Practical Visualaudio

Federal Department of Home Affairs FDHA Swiss Federal Office of Culture FOC Swiss National Library NL

Practical VisualAudio

A long journey to tangible results. Practical aspects, challenges, ups and downs, room for improvements.

JTS 2016, Singapore, 7-9 March 2016 Federal Department of Home Affairs FDHA Swiss Federal Office of Culture FOC Swiss National Library NL

• Microscopic observation of the surface of a disc: • The shape of the groove visually represents the acoustic vibrations, which closely correspond to the electric signal, of the recorded sound. • There's plenty of information available, but it requires a very high resolution photography or scanning.

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• A schematic overview of the VisualAudio concept: • The disc is photographed (high resolution copy) • The film is scanned (image digitization) • The raw image is processed (groove reconstruction) • The final image is transduced to sound (sound extraction)

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• Why the analog photographic step? • The photo is an accurate, high-res copy. • It is a quick and reliable way to freeze the degradation of the surface of a disc. • A certain depth of field is granted by well known photographic principles. • Film is a small, cheap, stable medium.

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• Some additional benefits of analog photography: • The picture is shot without interfering with the surface of the disc. There is no need to manipulate the disc, except for placing it inside the photo camera. • Discs in virtually all conditions (even delaminated, broken, deformed, etc.) can be read and the sound restored. • Each and every disc format (size, speed, cutting, etc.) is read using the same equipment. • Image processing is very well established. It is relatively easy to make corrections to the physical incoherencies of the disc. • Film is a quite stable, small, and cheap carrier for storing sound information. We may consider it a long term storage format.

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• Main parts: the 1st generation photo camera

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• Main parts: the 1st generation photo camera… its current location

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• Main parts: the 1st generation photo camera… how we got it there

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• Main parts: the 3rd generation photo camera

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• Main parts: the 1st generation turntable scanner

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• Workflow and average timings: • Photography: 10' (disc positioning, picture shooting, film development) • Film scanning: 30' (film positioning, ring-by-ring scanning and merge) • Image processing and image-to-sound transduction: 2h 30' (groove alignment and reconstruction, image-to-sound transduction, de- emphasis) These processes are independent. They may be carried out by various people, in various locations, on a different schedule. The timing as for steps 2 and 3 is just a guidance, it relies very much on the shape of the disc.

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• Audio(visual) samples: • How does a ring look like? • Linking the grooves • Lonesome blues (Sindey Bechet's Blue Note Quartet); BLUE NOTE 13; RS 709-A (HR6052) (constant amplitude vs. constant velocity, linear vs. de-emphasized) • O lacrima (Ernst Krenek), part I (96kHz 24bit, 21kHz and 48kHz LPF) • AES 78rpm test record, side B (turntable vs. VisualAudio) • Noise floor • Harmonics

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• Room for improvement: • The current image sampling frequency is of 64 or 128ksamples/ring, while standard audio sampling frequencies are of 44.1, 48, or 96kHz. How do this different figures correlate? • On an image, the radial position of the groove can be estimated by detecting the edges of the groove (2 or 4). On a turntable it is determined mechanically by the pivot and the inertia of the arm, as well as the stylus tracking the groove. What is the impact on the audio quality? • Image processing extracts the position (i.e. the amplitude) of the groove, while a stylus gets the velocity. Is the derivative (i.e. the signal) the same for both methods? If so, can we apply the same de-emphasis, such as the RIAA or any other less known curves?

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• Room for improvement (cont.): • Is it possible to get a better digital image by using a (semi-)automated imaging tool for improving sharpness and contrast and reducing noise? • Or, thinking outside the box, what about developing a tracing system instead of scanning, i.e. something like a laser beam the follows the groove on the image? • Is any of the other optical retrieval systems, such as IRENE or ELP, suitable for processing our analog pictures?

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The concept of VisualAudio itself and all these questions lead to…

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• A broader view • The business of audio archiving can be summarized as: • To provide broad sonic access to our cultural heritage as it has been captured and preserved in sound. • To provide the faithful reproduction of the intended signal source – “Preserve history, not rewrite it”. • To collect and preserve recordings as a means to provide sonic access. • There is currently no existing global solution: • Investment in engineers, technologies, and research not proportional to the mission. • Millions of recordings with grossly insufficient staffing, inadequate tools. • Need for a strategic plan to assess and implement evolving technical advances to address mass transfer and global access.

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• A broader view (cont.) • Today’s self assessment, best practices model: • No enforceable mechanism for adherence. • No universal quality control or assurance. • Not supportive of a degree of education. • History of incorrect practices. • Possibly leading to forever corrupted files: • “Record everything” re-recordings co-mingle all signal and noise sources assuming that someone in the future will be better able to address issues. • But there’s neither evidence that co-mingled noises will ever be able to be separated, nor that anyone will ever have time to go back. • Pragmatism can lead to stagnation not innovation.

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• A broader view – G•MARC • The mission statement of the G•MARC initiative, meaning Global Media Archive Research Consortium, is:

To support research, develop applications, and design and produce standards-based systems and procedures specific to the needs of media archiving.

• How does VisualAudio fit into G•MARC? Imaging is an objective means for transferring the physical representation of a sound recording (i.e. the groove) to another media while retaining full authenticity.

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• A broader view – G•MARC • The mission statement of the G•MARC initiative, meaning Global Media Archive Research Consortium, is:

To support research, develop applications, and design and produce standards-based systems and procedures specific to the needs of media archiving.

Stay tuned!

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• In the meantime you may listen to some sound samples, watch some video demonstrations, get more information at http://www.fonoteca.ch/visualAudio/

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