VisualAudio is a project that retrieves sound from a picture of a phonograph record. It originated from a partnership between the Swiss National Sound Archives and the School of Engineering and Architecture of Fribourg.
Discs were the only means of preserving sound before the introduction of magnetic tapes. [1] Until the advent of the vinyl in the 1950s, the records were made of shellac or wax. The organic composition of these materials enabled them to degrade over time and also made them prone to attack by fungi.
As a result, many records, including unique original radio productions, are in a state of deterioration which precludes play by traditional mechanical means, [2] hence the interest in a non-contact approach.
The idea of this recovery of the sound of old records through optical scanning started in the summer of 1999 in Lugano, among the technical manager of the Swiss National Sound Archives (Fonoteca Nazionale) Stefano S. Cavaglieri (creator and holder of the intellectual property, initiator of the project), the former director of M & C Management and Communications SA Pierre Hemmer (co-creator of the project), and the Director of the Swiss National Sound Archives Pio Pellizzari (co-creator of the project).
The Fribourg school of engineering and architecture (Hochschule für Technik und Architektur Freiburg) was the main partner, [2] at first studying its feasibility and then starting a project that progressed over years. [3]
During normal playback of a phonograph record, sound is obtained by a stylus following the groove. The radial displacement of the groove is observable through a microscope which means that sound information is visible. [3]
If a high-resolution analog picture of each side of the record is taken and the information in the film is then digitised using a circular scanner, various algorithms can process the image in order to extract and reconstruct the sound. [4]
A central part of the process is photo shooting. It is performed at the beginning of the process on a properly cleaned record, in order to archive it as a film.
The photographic film has a high resolution of 600 lines per mm. This resolution is sufficient to accurately follow the groove displacement.
Once the record content is stored on a photographic film, the next step is to recover the original sound. The University of Applied Sciences of Fribourg built a scanner prototype to do this.
The current[ when? ] version of the scanner is made of a glass rotating plate, [1] on which is placed the film. The digitisation of the image is done by a linear CCD camera of 2048 pixels wide, which takes pictures at regular intervals, with frequencies ranging from 25,000 to 200,000 lines per rotation. The combination of the camera with the rotating film delivers a rotary scan of the record in the form of a rectangular picture of a ring. A second radial movement provides the next ring. [3]
Once digitized, the images are processed to analyze and determine the positions and displacement of the groove. The first step is to correct the imperfections of the captured images. Many disturbances can come from various stages of the acquisition process: the record itself (cracks, scratches, dust), the photography (film grain), or the scanning (dust, optics, CCD sensors).
Then, the groove position is estimated using edge detection algorithms. Once the edges are detected, corrections requiring more complex knowledge about the structure of the image are carried out. Some examples of corrections:
The final step is converting groove displacement into an audible signal. This signal is processed by band-pass filters in order to obtain only the bandwidth of the original recording. Some frequency equalizations (for instance RIAA) are implemented. [3]
This project aims to retrieve and archive the sound as close as possible to the original one. By default, audio restoration is not applied.
The ultimate goal of this project is getting sound out of an otherwise forever lost record.
Many records from the 1940s are cracked and definitely unplayable. The result is an interesting jigsaw puzzle. As the cracks are due to the shrinkage of the lacquer, there is no material loss in most of the cases. To solve this problem, in November 2006, the Swiss National Sound Archives started a project funded by the Gebert Rüf Foundation. The results so far are encouraging. The algorithm basically uses signal features to determine whether two groove parts are contiguous or not.
The project is still[ when? ] in a test validation phase, but some sound is already available.
Reaching the same quality as good as an original record replayed on a modern turntable is probably unrealistic. Originally around 20 dB in the early prototype, [1] the signal-to-noise ratio of modern system is situated around 19 dB for a good 78 rpm record.
With its intermediate photographic stage, this solution solves several significant challenges found in archiving systems.
Disadvantages of the system:
Among the unique audio files recovered with such techniques, the speech of Italian politician and poet Aldo Spallicci. [5] [6]
A phonograph, in its later forms also called a gramophone or since the 1940s called a record player, or more recently a turntable, is a device for the mechanical and analogue recording and reproduction of sound. The sound vibration waveforms are recorded as corresponding physical deviations of a spiral groove engraved, etched, incised, or impressed into the surface of a rotating cylinder or disc, called a "record". To recreate the sound, the surface is similarly rotated while a playback stylus traces the groove and is therefore vibrated by it, very faintly reproducing the recorded sound. In early acoustic phonographs, the stylus vibrated a diaphragm which produced sound waves which were coupled to the open air through a flaring horn, or directly to the listener's ears through stethoscope-type earphones.
A record producer is a music recording project's overall supervisor whose responsibilities can involve a range of creative and technical leadership roles. Typically the job involves hands-on oversight of recording sessions: ensuring artists deliver acceptable performances, supervising the technical engineering of the recording, and coordinating the production team and process. The producer's involvement in a musical project can vary in depth and scope. Sometimes in popular genres the producer may create the recording's entire sound and structure. However, in classical music recording, for example, the producer serves as more of a liaison between the conductor and the engineering team. The role is often likened to that of a film director though there are important differences. It is distinct from the role of an executive producer, who is mostly involved in the recording project on an administrative level, and from the audio engineer who operates the recording technology.
Imaging is the representation or reproduction of an object's form; especially a visual representation.
Mastering, a form of audio post production, is the process of preparing and transferring recorded audio from a source containing the final mix to a data storage device, the source from which all copies will be produced. In recent years, digital masters have become usual, although analog masters—such as audio tapes—are still being used by the manufacturing industry, particularly by a few engineers who specialize in analog mastering.
A laser turntable is a phonograph that plays standard LP records using laser beams as the pickup instead of using a stylus as in conventional turntables. Although these turntables use laser pickups, the same as Compact Disc players, the signal remains in the analog realm and is never digitized.
The phonautograph is the earliest known device for recording sound. Previously, tracings had been obtained of the sound-producing vibratory motions of tuning forks and other objects by physical contact with them, but not of actual sound waves as they propagated through air or other mediums. Invented by Frenchman Édouard-Léon Scott de Martinville, it was patented on March 25, 1857. It transcribed sound waves as undulations or other deviations in a line traced on smoke-blackened paper or glass. Intended solely as a laboratory instrument for the study of acoustics, it could be used to visually study and measure the amplitude envelopes and waveforms of speech and other sounds, or to determine the frequency of a given musical pitch by comparison with a simultaneously recorded reference frequency.
Vitaphone is a sound film system used for feature films and nearly 1,000 short subjects made by Warner Bros. and its sister studio First National from 1926 to 1931. Vitaphone is the last major analog sound-on-disc system and the only one that was widely used and commercially successful. The soundtrack is not printed on the film, but issued separately on phonograph records. The discs, recorded at 33+1⁄3 rpm and typically 16 inches (41 cm) in diameter, are played on a turntable physically coupled to the projector motor while the film is projected. Its frequency response is 4300 Hz. Many early talkies, such as The Jazz Singer (1927), used the Vitaphone system. The name "Vitaphone" derived from the Latin and Greek words, respectively, for "living" and "sound".
The Capacitance Electronic Disc (CED) is an analog video disc playback system developed by Radio Corporation of America (RCA), in which video and audio could be played back on a TV set using a special stylus and high-density groove system similar to phonograph records.
A recording head is the physical interface between a recording apparatus and a moving recording medium. Recording heads are generally classified according to the physical principle that allows them to impress their data upon their medium. A recording head is often mechanically paired with a playback head, which, though proximal to, is often discrete from the record head.
Sound-on-film is a class of sound film processes where the sound accompanying a picture is recorded on photographic film, usually, but not always, the same strip of film carrying the picture. Sound-on-film processes can either record an analog sound track or digital sound track, and may record the signal either optically or magnetically. Earlier technologies were sound-on-disc, meaning the film's soundtrack would be on a separate phonograph record.
Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording.
Audio restoration is the process of removing imperfections from sound recordings. Audio restoration can be performed directly on the recording medium, or on a digital representation of the recording using a computer. Record restoration is a particular form of audio restoration that seeks to repair the sound of damaged gramophone records.
The history of sound recording - which has progressed in waves, driven by the invention and commercial introduction of new technologies — can be roughly divided into four main periods:
Record restoration, a particular kind of audio restoration, is the process of converting the analog signal stored on gramophone records into digital audio files that can then be edited with computer software and eventually stored on a hard-drive, recorded to digital tape, or burned to a CD or DVD. The process may be divided into several separate steps performed in the following order:
In sound recording and reproduction, audio mixing is the process of optimizing and combining multitrack recordings into a final mono, stereo or surround sound product. In the process of combining the separate tracks, their relative levels are adjusted and balanced and various processes such as equalization and compression are commonly applied to individual tracks, groups of tracks, and the overall mix. In stereo and surround sound mixing, the placement of the tracks within the stereo field are adjusted and balanced. Audio mixing techniques and approaches vary widely and have a significant influence on the final product.
A mixing engineer is responsible for combining ("mixing") different sonic elements of an auditory piece into a complete rendition, whether in music, film, or any other content of auditory nature. The finished piece, recorded or live, must achieve a good balance of properties, such as volume, pan positioning, and other effects, while resolving any arising frequency conflicts from various sound sources. These sound sources can comprise the different musical instruments or vocals in a band or orchestra, dialogue or foley in a film, and more.
The following timeline tables list the discoveries and inventions in the history of electrical and electronic engineering.
A disc cutting lathe is a device used to transfer an audio signal to the modulated spiral groove of a blank master disc for the production of phonograph records. Disc cutting lathes were also used to produce broadcast transcription discs and for direct-to-disc recording.
IRENE is a digital imaging technology designed to recover analog audio stored on fragile or deteriorating phonograph cylinders, records, and other grooved audio media. It is in use by several archives and preservation institutions in the United States seeking to preserve and digitize historical audio.
A click is a sonic artifact in sound and music production.
{{cite journal}}: Cite journal requires |journal= (help)