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Studies FY2008

The themes of studies FY2008 are as follows:

(1) Study on digitization of analog audio-visual materials

A comparative study on specifications to digitize analog audio-visual materials for each purpose (for preservation and for distribution) was conducted.
The NDL conducted trial digitization of its holdings of analog audio-visual materials and compared the sound and image quality by listening to or viewing each digital file.

Audio materials

The target materials are the following:

  • Cassette tapes
  • Open reels

Table 1 shows the conditions for digitizing audio materials for preservation and for distribution.

Table 1: Conditions for digitizing audio materials
Usage File Format Sampling Rate Bit Depth Bit Rate
Files for preservation WAV(.wav) 48kHz 16bit -
96kHz 24bit -
192kHz 24bit -
AIFF(.aif) 48kHz 16bit -
96kHz 24bit -
192kHz 24bit -
Files for distribution MP3(.mp3) - - 128kbps
- - 320kbps
WMA(.wma) - - 128kbps

Visual materials

The target materials are the following:

  • VHS (Video Home System)
  • Betamax videocassettes
  • U-matic videocassettes
  • LD (Laser Disc)
  • VHD (Video High Density Disc)
  • Motion picture films (8mm/16mm)

Table 2 shows the conditions for digitizing visual materials for preservation and for distribution.

Table 2: Conditions for digitizing visual materials
Usage File Format Container Bit Rate Rate Control Audio Codec
Files for preservation MPEG-2 MPEG-2 PS (.mpg) 9Mbps CBR* LinearPCM
9Mbps VBR**
50Mbps VBR
MPEG-4 AVC Matroska (.mkv) 9Mbps CBR
9Mbps VBR
50Mbps VBR
Files for distribution Flash Video On2 VP6 Flash Video (.flv) 300kbps CBR MP3
MPEG-4 AVC MPEG-4 AVC (.mp4) 300kbps AAC
Windows Media Video Windows Media (.wmv) 300kbps WMA

*CBR (Constant bit rate)
**VBR (Variable bit rate)

The results of the study showed the difficulty of determining uniformly the most appropriate specifications for all kinds of audio/visual materials and the need to develop a policy on the level of required quality of digital files, considering factors such as physical condition of original materials and cost-effectiveness.

(2) Trial migration of 5.25-inch floppy disks (FDs)

The NDL holds a number of 5.25-inch FDs, which are deteriorating physically over time. Therefore, the NDL conducted migration[*] of data from 5.25-inch FDs to a hard disk on a trial basis.

[*] Migration means to transfer data to a new recording medium or convert data format so as to ensure the long-term accessibility of the data. For details, please see "What is "migration" and "emulation"?" in the FAQ.

The migration was carried out in two stages. First, the data was transferred from 5.25-inch FDs to 3.5-inch FDs with a dedicated data converter, because a data converter reading data directly from 5.25-inch FDs was not easily available and the production of dedicated external FD drivers had already stopped. Next, files transferred to each 3.5-inch FD were converted to one image file and stored in the hard disk.

As a result, about 86% of them were successfully migrated.

The NDL's study on migration of FDs has been under way since FY2006. Please also see Studies FY2006 and Studies FY2007.

Other FY2008 activities

The NDL made a pilot assessment of the Digital Library from the Meiji Era in terms of long-term preservation of digital contents with DRAMBORA (Digital Repository Audit Method Based on Risk Assessment).

DRAMBORA is a toolkit to facilitate internal audit by providing repository administrators with a means to assess their capabilities, identify their weaknesses, and recognize their strengths, jointly developed by the DCC (Digital Curation Centre) and DPE (Digital Preservation Europe).

The NDL translated DRAMBORA ver. 1.0 into Japanese.

For details, please see the news of "DRAMBORA Translated into Japanese" in the DRAMBORA website.

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