We propose an innovative contactless optical playing device for 78rpm and 33rpm lateral modulation phonographic disks, using structured colour illumination. An area of the disk is illuminated by a beam of rays, with colour depending on the direction of incidence, that are reflected by the groove wall towards a camera image. In contrast with standard methods, that measure the velocity of the groove at a single location, direct access to the audio signal value is obtained here directly from pictures through colour decoding, and the whole height of the groove wall is exploited. This colour coding allows for the detection of occluding dust, and automated interpolation of missing audio signal. Results on distortion, S/N ratio, and bandwidth are presented.

Authors: Chenot, Jean-Hugues; Laborelli, Louis; Perrier, Alain
Affiliation: INA (Institut National de l'Audiovisuel)
AES Convention: 122 (May 2007) Paper Number: 7009
Publication Date: May 1, 2007
Subject: Audio Archiving, Storage, Restoration, and Content Management

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