From the 1930s to the end of the fifties, most audio recordings of radio stations were kept on 78rpm discs (magnetic tapes only started to be used routinely in France from 1950). Over time these records (discs) have deteriorated through handling or natural causes. Some records of priceless historical value can no longer be read by the usual means (magnetic cells with a diamond stylus) and the surface of the disk cannot be mechanically restored. Some 20,000 of INA's 276,000 discs are in such a condition. The same applies in a large number of archives of radio broadcasting organisations all over the world.
Scratched, broken or split discs cannot be played by mechanical means. This is also true of discs whose surface has altered and deteriorated.
Our process can read these discs optically, without a stylus and without any physical contact.
In 2002 INA devised an innovative process (patented in 2004) for optically reading audio discs based on reflective properties of the groove walls. With the participation of INDEEP, in the framework of the PrestoSpace project, we have carried out research and designed a device that converts the signal from pictures of the disc's surface into an audio signal.
Benefits compared with mechanical reading processes:
Benefits compared with other optical reading processes:
The retracted cellulose lacquer on these discs makes them unreadable with conventional processes.
A dedicated interface allow controlling disc decoding, here a broken glass-base lacquer disc.
 George Brock-Nannestad, "The Attraction of Optical Replay of Mechanical Recordings" (AES Conference, Oct. 2001)
 Louis Laborelli, Jean-Hugues Chenot, Alain Perrier, "Non contact Phonographic disks digitisation using structured colour illumination", proceedings of AES 122nd Convention - Vienna 5-8/5/2007
 Louis Laborelli, Jean-Hugues Chenot, Dust Detection by Colour Analysis in an Optical of Phonographic Disks Digitisation. Proceedings of ICIP 2007 (IEEE International Conference on Image Processing, San Antonio, 16-19/9/2007)
 French patent Louis Laborelli FR2874280, published 17/2/2006 : Équipement pour la lecture optique des disques phonographiques analogiques
 US, EU patent Louis Laborelli (US200604498, US7660208B2, EP1626402, DE602005002890T2) : Equipment for the optical playback of analog phonographic records.
 Ottar Johnsen, Frédéric Bapst, Lionel Seydoux, "Sound extraction of delackered records" proceedings of the AES conference 2008, San Francisco
 Vitaliy Fadeyev, Carl Haber, "Reconstruction of Mechanically Recorded Sound by Image Processing", Journal of the Audio Engineering Society (JAES), vol. 51, no. 12, pp.1172-1185 Dec. 2003
Roughly 20,000 of INA's 276,000 discs can no longer be played with conventional means. We are working on finalizing a version of the system that can decipher such discs. We then plan to find partners to offer industrialised systems to radio broadcaster's archives departments all over the world, or to digitizing service providers.
Current team :
For their participation, we thank :
Training engineers : Delphine Chadefaux, Maxime Bocquier, Aurélie Fosso, Rémi Peltier, Nicolas Grosset-Grange
We thank all colleagues from the archive department in INA for their support.
This work was supported by European Commission in the framework of PrestoSpace project (FP6-IST-507336 2004-2008), and by French Fonds national pour la Société Numérique (FSN), Cristal project (FSN-AAP1-012085-405850, 2011-2012).