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Studies FY2006

The themes of studies FY2006 are as follows:

(1) Study on specifications and playback equipment of audio-visual materials

To obtain basic information on digitization of obsolete audio-visual materials whose future use is uncertain due to deterioration of its recorded media and playback equipment and obsolescence of their specifications, their specifications and technical requirements were studied.

The availability of playback equipment of such materials as of March 2007 was also looked into. According to the results, many devices proved to be available only to a limited extent or have already become unobtainable, while some kinds such as record players were still available.

(2) Study on A/D conversion (conversion from analog to digital) of audio-visual materials

For digitizing audio-visual materials to ensure their long-term availability, we conducted the following research.

Hardware and applications used for A/D conversion

Firstly all devices which can be utilized for A/D conversion were picked out mainly from professional-use products offered commercially. Secondly, software for format conversion of digital data corresponding to each device was studied.

Conditions for A/D conversion

Referring to the conditions in which a born-digital resource is initially recorded as digital data, we clarified conditions of A/D conversion which do not worsen the sound and video quality of the original materials and currently possible techniques to restore resources whose sound and video pictures are deteriorated. For sorting out the conditions of A/D conversion, we worked out literature research and interviews, focusing on

  • sampling rates and quantization bit rates, etc.,
  • measures for denoising and perspective on it,
  • measures for control of volume and sound pressure,
  • response to division between recorded tracks.

Conversion method of deteriorated materials

We classified major physical deteriorations by recording media and sorted out conservation methods for each case.

File formats for long-term preservation after digitization

For each file format below, which is adopted as de facto standard or international standard owing to its popularity, we studied its characteristics, potential, playback applications and others by literature research and interviews.

(Audio data)
WAV, MPEG-4 ALS, MPEG-1 Layer 1, MPEG-1 Layer 2, MPEG-1 Layer 3 (MP3), MPEG-2 BC, and MPEG-2 AAC
(Visual data)
AVI, MPEG-1, MPEG-2, MPEG-4, MPEG-4 AVC/H.264, Motion JPEG2000, D-1 VTR, Digital BATACAM, and DVCAM

We also examined, for audio data and visual data, relationships between bit rates per unit of time and quality / resolution, and did a trial calculation of file size by quality.

Digitization of information on packages (jackets)

We conducted literature research and interviews on tools for loading metadata, such as song title, name of singers, composers and lyricist, from package (jacket) and lyric sheet as digital data, and for assigning metadata to each digitized song. We found that the OCR is generally used at present.

Metadata describing the method of A/D conversion

Considering metadata items to indicate the process of digitizing analog materials and converting them into file formats appropriate for long-term preservation, we classified roughly into three groups as follows:

  • elements about original materials (medium, recording method, etc.),
  • elements about digitized materials (file format, compression method, file size after compression, etc.),
  • elements about digitization (date of digitization, equipment, application, conditions of A/D conversion, etc.).

Calculation of work hours for digitization

Based on the above-mentioned study results, we envisaged a standard digitization process in the NDL and calculated work hours for each stage.

(3) Study on migration of FDs

For FDs, which are particularly becoming technically obsolescent and will possibly be unusable in future among recording media for digital information, the following research was carried out.

Major specifications of FDs

Size, memory density, format specifications and others were studied. At the same time, FD specifications compatible to major playback equipment were also studied.

Equipment and tools (software) required for migration

Through literature research and interviews with experts (including vendors), we studied migration tools (software) applicable to a wide range of FD specifications and required equipment for migration using such tools.

Restoration methods

Measures in cases where data are not readable due to handling and storage conditions were examined.

File formats after migration

Based on the experimental operation of tools creating images treated in the above-mentioned study on equipment and tools required for migration of FDs, we analyzed the results and sorted out file formats for the respective tools.
In addition, using FD samples from the NDL collections, we executed the migration in order to clarify the problems. 85% of them were successfully migrated.

“FY2006 Study Report on Long-term Accessibility of Digital Information”, March 2007


  1. Outline
    • 1.1. Background and purpose
      • 1.1.1. Background
      • 1.1.2. Purpose
    • 1.2. Outline
      • 1.2.1. Study on digitization of audio-visual materials
      • 1.2.2. Study on migration of FDs
  2. Study on specification and playback equipment of audio-visual materials
    • 2.1. Study on specification and technical requirements
      • 2.1.1. Specification and technical requirements of audio materials
      • 2.1.2. Specification and technical requirements of visual materials
    • 2.2. Study on availability of playback equipment
      • 2.2.1. Outline
      • 2.2.2. Results
      • 2.2.3. Availability of playback equipment and future tasks
    • 2.3. Future tasks concerned with studies on specifications and technical requirements of obsolete audio-visual materials
  3. Study on A/D conversion of audio-visual materials
    • 3.1. Study on equipment and system for A/D conversion
      • 3.1.1. Outline
      • 3.1.2. Results
    • 3.2. Study on conditions for A/D conversion and conversion method of deteriorated materials
      • 3.2.1. Outline
      • 3.2.2. Results
    • 3.3. Study on file formats for long-term preservation
      • 3.3.1. Outline
      • 3.3.2. Results
    • 3.4. Study on digitization of information on packages (jackets)
      • 3.4.1. Outline
      • 3.4.2. Results
    • 3.5. Study on metadata
      • 3.5.1. Outline
      • 3.5.2. Results
    • 3.6. Study on cost of digitization
      • 3.6.1. Outline
      • 3.6.2. Results
    • 3.7. Future issues concerned with A/D conversion of audio-visual materials
      • 3.7.1. Future issues concerned with preservation after digitization
      • 3.7.2. Future issues concerned with digitization of information on packages
      • 3.7.3. Metadata and future tasks
    • 3.8. References
  4. Study on migration of FDs
    • 4.1. Study objects
    • 4.2. Study on FD specifications
      • 4.2.1. Outline
      • 4.2.2. Results
    • 4.3. Study on equipment and tools (software) for migration of FDs
      • 4.3.1. Outline
      • 4.3.2. Results
    • 4.4. Study on file formats after migration
      • 4.4.1. Outline
      • 4.4.2. Results
    • 4.5. Analysis of migration of sample FDs
      • 4.5.1. Purpose
      • 4.5.2. Outline
      • 4.5.3. Results
      • 4.5.4. Analysis
      • 4.5.5. Future tasks
    • 4.6. Future tasks concerned with migration of FDs

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