James L. Wolf wrote: > Just wondering. Once the processing and storage capabilities for 3-D > modeling of a groove arrive (10+ years?), wouldn't it also be possible Personally, I think we are there already. Disk space is not an issue, so we can collect and process huge amounts of information, a prequisite for doing full 3-D topography of a record to the resolution needed. And as I noted, it would surprise me if there isn't already a surface topography measuring system or device (probably using lasers and suitable for our needs) being used right now in the research establishment for some purpose. It's amazing what technologies are routinely being used at the National Labs (and many industrial labs), many of which have not been commercialized. Even if the specific device hasn't yet been developed, there are probably people (the trick is finding who) at the National Labs or at universities, who could put something together rather quickly. I don't see this as being a big issue, having worked in the National Labs for almost 15 years. To me, the biggest issue is writing the code, with the requisite computer algorithms, to analyze the 3-D topography and therefrom pull out the recording -- to "virtually" play the recording and derive the best possible signal from the topography of the grooves. This will NOT be trivial. The one nice thing is once a 3-D topography is stored and archived (probably on MO disks), then as the digital "play-back" algorithms continue to improve over time, we can revisit earlier topography data without need to re-scan the rare original record. In addition, the precision of 3-D lithography continues to improve (which is used to make intricate physical objects from digital 3-D data), and it may be possible to "produce" a new physical record using the 3-D topographic data if mechanical (by stylus) playback is needed. Thus, this suggests the first stage is to develop the 3-D topographic measuring technique, and then apply it now to extremely rare/valuable recordings (even ones which are completely broken -- the full record can be digitally stitched together.) Then, the next step will be to begin developing the computer algorithms to digitally "play-back" the 3-D topographic data and restore the recordings. I foresee the digital playback algorithms to be in a continual state of improvement and refinement over time (and also for the 3-D topographic mapping, but I think refinement of that will come quickly, mostly in being able to do it faster.) > From what I recall of the lecture at the Library by two guys from > Berkeley who are working on something similar to the folks on the web > page cited, creating a 3-D map of a groove doesn't require anything > physical to be placed in the groove (if that's what you mean by a > probe), just two linked "cameras" to plot the coordinates of each point > of the groove. But it takes a hell of a long time. I think with current > hardware and technology it takes a couple days to 3-D map a 2-minute > cylinder, maybe more. Oh, definitely. Using any mechanical system to ride in the grooves is totally unnecessary. We only need to make a 3-D digital "snapshot" of the recording's surface. The key is to be able to do it to high enough resolution with minimal error. There is the issue of speed, but I think over time the system can be perfected to run quite fast. As an aside, there is work now being done on 3-D memory/data storage, which requires two or three laser beams to focus on a point within a 3-D matrix of some sort to determine if it is a '0' or a '1'. They are talking about sugar-cube sized chucks of this material holding 50 gigabytes to a terabyte of information, and that the transfer rate can be as high as 1 gigabyte/second. I think a laser scanning system for precision 3-D topographic mapping of records can eventually be designed to run at very high speed, where mapping the entire surface of a 10" 78 rpm disc could be done in just a few minutes, if not just a few seconds. > But 3-D is the only way to go. Jon Noring is absolutely right; 2-D > is a waste of time. It only reads the edge(s) of the bottom of the > grove, the results I've heard (under relatively good listening > conditions) were really poor, and vertical grooves are impossible, so > there's no point in messing with it, except maybe for emergency > preservation of broken laquers or something similar. Putting it another way, when one drags a stylus (or even a laser beam) through a groove, one ends up linearizing all it picks up. It is a *huge* loss of information. I think that by avoiding this high entropy-producing linearization, we will be able to filter out a lot of the noise and distortion of older recordings *before* they are digitized. Once you mix the noise with the signal, as what happens with linearization (linear playback by stylus or laser), it is nigh impossible to reverse this process (truly separate the noise from the wanted signal.) It would not surprise me that for some records, using the 3-D topographical mapping approach, and developing advanced "playback algorithms", we will see miraculous restoration (much better signal-noise ratio and much less distortion) now impossible to achieve by the current state-of-the-art transfer and digital restoration methods which rely on dragging a stylus (or a laser beam) through a groove and then trying to untangle the huge mess it produces. This is not to say that further digital sound processing restoration of the signal will not be necessary, but that what is fed to the final stage of digital sound restoration (declicking/ decrackling/noise reduction/etc.) will be of much higher quality, maybe approaching vinyl test pressing quality even from shellac sources in say E- or E condition. Jon Noring