[HN Gopher] Digital Needle: Ripping vinyl records with a scanner
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Digital Needle: Ripping vinyl records with a scanner
Author : marcodiego
Score : 130 points
Date : 2021-04-26 17:58 UTC (5 hours ago)
(HTM) web link (www.cs.huji.ac.il)
(TXT) w3m dump (www.cs.huji.ac.il)
| tmountain wrote:
| I remember seeing something online a very log time ago where
| someone was using Perl to encode audio into image files (jpeg
| IIRC) and then subsequently decoding them (losing fidelity in the
| process). Even though I understand the science that makes this
| work, it still feels like magic. Love it.
| Dylovell wrote:
| The next thing will be electron microscope scans of of the
| instruments the artists used. I'm joking. I really want well
| digitized vinyl
| kurthr wrote:
| You're joking, but based on the dynamic range (claimed by
| audiophiles) over a min length of ~160um (more on the outside
| less interior for 2kHz tone) and the peak motion ~37um per
| channel.
|
| PVC grains are typically 100s of um in size, but the monomers
| themselves are ~10nm. Note that with 120dB claimed dynamic
| range this would be 37nm of deflection (at 45deg or 25nm
| lateral) for full resolution. That is close (3x off) to
| molecular Atomic Force Microscopy.
|
| Of course what is encoded is actually force/velocity which in
| turn is inductively coupled out, but it is no surprise that
| simple optical scanning gives you mediocre results. Even 10x
| lower dynamic range requires 250nm optical resolution. It's
| doable, but not easy.
| tantalor wrote:
| The "decodings" are awful.
| dylan604 wrote:
| I can't tell the difference between the inability of this
| process to capture the audio and the distortion one normally
| hears introduced by MP3 compression. </s>
| marcodiego wrote:
| Thinking about a simpler system... how about getting a camera on
| a turntable recording a video while the record turns. It would
| then be possible to track a line with an specified width in the
| video and turn the changes in a piece of this line it into a
| waveform.
| verelo wrote:
| This would be a cool project
| porterde wrote:
| Also capture the audio sample from the same record alongside
| the video. Repeat with lots of records. Train a model to
| predict the audio from the video. Voila! Play records with just
| the camera "stylus"...
| 3dee wrote:
| I once thought about building this, but it's much harder than
| you think.
|
| The data has to be processed very quickly. I believe you should
| think in terms of 0.3m groove per second.
|
| If you put a camera above the groove you also need something
| like a stepper motor to control the arm.
|
| But I believe the biggest problem is dust. A needle will move
| small particles out of the way, but a camera does not.
|
| This is also why laser turntables need 'clipping' filters. Dust
| will create all kinds of noise you don't want to hear.
| Scene_Cast2 wrote:
| I remember wondering whether a laser "needle" could work. IIRC
| the format has some funky EQ and other things to make a physical
| needle work better.
| philjohn wrote:
| The funky EQ is the RIAA curve[1] - by essentially rolling off
| the bass and boosting the treble you can fit more on a disc, it
| attenuates some of the clicks and pops and is kinder on the
| vinyl and needle.
|
| It's trivial to invert in software, and as another response
| points out, there is indeed a working laser record player -
| although the record needs to be extensively cleaned before
| playback or it doesn't work very well.
|
| [1] https://en.wikipedia.org/wiki/RIAA_equalization
| dehrmann wrote:
| This is part of what people hear when they say "vinyl sounds
| better."
| andrewzah wrote:
| That doesn't make any sense. RIAA EQ is a serialization
| format, that is then decoded by your audio equipment.
| That's what the phono jack is for on a receiver, pre-amp,
| etc.
|
| What people "hear" regarding LPs is generally their biases
| + their particular analog setup. My setup is going to sound
| totally different than yours, regardless if it's from a CD
| or an LP.
|
| There are some cases where an LP had a better -master- than
| a CD for the same release, but that is due to the
| publisher/owner of the master tracks and not the actual
| medium itself.
| Yaa101 wrote:
| I found out when digitizing vinyl that LP's before 1977,
| when digital mixing and mastering was not the norm that
| there is more data in the frequencies between 20 and
| 50kHz. I do my recording standard at 192kHz and analogue
| LP's often reach 48kHz of data while digital mastered
| ones do only 22kHz. After that date often the frequency
| is cutoff at 20-22kHz, probably to save memory room. Only
| after 2000-2010 there is enough memory to record at
| insane sample rates and bits per sample. Most awful are
| cds having only 16 bits and 41kHz sample rate, by modern
| standards really poor.
| andrewzah wrote:
| "Most awful are cds having only 16 bits and 41kHz sample
| rate, by modern standards really poor."
|
| 44.1kHz is all that one needs for -perfect fidelity-,
| given that humans cannot hear higher than ~20kHz. See:
| Nyquist-Shannon Sampling Theorem. [0] 16 bits of
| quantization gives a Signal to Noise Ratio (SNR) of 96dB,
| and noise dithering increases that [1]. More bits are not
| necessary unless one is doing music production with that
| audio and warrants the extra headroom, before mixing back
| to 44.1kHz/16bit for distribution. [1]
|
| The only thing that higher bits/sampling rates do for a
| listener is waste CD and drive space, so it is odd to
| lament 44.1kHz/16bit as being "really poor". Even if your
| speaker setup can actually output extremely high
| frequencies, only your dog will be able to hear it...
|
| [0]: https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shanno
| n_sampli...
|
| [1] https://web.archive.org/web/20181109203430/https://pe
| ople.xi...
| h2odragon wrote:
| Some humans can hear much higher than 20khz. Very little
| of our recording and playback equipment does well above
| that point, however, so efforts to reproduce that part of
| the spectrum most often fail miserably.
|
| CD's are certainly good enough for now.
| pezezin wrote:
| The only source I could find about humans hearing above
| 20 kHz is this paper reporting that some people could
| detect tones up to 28 kHz:
| https://asa.scitation.org/doi/10.1121/1.2761883
|
| But that is for a pure tone under perfect laboratory
| conditions. Also, they report that the minimum hearing
| threshold at those frequencies was above 90 dB. So I
| don't think any human in this planet can actually hear
| anything above 20 kHz under normal circumstances, much
| less for music.
| Yaa101 wrote:
| I am doing production with these recordings, tools are
| more precise at higher bit and sample rates. Also quality
| of listening equipment is a factor as hearing is not a
| flat frequency response, things as ambiance and resonance
| play a role, music is not a single frequency tone but a
| combination of complicated frequency additions,
| subtractions, multiplications and divisions. So more
| frequency room can produce nicer highs and clearer sound,
| especially when music is uncompressed. It is simplistic
| to state that 44.1/16bit is enough, if that is the case
| then any combination of recording, amplifier and speaker
| would suffice. This just isn't the case, also that we
| would need awesome priced equipment isn't really worth
| it. But there really is a difference between a phone with
| a music app playing a 16bit/44.1kHz song on a medium
| quality headphones and a dedicated player with a good DAC
| chip playing a 96kHz song on a good quality headphones.
| People that cannot hear the difference should not invest
| in such equipment and will be happy with the need to
| invest less money for their entertainment.
| carlmr wrote:
| >It is simplistic to state that 44.1/16bit is enough, if
| that is the case then any combination of recording,
| amplifier and speaker would suffice.
|
| No, that doesn't follow. It just means that recording at
| those bit rates and sampling frequencies isn't the
| "bottleneck" for the sound in the system.
|
| >But there really is a difference between a phone with a
| music app playing a 16bit/44.1kHz song on a medium
| quality headphones and a dedicated player with a good DAC
| chip playing a 96kHz song on a good quality headphones.
|
| When everything you compare to is better quality then of
| course it sounds better. But it's not due to the 96kHz vs
| 44.1kHz. Nyquist-Shannon is mathematical reality.
|
| You have to compare the same high quality headphones, the
| amp with the same DAC, with the same recording, being
| played through a high quality filter bringing everything
| down to 44.1kHz/16bit.
| summm wrote:
| 44.1/16 is enough for distribution. This is not
| simplistic. It simply can reproduce waveforms up to the
| nyquist frequency perfectly within a defined noise range.
| That's a mathematically proven fact. Of course you can
| botch that with bad listening equipment, but there's
| nothing a ridiculously oversampled signal would improve
| given the same listening equipment. You do speak about
| the studio processing right?
| bluGill wrote:
| There are one of several things.
|
| Most likely, CDs just don't get mastered right. The music
| is compressed and so even though the format is better, the
| music is worse. Vinyl is sold to people who care about
| sound, in their living rooms so they get better mastering.
| Digital is for people out and about, in your car you need
| compression even though it destroyes the music you can't
| even hear 3/4ths of the sound without it. This isn't the
| fault of the format, but the result remains, digital music
| is objectively worse.
|
| Vinyl is able to get a slightly better S/N ratio in perfect
| conditions. So if the record is new it might be better
| (every time you play the record you wear it just a bit).
| Odds are it isn't, as almost nothing has enough dynamic
| range for this to matter.
|
| They are used to worse sound and prefer it. CDs are perfect
| - vinyl often introduces imperfections that people like to
| hear. By objective measurements the music isn't perfect,
| but they like that imperfection.
|
| Most likely it is the first. It is by far the most
| significant difference.
| andrewzah wrote:
| "Vinyl is able to get a slightly better S/N ratio in
| perfect conditions."
|
| No. Compact Discs have an SNR of 96dB. Vinyl typically
| has an SNR of 60-70dB. The physics of these mediums
| aside, CDs are a newer technology... Why would we have
| gone for inferior distribution mediums?
|
| "Most likely, CDs just don't get mastered right. The
| music is compressed and so even though the format is
| better, the music is worse"
|
| Compression like that has more to do with radio play +
| the genre of music. Thankfully, the loudness wars are
| mostly over, but generally speaking the actual
| distributed master would've been the same.
|
| "This isn't the fault of the format, but the result
| remains, digital music is objectively worse."
|
| Please provide such objective citations. Mixing and
| mastering engineers do their best to make music that
| sounds good on a variety of audio systems. When I worked
| in a studio, we would mix on $8k genelec monitors, some
| cheaper monitors, and also test the mix in our cars and
| on our phones. Part of the art and difficulties in that
| was producing a mix that sounded good on great to average
| systems, and passable/decent on like mono phone speakers.
| Music and music hardware has never been more accessible
| than today, so I find it hard to believe that everyone a
| few decades ago had such amazing systems compared to
| today.
|
| "Vinyl is sold to people who care about sound"
|
| Citation needed. There are people who just want vinyl
| because it looks cool (especially the colored limited
| releases), and they go play it on a $50 Victrola all-in-
| one. There are CD enthusiasts who have systems worth >
| $200k.
|
| "CDs are perfect - vinyl often introduces imperfections
| that people like to hear."
|
| This is totally subjective. A CD is a bit-for-bit perfect
| representation of what the author wanted to distribute.
| The actual things like "warmth" that people talk about
| depend much more on the pre-amplifier, amplifier, and
| speakers.
|
| There is nothing wrong with liking LPs (I collect them
| myself), but they are in no way, shape, or form better
| than the bit-for-bit perfect distribution of CDs (that
| also don't degrade every time you play one).
| genewitch wrote:
| >"When I worked in a studio, we would mix on $8k genelec
| monitors, some cheaper monitors, and also test the mix in
| our cars and on our phones."
|
| Yes! When i was producing an album a year, i'd write in
| monitor headphones, master on bookshelf monitors + a
| smallish subwoofer, then computer speakers, my car
| stereo, and a friend's street comp A car stereo. It's the
| only way to be sure that my ears in the "studio" weren't
| being biased by the overall quality of the sound damping
| and accoustics of the room.
|
| And objectively, i know that CDs are "pure". I also
| really can't hear the difference between a mastered 96khz
| 24 bit raw audio file, FLAC, or ~300ABR Mp3. And before
| it's mentioned, i have much better hearing than anyone i
| know, even if i have lost the ability to distinguish
| words when someone talks to me off-axis. the other night
| i heard my nearest neighbor playing music, and no one
| else could, here. Neighbor is like 1/4 mile away, from
| inside their house to inside my house. I brought my
| tascam to the back door and recorded[0]. Sure enough, the
| recording has a high noise floor but you can see the bass
| hits.
|
| I still prefer live electronica shows where the DJ has
| pennies taped to their stylus, but i watch DJs on twitch
| using laptops and DJ-I digital turntables. All this to
| say, i've never made fun of someone spending thousands on
| pre-amps, amps, speakers, decks, whatever. If someone
| likes the way a Marantz sounds, or a Pioneer, or JBL or
| klipsch speakers - it doesn't affect me at all.
|
| We're not using skippy CD players and realaudio/56kbit
| mp3s anymore!
| shagie wrote:
| > Why would we have gone for inferior distribution
| mediums?
|
| Higher data density, easier to manufacture, portable.
|
| While we often phrase it as "vinyl vs CD" it was more a
| "tape vs CD". And CD is arguably the better technology
| there.
|
| In https://www.soundguys.com/vinyl-better-than-
| streaming-20654/ - there is a chart of "Music sales by
| media" and you will see that CD - it replaced cassette
| tapes. Another view of similar data - https://blogs.sas.c
| om/content/graphicallyspeaking/2019/11/11...
|
| And even with that, "the best technology wins" isn't
| always the case. One could make a reasonable argument
| laser disks were better than video tapes and that Beta
| was better than VHS.
|
| There are forces beyond the pure technology comparison at
| work in market dominance.
| marcodiego wrote:
| Already exists: https://en.wikipedia.org/wiki/Laser_turntable
| voldacar wrote:
| not cheap, but yeah it works great.
|
| https://www.elpj.com/
|
| I actually got to hear one once. Extremely neutral and high-
| res, but the record has to be super clean because with the
| laser, you _will_ hear every little speck of dust. Also it
| doesn 't work with colored vinyl, iirc.
|
| edit: they use 5 different lasers to get the data out of the
| groove, go read the section on their site, it's actually really
| intricate and cool
|
| > the format has some funky EQ and other things to make a
| physical needle work better
|
| Yes, in order to fit the high bandwidth music signal into a
| groove with a fixed width, the bass is EQed down and treble
| EQed up, since for a _constant velocity_ sine wave, a low
| frequency wave would take up more physical width on the record
| than a high frequency wave. Without this EQ, you would only be
| able to store a small amount of music on a record. When the
| record is played, your phono preamp applies an inverted EQ
| curve to restore the signal to its original frequency response.
|
| In the past, there were lots of different vinyl equalization
| curves, but the RIAA curve has been standard for decades now.
|
| https://en.wikipedia.org/wiki/RIAA_equalization
| TylerE wrote:
| Noise is also a big part of the RIAA curve.
|
| Almost all the noise on a record is high frequency...so by
| applying a strong treble rolloff most of it just disappears.
| voldacar wrote:
| Yes that's also very important - the inverted EQ applied by
| the phono preamp pushes the noise floor way down in the
| treble, while raising it in the bass. In my opinion, this
| is probably why vinyl can never compete with digital when
| it comes to clean-sounding bass, but can generally have
| equally detailed treble when cared for well and played on a
| good turntable
| dylan604 wrote:
| Sounds like DolbyNR for cassettes. What high hats?
| TylerE wrote:
| It's a lot more clever than that.
|
| Because the music has the exact inverse transform applied
| it before it's cut to the master, you don't lose any
| signal, just noise.
| aidenn0 wrote:
| Dolby NR was intended to be that way as well, but turning
| Dolby (type C) NR on removes tape-hiss from non-dolby
| tapes while also as GP said fading certain frequencies.
| m463 wrote:
| I wonder if they could do what film scanners do - they use an
| IR channel.
|
| EDIT: and as soon as I submitted I realize film scanners scan
| for light and maybe use the IR channel for physical scanning.
| with a record everything is physical.
|
| or maybe the IR channel focuses on a different plane? could
| they use different wavelengths for distance
| sensing/separation?
| Syzygies wrote:
| Slide/negative scanners use multiple passes and depth
| perception to cleanly ignore dust on film. I'm surprised that
| this wasn't part of ELP's spec to the engineers. A giant fail
| if they can't even remove this noise in post-processing.
| voldacar wrote:
| There's no AD step in the ELP. it's an analog system from
| the laser to the line out. So there's no way to do multiple
| passes while listening to the record, though you can adjust
| the depth in the groove that the laser scans.
| 11thEarlOfMar wrote:
| "The record has to be super clean..."
|
| Audiophiles likely know of this, but I'm still surprised.
|
| Clean vinyl records with glue...
|
| https://everyrecordtellsastory.com/2015/05/25/how-to-deep-
| cl...
| DavidVoid wrote:
| Cleaning with glue seems like much more of a hassle than
| using something like a SpinClean.
|
| If you want to thoroughly clean a vinyl record though, then
| an ultrasonic cleaner is the way to go (it is expensive
| though).
| dogma1138 wrote:
| Cleaning with glue isn't that difficult, buy the arts and
| crafts acrylic white glue mix it with water and spray it
| on the record (30% water / 70% glue works for me).
|
| Silly putty can also work in a pinch but some of them
| leave an oily residue.
|
| Spin clean works but the cheap machines can easily break
| the record and the expensive ones are expensive as fuck
| and can still result in damage due to user error.
| LeoPanthera wrote:
| > it works great.
|
| It does not work great.
|
| The problem is dirt, which sounds like a minor issue, but it
| renders the concept almost completely useless.
|
| A stylus pushes dirt out of the groove as the record turns. A
| laser cannot do so, and it's _virtually impossible_ to fully
| clean a record.
|
| The only remaining advantage is that a laser turntable does
| not wear out the disc, and it's an incredibly minor
| advantage, compared to simply playing a record once on a
| traditional player, and recording the output.
| marcodiego wrote:
| Other related projects:
| http://recherche.ina.fr/eng/Details-projets/saphir
| https://irene.lbl.gov/
| megaserg wrote:
| I've made a simple encoder/decoder some time ago:
| https://github.com/megaserg/schallplatten
| elevation wrote:
| Don't forget https://www.windytan.com/2017/07/gramophone-audio-
| from-photo...
| marcodiego wrote:
| And this one too: https://mediapreservation.wordpress.com/201
| 2/06/20/extractin...
| aidenn0 wrote:
| I wonder; could one project a horizontal line on a disc, a camera
| at an offset angle, and use the apparent deviations from a
| straight line for digitizing a record? I know there are full-
| analog laser players, but a full-digital solution might let you
| do fancy tricks to remove dust, particularly if you used multiple
| wavelengths of light, as slide scanners do.
| Koshkin wrote:
| Now I'm dreaming about a program that would simply play a high-
| res photograph (scan) of a vinyl disk...
|
| This also reminds me of the idea to use paper for archival. This
| is based on two factors: that modern office paper is extremely
| durable (and is likely to outlast most of the other physical
| media out there), and that scanners are (and have been for years
| now) extremely high-resolution; so, you can simply print the bits
| (say, of a zip file) as dots, and then you could use a scanner to
| read the file back!
| jccalhoun wrote:
| https://slate.com/human-interest/2013/04/patrick-feaster-dis...
| m463 wrote:
| you would still need to use a de-linted discwasher with de-
| ionized water:
|
| https://archive.org/details/stereo-review-presents-stereo-bu...
| thanatos519 wrote:
| This is art!
| the_local_host wrote:
| For some reason this reminds me of the Feynman article on HN
| recently ( https://news.ycombinator.com/item?id=26931359 ) -
| the enjoyment in pursuing something just because you think it
| would be fun.
| quijoteuniv wrote:
| This post somehow made me think that Carl Sagan golden record was
| not just a stupid idea. https://voyager.jpl.nasa.gov/golden-
| record/whats-on-the-reco...
| geocrasher wrote:
| These are _so wonderfully distorted_. I am getting somewhere
| between the signal in the movie "Contact" and whispers of the
| hive mind of the Borg. Amazing sounds, even if they aren't true
| to the recording.
| dmje wrote:
| Yeh. Thinking they'd make a pretty rad segment in an ambient
| track
| blackearl wrote:
| You might like The Caretaker. It's less about the music itself
| and more about how your mind and memories slowly deteriorate
| with age
|
| https://en.wikipedia.org/wiki/The_Caretaker_(musician)
| elevaet wrote:
| Hauntology!
| S_A_P wrote:
| Aside from the slight wah wah effect they are pretty great. I
| immediately loaded them up in my S2400 and resampled them to
| 12bit 26khz to add much aliasing Sample C2 is especially
| haunting this way.
| [deleted]
| Hfjfjdjfjceijfj wrote:
| Stero channels aren't encoded in the depth and radial axes.
| They're encoded in the same plane, but rotated 45 degrees, so a
| mono record player (depth only) plays a balanced sum of each
| channel.
|
| Edit: mono is radial only, not depth.
| MrsPeaches wrote:
| For anyone else who was intrigued by this, I found this helpful
| animation:
|
| https://www.vinylrecorder.com/stereo.html
| noman-land wrote:
| Amazing. Thank you. I immediately saved this, bookmarked it,
| and shared it with half a dozen people.
| WrtCdEvrydy wrote:
| Well, that definitely hurt my brain.
| dr_zoidberg wrote:
| When I read the title I immediately thought of a "laser tip"
| that and reading the reflections of it, not something based
| on software that would "read" an an image.
|
| Following this animation I'm left thinking that you could do
| a bit of filtering to better extract the wave(s) from an
| image, though you'd require a particular setup for the
| lighting conditions to get the best possible quality out of
| it. And then back to my first idea: probably a laser-tip
| would be the best tool here too.
|
| Unfortunately I don't have vinyl records around to test any
| of this!
| ilikejam wrote:
| Sure: https://en.wikipedia.org/wiki/Laser_turntable
| radomir_cernoch wrote:
| Wow, the best example of teaching minimalism I know. Even
| though the website fails on so many levels, ;-) I still get
| the message in 15 seconds.
| Fnoord wrote:
| This website, as well as the one in the thread's URL, are
| exactly in the way as I learned the WWW was when I first
| started using it.
| dehrmann wrote:
| I always found this solution to be an incredibly clever and
| elegant way to encode stereo sound while maintaining backward
| compatibility.
| fortran77 wrote:
| Yes, but it's actually equivalent to "Left - Right" being
| encoded in the vertical plane and "Left + Right" encoded in the
| horizontal plane.
| DavidVoid wrote:
| > so a mono record player (depth only)
|
| You mean horizontal only?
|
| Old Edison disc records encoded single-channel audio in the
| vertical axis (varying the depth), but regular 78s and single-
| channel vinyl records encode the audio in the horizontal axis.
| doggodaddo78 wrote:
| Random Q: do I have a damaged/bent stylus if a certain record
| (Toots and the Maytals' Pressure Drop picture disc) goes silent
| at several different times? I checked the stylus force scale at
| the different test points, and it's right in the middle of the
| cartridge specs.
|
| Every other record plays fine, except some new records play slow
| and/or some carve out a thin hair of lacquer/enamel the first
| time. This always makes me think some sort of damage is happening
| from a misaligned cartridge. But, other good quality and used
| records don't do this and work fine.
|
| It's an AT microline cartridge.
| ndeast wrote:
| If it is just happening with a specific record (especially a
| picture disc) it's likely not your stylus and just the
| pressing. You can give cleaning your record and stylus a shot
| and see if that helps.
|
| If records are playing slow make sure if your table is belt
| driven your belts are still in good condition. Also make sure
| your tonearm height and anti-skate are properly adjusted.
|
| Cleaning your records before you play them (even brand new
| records) is important.
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(page generated 2021-04-26 23:00 UTC)