Brad Ideas - Converting vinyl to digital, watch the tone arm - Comments

A "very high" resolution

brad — Wed, 24 Oct 2007 11:40:00 -0700

This would be a new level of very high resolution, I think. Distilled to CD-quality, a disk has 220MB of data, but as I said, that's distilled from the middle of the groves. An image has lots of extra information.

There is a fellow who tried this: http://www.cs.huji.ac.il/~springer/

And this:
http://www.s3.kth.se/kurser/2E1366/students/03/lightblue/index.html

(You can google for more hits on this, people have done a bunch of work.)

Near the end of the record, we see about 7 inches per second. I figure your image would need immense resolution because the height of the groove isn't something that will translate that well to light intensity, but perhaps something could be done. If you needed just 200,000 samples/second, that's 28,000 dpi, beyond the range of any scanner we have around. You could get 44,000 samples/second from a 6400dpi scan going perpendicular to the grooves. For this scan you would scan inward very slowly, as you would want 64,000 samples for each edge of the groove -- that's incredibly dense. (How "high" is the waveform on the side of the groove?)

If you could make it so a single sensor could measure the width of the groove based on light intensity, you could do amazing things, but so far the experiments in that area with lasers work to some degree but pick up dirt too much.

Picture

Chris — Wed, 24 Oct 2007 01:16:40 -0700

I would think an image of the disc at a very high resolution and an algorithm to translate the dics image is a .wav file. Like the laser/needle, but just a complete image and process it into a sound file in one readthrough.

All one big disk

brad — Tue, 23 Oct 2007 11:43:37 -0700

There's a nasty tradeoff between having it all look like a single disk and letting the user see the disk structure. Disks fail, or go into pre-fail state, and you want to be able to pull them and replace them. You also want to be able to move them sometimes. In addition, you don't want runaway applications that fill up the disk to stop other critical apps from working, like getting E-mail.

For a giant archive, one big volume may be fine.

There is, of course, another way to do the vinyl job, the way mp3.com did it before they were sued out of existence for doing it. Namely you prove you have the vinyl and you get MP3s or Flacs back. It's not legal, but the studios could do it themselves, and there was even a program for a while where you could bring in your old disks to record stores and get replacements for a discount.

The latter method solves the problem the RIAA worries about of people borrowing a friend's disk and thus getting free music, in that the store takes the vinyl or marks on the label with a pen. But it only would work for stuff that has been digitized already, and only for studios that would participate. And right now they would rather sell you your music again at full price (to fewer people) than let you have it at a discount.

No argument about the

Moz — Tue, 23 Oct 2007 01:55:38 -0700

No argument about the desirability and technical possibilities of ripping vinyl that way, and if I had the time I'd possibly be interested just as a geek project. But I suspect it wouldn't be quite as simple as we'd hope (having perfect pitch means disliking cheap CD players just on general principles).

Speaking of cool ideas, when is someone going to release a chainable NAS box? This hassle of spanning my stuff across multiple drives is annoying, it's like DOS all over again. Every time I fill up the array I have to split stuff to free space on the full unit and move it to the new unit. Why can't I just plug them together and say "ok, you are one drive now, all 8 or 12 or 20... hard disks worth of you". Well, for less than $50k, anyway. It can't be that hard, especially since half of them are running linux and software RAID anyway... ideally getting a RAID6 6+2 array out of it, but 2 RAID5 with JBOD NAS boxes would be acceptable. It might even be possible to homebrew using eSATA NAS boxes and motherboard JBOD... fragile though.

True

brad — Sun, 21 Oct 2007 11:38:34 -0700

Which does limit how much money can be put into products like this. I just like to figure out how you could make it good if you were building it.

Though indeed, a lot of it is not on CD. I taped about 30 of my albums onto VHS-HI-FI in the 80s. VHS HI-FI is actually pretty good quality (much better than cassette but not reel to reel) but the problem is getting a different VHS unit to track properly and not gum up the audio.

Also interesting is the ability to, with the combo of wow and flutter elimination, click and pop removal, a high sample rate and FLAC compression to make a recording that sounds better than what you can get from a turntable, if you had an audiophile cartridge and A2D. There are those who disdain CD with 44K 16 bit samples and certainly disdain lossy compressed music, but they should not disdain 96K sampled 24bit or floating point sampling with lossless or much less lossy compression. With disk space costing 25 cents/gigabyte today, the economics that governed the choices of CD are no longer present.

The technique I describe for removing wow and flutter could even be done without resampling, if you could have the clock on the A2D adjust in real time based on signals coming from the optical stripes on the platter. It might be able to make an audiophile digital copy with inexpensive equipment. Though of course, you never make cheap audiophile equipment!

With my VHS to DVD transfers, there was a lot to be said for the “one touch” mode of the box (which really was far more than one touch.) Though I did decide, in the case of various old movies and TV shows I had on VHS, that I would just buy such things using amazon or peerflix if I really wanted to see them again, because the quality would be so much better as well. So I actually restricted my transfers to personal stuff, stuff you can’t get on DVD, and stuff I only cared modestly about. There was a temptation which I should have given into to use the overnight one-button xfer to DVD+RW as a means to simply find out what was on a VHS more conveniently. I had a ton of old VHS tapes, 6 or 8 hours long, full of random shows, unmarked. For some of these I may do this technique. Since doing 6-8 hours means going to 352x240 resolution, it would mean if I actually really wanted something I would have to seek to it and re-do it. I suppose that might be a clever mode for the recorder — you seek to a spot on the DVD and say, “I want this piece of the VHS for 30 minutes” even without index marks, and it could do it.

Give up now, just buy them again

Moz — Sun, 21 Oct 2007 03:02:12 -0700

Having fscked about with this for quite a while, and seen how much hassle it is for audiophiles who care a lot more than I do, I suggest giving up while you're ahead. My approach when I finally got down to a small number of LPs that couldn't be found either in shops or online was to pay one of said audiophiles to rip the last 10 or so for me. Much cheaper overall than the time and hassle involved in ripping them all myself (I suspect the record companies are counting on this... and hoping we don't just download the illegally instead).

Actually, the best bit was tracking down and emailing a couple of the artists and in one case getting a CD directly with everything he had from the band he used to be in. Years later the album was released with 15 tracks instead of the 24 that I have :) The other group decided to put out a "when we were young" CD after all, since it's pretty cheap these days even with remastering costs. Both times I was happy to pay the artists for the CD.

Of great benefit there has been the recent Flying Nun retrospective collections and a couple of other compilation projects, because now I even have music videos from the olden days (New Zealand music from the 80s). Hopefully the more luddite record labels will eventually realise that this is a cheap source of profit too (remaster to CD, sell double CDs for $20... it's like printing money).

Converting vinyl to digital, watch the tone arm

brad — Sun, 21 Oct 2007 00:01:47 -0700

After going through the VHS to digital process, which I lamented earlier I started wondering about the state of digitizing old vinyl albums and tapes is.

There are a few turntable/cd-writer combinations out there, but like most people today, I’m interested in the convenience of compressed digital audio which means I don’t want to burn to CDs at all, and nor would I want to burn to 70 minute CDs I have to change all the time just so I can compress later. But all this means I am probably not looking for audiophile quality, or I wouldn’t be making MP3s at all. (I might be making FLACs or sampling at a high rate, I suppose.)

What I would want is convenience and low price. Because if I have to spend $500 I probably would be better off buying my favourite 500 tracks at online music stores, which is much more convenient. (And of course, there is the argument over whether I should have to re-buy music I already own, but that’s another story. Some in the RIAA don’t even think I should be able to digitize my vinyl.)

For around $100 you can also get a “USB turntable.” I don’t have one yet, but the low end ones are very simple — a basic turntable with a USB sound chip in it. They just have you record into Audacity. Nothing very fancy. But I feel this is missing something.

Just as the VHS/DVD combo is able to make use of information like knowing the tape speed and length, detecting index marks and blank tape, so should our album recorder. It should have a simple sensor on the tone arm to see as it moves over the album (for example a disk on the axis of the arm with rings of very fine lines and an optical sensor.) It should be able to tell us when the album starts, when it ends, and also detect those 2-second long periods between tracks when the tone arm is suddenly moving inward much faster than it normally is. Because that’s a far better way to break the album into tracks than silence detection. (Of course, you can also use CDDB/Freedb to get track lengths, but they are never perfect so the use of this, net data and silence detection should get you perfect track splits.) It would also detect skips and repeats this way.