Ripping Vinyl Via Your Scanner?

An anonymous reader writes "This site describes a method of extracting audio off of scanned images of vinyl records. Kazaa vinyl swapping is on it's way!" While this method creates exceptionally noisy samples, you can definitely hear the underlying music.

Comments

what's next?

[joejoejoejoe]

A device that can extract 1000 words from a picture?

The angles of stereo records are well known

[isdnip]

The original author failed to research how vinyl records work, something that "everybody" knew 20 years ago, before CDs.

Now to see if my memory still works. Mono LPs used horizontal modulation; the needle moved back and forth within the groove. Stereo can be viewed two ways. Vertical is difference (L-R), horizontal is sum of the L+R. Viewed differently, the two diagonal walls of the groove are the two channels.

A flatbed scanner can only see the horizontal, so it might work a bit with mono, but it won't work too well! However do note that some very, very expensive ($10k+?) new turntables actually do use optical "needles" to track the groove without touching it. Talk about low tracking force!

looks possible

[alizard]

These numbers are EXTREMELY approximate, I just wanted to see if his claims are possible. They are.

Standard rotational speed = 33 1/3 RPM

12" record

Circumference = pi * D

33.3RPM /60 ~ 0.5 R/second

12" * pi ~ 37" circumference.

0.5 * 37" = 18.5"

18.5 * 600dpi = 11,100 samples per inch, which gives a Nyquist limit of 5550Hz... a 2400 dpi or better might actually give full audio bandwidth, though in this case, the higher the better, since the area available for sampling decreases towards the center of the record, and for really high fidelity sound, more than 2 samples at 20K are necessary.

His model for how the record was encoded is *wrong*. The RIAA method of stereo modulation (back when they were mostly a standards organization) places the amplitude information on each wall of the V-shaped groove. It is intended to be picked up with a stylus connected to a something in the form of an Y , with channel information picked up by coil or magnet or other means attached to each upper leg of the Y.

Fixing his model should result in drastically improved performance if he's extracting stereo information. Cleaning the record would also help a lot.

His project actually *is* worth doing. An optimized algorithm should allow anyone or a museum with a good scanner to turn his vinyl (SPELLED CORRECTLY) collection into decent quality Red Book or MP3 tracks without any further damage to the records. The basic problem is to linearize the relationship between 16-24 bit gray scale information of reflected light and the depth modulation in each groove.

The suggestion of using software to extract 3D information from the grooves posted elsewhere is a good idea, but this is a good start.

Cool hack.

show me the code

[wadiwood]

Perhaps this guy could put the code on floppy disk, photocopy it and fax it in.

Or scan the floppy the same way as he scanned the LPs and email the jpg.

Re:Of course it's a hoax

[Draoi]

Like I just pointed out on another thread, the source has been posted here.

The guy goes on to say;

Woke up, fell out of bed... rampaged by a slashdot horde.

Some clarifications to the slashdot crowd:

I am sorry so many of you thought this page was a hoax only because no source code was supplied (I'm sure you'll all agree, now that you can see the code, that it is both straightforward and crappy).