Surface Profiling Technologies Applied to Recorded Sound Preservation and Access
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Surface Profiling Technologies Applied to Recorded Sound Preservation and Access Lawrence Berkeley National Lab
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Surface Profiling Technologies Applied to Recorded Sound Preservation and Access. Lawrence Berkeley National Lab. The basic approach is to use optical measuring and image processing methods to create a digital representation of the complete record - PowerPoint PPT Presentation
Transcript of Surface Profiling Technologies Applied to Recorded Sound Preservation and Access
Surface Profiling Technologies Applied to Recorded Sound
Preservation and AccessLawrence Berkeley National Lab
The basic approach is to use optical measuringand image processing methods to create adigital representation of the complete record surface, on the computer, and then “play” it with a virtual needle.
Non-Contact Digital Imaging• Preservation
– Protects samples from further damage– Repair existing damage and debris through digital “touch-up”
• Access– Offload many aspects of transfer to automated software– Handle diverse formats
A “smart” copying machine for records
Micro-photograph of shellac disc:A two dimensional image “2D”can measure lateral grooves.
Surface profile of a wax cylinder:A three dimensional image “3D”is required for vertical cut groovesor to extract maximal information.
127-254 microns
de
ridge
valley
150 m400 m
Cylinder surface
Disc surface
3D Scan of an Edison Cylinder
cylinder
rotating stage
3D optical probe
translating stage
Measured dataReconstruction of groove profile in highlighted region.Data shown is measuredwith the STIL probe.
Supported by the Library of Congress and the Mellon Foundation
2) Acquire sequential axial scans
3) Overall cylinder shape is due to off-center, deformation, heard as low freq rumble
4) Subtract valleys from ridges to correct for overall shape
1) Sample at 96KHz to minimize effect of aliasing
(Ridges provide (approx),geometrical reference)
d/dt
5) Numerical differentiation to Calculate stylus velocity
Sound Comparison
• The Holy City, composed by Stephen Adams,
The Edison and Skedden Mixed Quartet, Amberol 1601
• Stylus*
• Optical (flat EQ)
• Optical + filter + re-EQ**
*Stylus version is from a modern “Archeophone” electrical cylinder player, flat EQ** Low frequency boost to compensate for acoustic horn performance
Damaged Wax Cylinders
• The recovery and restoration of damaged recordings is of great interest to the archives.
• Examples:– Cracked or broken: reassemble digitally– Surface mold (fungus) growth: pick good regions– Overall deformations: global shape fits
• Study of damaged media is a research priority for our project.– Current activity is to study wax dictation cylinders
from the estate of American author Jack London 1876-1916
Damaged Wax Cylinders
..soon after the affair, very tragicallybetween England and America……the Lusitania…I wish I had time to go and read yourletters…..that it opens up…but I simply cannot.…After the war is over I am intent upon going to England. And then making sure that we shall get together (period)
Jack and Charmian London
JL’s Dictaphone machinesfrom the JL State Park
1st of 12 cylinders from JL house with mold growth visible
1st Cylinder on 3D scanner Extracted audio waveform,(preliminary analysis) Voice of Charmian London 1915?
3D Scanning as a General Tool• A preservation tool for 3D scans of cylinders, discs, and dictation belts.
• With present technology this will not be fast but will provide the highest resolution digitizations available and extract the maximum information from the media
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Wax cylinder with mold Shellac disc Plastic dictation belt
Sample data scans on various media
