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Digital Library Center
Smathers Libraries
University of Florida
P.O. Box 117007
Gainesville, FL32611-7007 USA

P: 352.273.2900
F: 352.846.3702
DLC@uflib.ufl.edu

Digital Library Center: Audio/Video Sampling and Capture for Digital Preservation

Standards for audio sampling/capture are:

  • Current standard: 24-bit 96.0 kHz WAV
    (An hour of audio at this standard is 1.98 GB.)
  • Old standard: 16-bit 44.1 kHz WAV

Video Standards for Encoding:

  • Ideal: HD Standard (1080p preferred over 1080i)
  • Acceptable: NTSC (525-line, 30 frames per second, interlaced)

Video Standards for File Formats:

  • Ideal: MPEG-4
  • Acceptable: MPEG-2
  • Acceptable deriviatives are WMV, AVI, QT

Technology is moving toward 24-bit 192 kHz. For the moment, we do not to use this standard. While the technical capability is now available, it has not yet been adopted by the various audio engineering associations. Technology is also moving toward variable bit rate (VBR) encoding. For the moment, we have chosen to stay with the constant bit rate (CBR) encoding. VBR is reported to reproduce recorded sound more faithfully, but it introduces archive issues not yet addressed (to our knowledge) by digital library archives.

DLC Current A/V Processing

Current video processing is done using:

  • Standard Intel Core 2 Duo machine with 2 GiB of RAM base
  • ATI All-in-Wonder 2006 Edition (Radeon X1300 GPU); PCI-e
  • YPrPb adapter, TV-Tuning capabilities (and capture), HD-ready output.

We can capture video from a JVC SuperVHS unit and convert the analog signal to a usable, preservable digital signal with a minimum of interference (versus using an external decoder).

We encode in MPEG-2 and AVI (AVI used for downloading, MPEG-2 or 4 for preservation on optical media). Three resolutions standard: 320x240, 640x480, and 720x480. Depending on the source, we can’t always dictate whether something can transformed into HD. NTSC, 30fps is acceptable, mostly when it comes to objects drawn from video tape (especially amateur productions on consumer-grade cassettes). We use Adobe Premier Elements 2.0 for video encoding.

Current audio processing is done using the same computer with a specialized sound card, using the component audio software and Audacity freeware as a supplement. We also use a dual tape deck, depending on specific project needs.

Distribution Formats

Most audio players do not yet play either 24-bit or 96 kHz audio. Most players support 16-bit audio, some support 44.1 kHz while others only 28 kHz. For distribution, we down-sample the archived audio to the CD audio standard, 16-bit 44.1. The cleaned voice-audio signal should experience no degradation to lower than 28 kHz, per the research. The DLC plans to distribute the following formats:

  • CD/DVD audio (for distribution to Special Collections and/or applicable department)
  • Streaming MP3 (for Internet distribution) MP3 seems to be the prevailing Internet streaming and download format.

Resources

Printing

If image materials are to be printed at a large size using the Map Library's printer, the files need to be under a maximum of 180MB. Also, backgrounds should be white or light so as not to use too much ink.

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