Ideas from the table: virtual vinyl

There are ideas that live for a long time. One of these ideas is digitizing a record by scanning its surface. Scanning is different, but simplified to 2D and 3D. Mostly on the Internet, a lot has been said and written about experiments on 2D scanning of records.

Consider the option of volumetric scanning.

The essence of the idea: 3D scanning of a plate -> Processing and saving a 3D image -> Creating a virtual player with a virtual 3D needle -> then stranded wires to a Hi-Fi technology.

Waiting for the reader under the cut.

A series of articles that once wanted to do, but did not. In the hope that someone can come in handy or just enjoy your time reading.

A bit of history and subject area. The first thing that comes to mind when phrases are digitizing records is an ensemble of technical devices in a vinyl player and then everything depends on the taste and knowledge of the designer, the list of equipment for converting an analog signal and the digital code is wide (the option of converting an analog-to-analog signal such as magnetic the tape we skip). Simplified the digitization process can be illustrated with the following photo:

The above process of converting an analog signal into digital form is widely illuminated from all possible sides and overgrown during its existence with myths and legends, especially regarding deeply subjective parameters, such as for example: “live”, “tube”, “soft” sound.

An article for example: How to digitize vinyl records.

Even just a single record player can generate heated debate, such as the weight of the player’s base capable of extinguishing microvibrations, the material and shape of the pickup needle, pickup suspension systems, plate stabilizers, power sources, wire thickness and material, and methods for their manufacture. I remember a documentary about a small western company specializing in the production of exclusively beds for expensive players weighing under 50kg. A small article about the top players.

An example of a photo weighing under 175 kg.

A small slide about the player's pickup device:

read more in Wikipedia articles: gramophone record and sound pickup .

All this tells us that the theme of reproducing "live" sound is relevant against the background of the renaissance of analog sound, including vinyl records. It is pleasant to recall the feeling of the record being taken out of the case, inspecting it at certain angles for detecting micro-scratches, because a scratch could of course turn into a problem of playing a piece of music and then the process of reproduction.

Let us touch on the simplest scanning option, 2D scanning the surface of a plate to take a snapshot of the tracks and then playing it back on a computer using a specially written program that converts the image of the tracks into a sound signal.

A short article on Habré on this topic: Extracting sound from photographs of records

Here, the option of scanning and playback in real time is possible, when a small area of ​​the plate is scanned and the scanner moves over the rotating plate like a pickup needle repeating the path of the sound track, but without direct contact with the plate. On this principle, there are mass-produced players .

Photograph of the laser player, where the scanning element is a laser beam, and reproduction occurs by measuring the reflected beam from the surfaces of the plate track.

The topic of self-creation of such a device is well covered in the next conference, the dialogue has been going on there for over eight years: Laser player for vinyl records.

There are much fewer materials on the 3D scan of records on the Internet. There is an interesting publication about an experiment on translating a sound signal into a 3D image of a plate, further printing it on a 3D printer and playing the sound on a regular turntable player. The article is called Printing LPs on a 3D printer.

There are publications about the process of restoring sound from museum exhibits, in this article " Sound Reproduction R & D Home Page " just describes the process of working with both 2D and 3D scanning. Moreover, old wax rollers and other sound carriers, often destroyed or broken apart, are scanned. On the history of sound carriers before the onset of tape cassettes, the next slide:

We are already half a step away from the idea of ​​the article, so let's do it.

Today, the volume of ordinary photos is measured in megabytes, phones have gigabytes of memory, clouds with free terabytes and other successes of microelectronics manufacturers. Digital memory has ceased to be a bottleneck of many technologies. It turns out that at the present time the end user is not particularly limited by the amount of required memory, therefore, with the permission of the reader, I will omit from the article the calculations of the memory volumes required for digitizing the record.

Briefly about the essence of a possible experiment or business (as it is more convenient for someone to imagine):

The first stage: Stereo-scanning of the surface of the record, followed by the restoration of the height map with a step that is obviously redundant in terms of preserving the signal recorded on the record. Scanning methods may vary: the most accessible is stereo photographing under a microscope, not in the sense that it is simple, but solely due to the inaccessibility of scanning electron microscopes and other electron-vacuum devices, it is possible to use mono-micro-scanning from different angles of the plate sections and further software Restoration of the surface shape. Since this is not a guide to action, but more to inaction, then the reader's fantasies are full of scope here. As an option, optical scanners of a computer mouse may be suitable for the role of a scanning element, but I will not say for sure without knowing the optical resolution-magnification of the surface of these devices.

Second stage: Processing of the received stereo image in 3D format, the technology has already been developed. Noises and other scanning artifacts are eliminated. Also at this stage it is possible to eliminate dust microparticles on the surface of the plate by software. Previously, this required special knowledge: Useful tricks for the care, storage and cleaning of vinyl records . We assume that at the output we obtain a polygonal model of the plate surface, based on the scan data.
While we have a 3D model with the size and number of polygons obtained from raw data, there is also room for optimizing the shape and number of polygons, it is possible to apply splines for a more accurate approximation of the sound track surface or other mathematical methods.

The third stage. Mathematical modeling of the movement of the needle of the player on the material of the record, taking into account data on the scanned surface of the sound track. The degree of study of mathematical modeling can be any, up to the complete disregard of physical processes such as friction and heating of the pickup needle, internal deformations and stresses in the needle material and the area of ​​contact of the needle with the surface of the plate, etc. The author's intuition suggests that even a “simple” repetition of the relief of a scanned record can lead to a quite decent sound quality in terms of quality Hi-Fi.

If the author has already uttered the coveted Hi-F, then of course I’ll clarify and absolutely agree with the thesis that at the end of sound modeling there is a digital-to-analog converter (DAC), and it will spoil everything in terms of “live tube” sound. But after all, it is possible to print a plate on the printer from the future with the necessary accuracy, and now it is probably possible to make a cutter on vinyl blanks in order to enjoy a rare copy of the plate sent by a pen-friend, for example from another continent, as a 3D image. Or listen through the computer DAC. I understand that there are codecs designed to compress lossless audio data ( FLAC ), but we also get something similar, but closer to the direct copying is not the sound, but its carrier.

What next, the reader will ask. I would like to draw a rainbow picture of digital 3D copies of records that are walking across the world. Internet platforms for the exchange of disk images, maybe even using cryptocurrency. But in reality, I hope I have refreshed the reader’s memories of the time when they went to the store for records, as if for books, which is now not so often the case. And for those who did not find this time, just the time to start modeling 3D records, in the future matrix, they will completely become a hot commodity. Thanks for taking the time to read.