Digitizing the Collection
The majority of paper items were scanned by the Library's ITS Digital Scan Lab. An uncompressed TIFF scan of the original archival item with no compression was made. High resolution scans were made in color, with a few exceptions, at 24 bits-per-pixel and 300 dpi using the Phase-one FX camera. Derivative Truecolor images were made from the TIFF files by Library of Congress Network Development staff. The digital images online are jpeg images (quality level 80) in 5 sizes with an average compression ratio of 10:1 (the compression ratios may vary slightly depending on the size of the derivative).
Audio files are available as MP3 files or as RealMedia streaming files. The files were made from original source materials including recorded discs (78s and lps), tapes, and compact discs.
Discs - Discs were played on professional-quality Technics turntables, every effort being made to use the optimum stylus and playback speed. The signal went through a pre-amp and onto DAT. Sound was transferred from DAT to computer and saved as WAV files at 44.1K/16-Bit. The EQ was adjusted with Sound Forge 5.0, usually by cutting high-end frequencies with no musical content (This varies from disc-to disc). The files were then de-clicked, amplified, and beginnings and ends faded using Cool-Edit Pro 1.0. The derivative files were generated using Sound Forge 5.0., the MP3s at 96K, the RealMedia files at 56K.
Some discs did not track completely with one playback. Various methods were employed to capture all the sound, and the performance was reconstructed in the digital domain, usually with Sound Forge 5.0. On some early discs, playback speed was inconsistent. To the extent that this could not be compensated for by adjustments during playback, Diamond Cut Millennium Edition was used to achieve a more consistent pitch.
Tapes - Tapes were played from high-quality Studer tape-decks directly to DAT. The rest of the process is similar to disc transfers, except that de-clicking was seldom needed.
CDs - CD tracks were ripped using Sound Forge 5.0. Amplification, edits, and fades were also performed with Sound Forge.