Even when some recorded carriers seem to be lost forever, it is sometimes still possible to act! That’s why a unique project for the preservation of lacquer discs was jointly launched in early 2021 by INA (French National Audiovisual Institute), meemoo (Flemish Institute for Archives), VRT (Belgian Flemish Radio and Television) and Gecko. Today, 51 of the 52 sides have been saved from the test of time.
Entitled SIRDUKE (Saphir Innovatively Rescues VRT Discs Using Knowledge and Equipment), this project follows the VRT disc digitization campaign that took place in Brussels between 2017 and 2020, for which Gecko made its technical resources and its recognized know-how of more than 15 years available for the digitization of severely damaged lacquer discs. The VRT still had other lacquer discs whose critical condition left little hope of being played back, without technology up to the challenge.
What is Saphir?
Saphir is a lacquer disc playback system developed since 2004 by Jean-Hugues Chenot and Jean-Étienne Noiré at INA. Composed of a hardware part (the scanner) and a software part, it allows to playback without contact the most fragile analog audio discs. After the development of numerous prototypes and improvements, the system has now reached sufficient maturity to go beyond the test phases and to consider daily production in complex projects.
The principle of Saphir is based on the fact that the groove’s sides of a laterally engraved disc behave like a mirror. The process uses a projection of a light beam onto a small area of the disc surface. As a result, the sides of the groove appear colored in the image. The color returned depends on the orientation of the groove side, and will therefore vary according to the audio signal.
The digitization of a disc takes place in three phases:
A glass protection disc is placed on the lacquer disc. The plate rotates slowly during the capture and the color variations of the reflected beam in the groove are photographed by a fixed camera.
The software will generate a multitude of audio fragments from these photos. The numerous parameters to be set during this step will allow the software to follow the groove correctly and to obtain the best signal/noise ratio, and the least distortion possible.
The audio fragments are placed in the right order and the software suggests a complete groove path on the entire side of the disc. The operator controls the parameters of the software and gives indications on the path to be followed with the help of graphic constraints.
Why use an optical playback process?
Optical reading offers real advantages when discs are in a very degraded state. Only Saphir optical reading system can extract information from the most difficult discs, despite the use of advanced traditional reading techniques implemented at Gecko.
The project’s success
This can be considered the first time the Saphir has been tested under real-world conditions with a relatively large number of discs from a third-party background. Gecko’s experience and expertise provided positive feedback to Jean-Hugues Chenot, thanks to the work of Adrien Bailly, Gecko sound engineer.
Gecko finally succeeded in processing almost all disc sides, with varying results depending on the state of the discs. However, traditional playback is still preferred in most cases, both for reasons of cost and audio quality. For the most difficult cases, such as the SIRDUKE project, Saphir is a solution that has saved records that would have been lost forever.
“The SIRDUKE project has been a success thanks to INA Saphir, a project that Gecko has been following since its creation. As specialists in the digitization of lacquer discs, and now that Saphir is mature, it has proven to be the missing link in our production chain. We thank meemoo, VRT and INA for making this project possible, and especially Jean-Hugues Chenot for his invaluable help.”
– Jean-Baptiste MEUNIER, Gecko CEO