Data* in this context means the *audio, video, *or*  image bitstreams*
- Metadata includes
- Descriptive
- Administrative
- Structural

## Descriptive metadata in the AV project 

- For object as a whole
- Often copy of descriptive data in LC central catalog
- MODS XML schema
- http://www.loc.gov/standards/mods/
- Optional additional descriptive metadata for individual parts of object
- Song titles, artists for disc sides or cuts
- Names of writers in manuscript file folder** **
- MODS “related items”

## Administrative metadata in the AV project 

- Persistent identifier, “ownership” info
- Documentation of reformatting today and digital migration tomorrow
- About the source and actions taken to prepare items for digitization, e.g., clean, bake
- About the digitizing process
- Rights data or at least categorization of objects for management of access

## Structural metadata in the AV project 

- Relationships between parts of objects
- Example: long-playing record album
- Box, front
- Three discs, two sides each (audio segments)
- Disc label (images)
- Booklet, cover and 28 pages (images)

## Illustration: three-lp-disc boxed set with booklet

## Encoding the metadata

- AV project is using the emerging Metadata Encoding and Transmission Standard (METS)
- http://www.loc.gov/standards/mets/

## METS XML output (partial) displayed in Internet Explorer

## Added metadata for long-term preservation

- To support long term content management
- Examples:
- “Fixity” info, e.g., checksums to monitor file changes
- Pointers to documentation for file formats
- Pointers to documentation of the hardware/software environment required to render files
- No practice yet in AV prototyping project
- See RLG-OCLC preservation metadata report
- _[http://www.](http://www.oclc.org/research/pmwg/)__[oclc](http://www.oclc.org/research/pmwg/)__[.org/research/](http://www.oclc.org/research/pmwg/)__[pmwg](http://www.oclc.org/research/pmwg/)__[/](http://www.oclc.org/research/pmwg/)_

## Overall anxiety . . . 

- Are we trying to capture *too much* metadata?
- Tools to automate the creation of metadata, especially administrative metadata, are critical

## Issue 4Longevity in amedia-less environment

## Future LC repository

- Intersection of the AV project and Culpeper center with LC-wide digital planning (NDIIPP)
- LC repository design will be in terms of the NASA Open Archival Information System (OAIS) reference model

## Reference Model for an Open Archival Information System (OAIS)

**P**
**R**
**O**
**D**
**U**
**C**
**E**
**R**
**S**

- ADMINISTRATION

- DATA
- MANAGEMENT

- ARCHIVAL
- STORAGE

- INGEST

- ACCESS

**C**
**O**
**N**
**S**
**U**
**M**
**E**
**R**
**S**

- PRESERVATION PLANNING

- Reference Model for an Open Archival Information System (OAIS)

**SIP: Submission information package**

## Reference Model for an Open Archival Information System (OAIS)

**P**
**R**
**O**
**D**
**U**
**C**
**E**
**R**
**S**

- ADMINISTRATION

- DATA
- MANAGEMENT

- ARCHIVAL
- STORAGE

- INGEST

- ACCESS

**C**
**O**
**N**
**S**
**U**
**M**
**E**
**R**
**S**

- PRESERVATION PLANNING

- Reference Model for an Open Archival Information System (OAIS)

**AIP: Archival information package**

## Reference Model for an Open Archival Information System (OAIS)

**P**
**R**
**O**
**D**
**U**
**C**
**E**
**R**
**S**

- ADMINISTRATION

- DATA
- MANAGEMENT

- ARCHIVAL
- STORAGE

- INGEST

- ACCESS

**C**
**O**
**N**
**S**
**U**
**M**
**E**
**R**
**S**

- PRESERVATION PLANNING

- Reference Model for an Open Archival Information System (OAIS)

**DIP: Dissemination information package**

## Reference Model for an Open Archival Information System (OAIS)

**P**
**R**
**O**
**D**
**U**
**C**
**E**
**R**
**S**

- ADMINISTRATION

- DATA
- MANAGEMENT

- ARCHIVAL
- STORAGE

- INGEST

- ACCESS

**C**
**O**
**N**
**S**
**U**
**M**
**E**
**R**
**S**

- PRESERVATION PLANNING

- Reference Model for an Open Archival Information System (OAIS)

**Current plan: The Culpeper facility will **
**  ****produce and  submit  packages to LC’s  future  digital repository. **

## While we wait for the OAIS-compliant repository . . .

- Continue to use UNIX-filesystem based storage
- Orderly file storage, masters segregated from service copies
- METS metadata stored for now as individual XML files
- Virtual information packages are “ready to submit”
- METS also supports end-user display

## What about smaller archives and libraries?

- The digital approach to content preservation depends on significant computer infrastructure
- Will we have a few consortial repositories to serve many smaller archives?
- Who and how would such arrangements be made?

## What about smaller archives and libraries?

- Holding action?
- For audio, make multiple CD-Rs or      DVD-Rs?  Write to data tape?
- LC is challenged to give good advice today

## Web Sites

- _[LC audio-visual prototyping project](http://lcweb.loc.gov/rr/mopic/avprot/avprhome.html)_
- http://lcweb.loc.gov/rr/mopic/avprot/
- _[LC enterprise-wide digital preservation planning](http://lcweb.loc.gov/standards/metadata.html)_
- http://www.digitalpreservation.gov/ndiipp/
- _[Metadata Encoding and Transmission Standard (METS)](http://www.loc.gov/standards/mets)_
- http://www.loc.gov/standards/mets/

## Thank you . . .