Slashdot Mirror
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.
A device that can extract 1000 words from a picture?
Silly Rabbit: tricks are for kids.
Serious audiophiles would simply buy a laser turntable to minimize the wear and tear. Although it probably sounds more like a cd than anything.
http://www.elpj.com/
Only the State obtains its revenue by coercion. - Murray Rothbard
Get out the lawyers big bad music companies. There is hell to pay, for this new copyright violating technology.
I can't wait to start ripping my parent's vinyl. I used to listen to it all the time as a kid, and now my Pentium II is finally advanced enough to play 100 year old technology.
Saskboy's blog is good. 9 out of 10 dentists agree.
I take it back. I don't think it's a cool hack, I think it's a cool hoax. WHBT.
Pretty funny write-up, actually, but I'll believe he actually did it when I see the code.
-- Alastair
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!
No no: Kenny G albums would be vile .
If you scan it backward, are there satanic messages?
Comment removed based on user account deletion
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.
Tech Public Policy stuff
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.
-- it must be true, it's on the internet.
http://arts.ucsc.edu/ems/music/tech_background/TE- 19/teces_19.html contains basic information on how the LP record works. I think the most important thing for the experimenter is called RIAA equalization, in order to limit the physical motion of the recording stylus that cut the record, bass was reduced and treble increased in a very precise way, in order to reproduce the original sound, the opposite must be done.
The RIAA equalization curve is a plot of amplitude boost/cut vs. frequency. Apply its inverse to the raw analog signal(s) that come out of your signal processing.
You can find it at http://www.tanker.se/lidstrom/riaa.htm.
Oh, and CLEAN THE RECORD BEFORE DOING THIS. The info in Part 14 of the rec.audio.* FAQ is as good a place to start to find out how as any.
Have fun and feel free to let me know if you get anywhere.
You might also want a look at my other post to this thread.
Tech Public Policy stuff
The guy goes on to say;
Alison
"It is a miracle that curiosity survives formal education." - Albert Einstein