[HN Gopher] The LaserDisc
       ___________________________________________________________________
        
       The LaserDisc
        
       Author : rbanffy
       Score  : 95 points
       Date   : 2024-05-01 12:19 UTC (10 hours ago)
        
 (HTM) web link (www.abortretry.fail)
 (TXT) w3m dump (www.abortretry.fail)
        
       | Maximus9000 wrote:
       | The photos aren't great at showing the scale. It was like a CD
       | but it was as big as a vinyl record. like this:
       | 
       | https://farm4.staticflickr.com/3833/9373539522_a3065346b8.jp...
        
         | PopAlongKid wrote:
         | >On the convenience front, the discs were a foot across, about
         | half a pound, easily damaged, and had to be flipped half way
         | through a film.
         | 
         | there is one picture near the end of the article ("Domesday")
         | that does show the scale relative to a standard
         | keyboard/monitor.
        
           | detourdog wrote:
           | I have never felt older than ready these comments. I started
           | working with interactive media exhibits right in between
           | laserdiscs and mpeg files.
           | 
           | I loved the tension between the quality of analog devices and
           | the convenience of digital.
        
             | RetroTechie wrote:
             | Same. When I was born, optical storage did not exist in
             | _any_ form. It was vinyl, cassette tapes  & floppy disks.
             | Lasers were SoTA things that scientists worked with. Not in
             | consumers' hands.
             | 
             | Then (besides LD & VHS) came the CD, which has gone a bit
             | out of fashion lately.
             | 
             | Then the DVD. Which was popular in its heyday, but also
             | over the hill.
             | 
             | Then Blu-Ray. Not to mention a truckload of recordable &
             | rewrite formats, DVD-RAM, MO discs & what have you. On the
             | computer side, flash & TB hdd's for cheap.
             | 
             | Disclaimer: and I'm not even _that_ old yet! Neither
             | retired or owner of a gray beard.
        
           | js2 wrote:
           | Behold, the epsilon turn:
           | 
           | https://youtu.be/t34dj8m1UGw?si=qh0JB48bmcpxY26B
           | 
           | The player stops spinning the disc, rotates the laser around
           | to the other side, then starts spinning the disc in the
           | opposite direction.
        
           | jonhohle wrote:
           | Later high end players had lasers on both sides and would
           | "auto-flip" for you.
        
         | userbinator wrote:
         | Also double-sided. AFAIK there weren't any single-sided LDs,
         | which meant the unused side had to be filled with something
         | else, like this memorable graphic:
         | https://www.youtube.com/watch?v=QwTDdyZTX48
        
           | itisit wrote:
           | The dead side of _A Video Standard_ [0] was white opaque
           | plastic. Still a physical side, but not a readable one
           | obviously. Closest I've seen to a single-sided disc.
           | 
           | [0] https://www.lddb.com/laserdisc/10498/LD-101/Video-
           | Standard-A...
        
           | crtasm wrote:
           | I wonder why they didn't stamp the same data on both sides?
        
         | toast0 wrote:
         | > It was like a CD but it was as big as a vinyl record
         | 
         | Vinyl records are just black laserdiscs that are audio only :P
         | Well, some records are jell-o colored, but you know.
        
       | acuozzo wrote:
       | FWIW, over the past ten years I've pieced together the largest
       | collection of MCA DiscoVision LDs in the world.
       | 
       | My goal all along has been to digitally preserve it for all.
       | 
       | I have a background which lies at the intersection of embedded
       | programming, broadcast engineering, and video restoration, so I
       | definitely have the technical chops to do so, but what I lack is
       | time since I have three young children at home.
       | 
       | It's somewhat stressful having what would otherwise be a neat
       | retirement project hanging over your head in your 30s, but I feel
       | fortunate enough to possess so many rare pieces.
       | 
       | I just wish I had someone passionate about it to share it with in
       | order to give me drive when my drive is low.
        
         | itisit wrote:
         | As a lifelong laserdisc aficionado, I would love to lend a hand
         | here if you're in the tristate area!
        
           | bluejekyll wrote:
           | I found it funny to see "tristate area" since I used to hear
           | it growing up so much.
           | 
           | For reference though, the term actually doesn't refer to
           | anywhere specific, there are many tristate areas,
           | https://en.m.wikipedia.org/wiki/Tri-state_area
        
             | itisit wrote:
             | I should have said " _the_ tri-state area. " :)
        
               | CalRobert wrote:
               | Solid, liquid, gas?
        
               | dylan604 wrote:
               | It is video related, so plasma could be valid as well
        
               | JTyQZSnP3cQGa8B wrote:
               | As a European, I'm confused and would love to know more
               | about _this specific_ area.
        
               | bluejekyll wrote:
               | As an American, I'm equally confused. I will say that
               | based on my experience, the tristate areas I often see
               | referred to are around New York and Philadelphia.
               | 
               | New York: New York, New Jersey, Connecticut.
               | 
               | Philadelphia: Pennsylvania, New Jersey, Delaware.
        
               | svieira wrote:
               | And if you're from a little-further-south it is
               | (naturally) Washington DC's version of the same thing
               | (Maryland, Virginia, West Virginia)
        
               | tmm wrote:
               | I guess that's true if you're west of DC. Otherwise it's
               | Delmarva (DELaware, MARyland, VirginiA).
        
               | bluGill wrote:
               | Tristate is used in things like radio where you are
               | covering 3 states. "Here is the news/weather in the
               | tristate area". They mean specifically the 3 states that
               | the radio signal reaches, which is clear to everyone.
               | Since they reach 3 states there is no other name that can
               | be used for their coverage area. The people in question
               | regularly cross state lines.
               | 
               | It isn't a useful concept to bring up when you are not
               | physically in a tri-state area.
        
               | epcoa wrote:
               | Chicago: Illinois, Indiana, Wisconsin
        
               | itisit wrote:
               | Much like residents of _the bay area_ [0], I 'm playfully
               | suggesting there's only one tri-state area of
               | significance [1].
               | 
               | [0] https://en.wikipedia.org/wiki/San_Francisco_Bay_Area
               | 
               | [1]
               | https://en.wikipedia.org/wiki/New_York_metropolitan_area
        
               | toast0 wrote:
               | California has _three_ regions known as the  'South Bay'.
               | 
               | https://en.wikipedia.org/wiki/South_Bay_(Los_Angeles_Coun
               | ty)
               | 
               | https://en.wikipedia.org/wiki/South_Bay_(San_Francisco_Ba
               | y_A...
               | 
               | https://en.wikipedia.org/wiki/South_Bay_(San_Diego_County
               | )
        
               | vel0city wrote:
               | Arkansas, Texas, Louisiana?
               | 
               | Oh, you must be talking about the tri-state area with the
               | Tri-State Airport: Kentucy, Ohio, West Virginia.
               | 
               | https://en.m.wikipedia.org/wiki/Tri-State_Airport
        
               | gosub100 wrote:
               | Everyone being pedantic would change their tune instantly
               | if it were an even money family-feud style bet for the
               | top answer.
        
           | acuozzo wrote:
           | I'm in Maryland, but I grew up in NY/NJ, so I almost
           | accidentally replied saying that I am, haha.
        
             | itisit wrote:
             | Bummer! Fun project to have.
        
           | buildsjets wrote:
           | Oregon-Washington-California?
        
         | bluedino wrote:
         | I remember them being comically large and making fun of the
         | loading process. Meanwhile we are just throwing VHS tapes
         | across the room to someone else and they plop them into the
         | player.
        
           | metadat wrote:
           | Yes, but LD was nearly twice the resolution:
           | 
           |  _> LaserDisc had several advantages over VHS. It featured a
           | far sharper picture with a horizontal resolution of 425
           | television lines (TVL) for NTSC and 440 TVL for PAL discs,
           | while VHS featured only 240 TVL with NTSC._
           | 
           | Even still, there is no arguing that Laser Discs looked
           | comically large and are an awkward dimension compared to VHS
           | tapes.
           | 
           | https://encrypted-
           | tbn0.gstatic.com/images?q=tbn:ANd9GcQs29ra...
        
             | stavros wrote:
             | That's four times the resolution, no?
        
               | metadat wrote:
               | I meant twice the vertical resolution :) you're correct.
        
               | babypuncher wrote:
               | Analog video resolution is only measured vertically, as
               | lines.
               | 
               | Measuring horizontal resolution gets fuzzy (literally),
               | though it's not hard to believe that the LaserDisc's
               | extra bandwidth gave it more horizontal resolving power
               | than VHS.
        
         | JTyQZSnP3cQGa8B wrote:
         | I can't help you for this, but it feels good to have
         | passionate/crazy people out there doing what they like. My only
         | advice would be to take care of your family first, take your
         | time, and have fun. Never be in a stressful situation because
         | it's not worth it, you're supposed to live your life after all.
        
         | metadat wrote:
         | I hope you create a mega torrent of it all!
         | 
         | Have you considered contacting the Internet Archive? They might
         | be keen to assist you in your efforts or in at least stably
         | hosting the blobs.
         | 
         | https://archive.org/about/contact.php
         | 
         | In fact, they already have quite the LD compendium:
         | 
         | https://archive.org/details/laserdiscs
        
         | LocalH wrote:
         | ld-decode is such a fascinating piece of software
        
           | metadat wrote:
           | To save folks the search query:
           | 
           | ld-decode - https://github.com/happycube/ld-decode
           | 
           | Also worth mentioning the fork, vhs-decode -
           | https://github.com/oyvindln/vhs-decode which was discussed
           | here previously.
           | 
           |  _VHS-Decode - Software defined VHS decoder_ -
           | https://news.ycombinator.com/item?id=33942490 - September,
           | 2022 (81 comments)
           | 
           | Edit: Thank you @LocalH for the link typo correction.
        
             | LocalH wrote:
             | you left an e off the first link, friend, hope you catch
             | this before you can't edit :)
        
               | jonhohle wrote:
               | You _do_ keep it copacetic!
        
         | detourdog wrote:
         | I want to do the same sort of thing. I thinking a high quality
         | the laserdisc version of the black & white videos may be as
         | good as it gets.
         | 
         | I have a pretty good mpeg encoding workflow from that era. My
         | ultimate plan is to create a local media archive for an 8 unit
         | apartment building.
         | 
         | I think streaming is pretty inefficient without gaining any
         | real selection advantage.
        
         | jonhohle wrote:
         | I'm sure you're aware of the Domesday Duplicator[0] and related
         | projects.
         | 
         | There's several MegaLD/LDROM2 discs that need preservation that
         | I hope I can help with one day.
         | 
         | 0 -
         | https://github.com/simoninns/DomesdayDuplicator/wiki/Overvie...
        
           | sumtechguy wrote:
           | The use of multiple copies to remove dropouts has been
           | interesting there too. Think MAME just added some of the
           | games in a couple of months ago that have been thru this
           | process. So even if they have a copy your copy could be of
           | use.
        
             | pkroll wrote:
             | Not just dropout: the disc stacker will set each pixel to
             | the median (if there are enough copies) or an average (if
             | there are just two) so even slightly off pixels on one disc
             | of three, will be caught/fixed. (You can do the same thing
             | with VHS, but not with their stacker software. You'll need
             | to resort to VapourSynth or Avisynth/Avisynth+.)
        
         | dylan604 wrote:
         | how would one get in touch with you regarding this? i worked on
         | a site that never took off archiving DJ mix tapes as I had
         | several professional cassette players. the main reason it
         | didn't take off was from DJs not following through with sending
         | me the cassettes. also, nobody wanted to fund the site, and
         | nobody wanted to deal with potential copyright crap.
         | 
         | we have similar, but different, backgrounds. i was in
         | film/video post house at the transition from film to digital,
         | from analog tapes to digital tapes, built a couple of machine
         | rooms for different companies, made a career for knowing the
         | film-to-video stuff that's no longer taught nor properly
         | understood. being able to code is the kicker
        
           | acuozzo wrote:
           | Awesome!
           | 
           | I'm pretty flexible. Do you have a communication platform you
           | prefer?
        
             | dylan604 wrote:
             | my username here at the googly email service works for me
        
               | acuozzo wrote:
               | E-mail sent!
        
         | iancmceachern wrote:
         | You are awesome!
         | 
         | I already bought my brother his Christmas gift (shhh, don't
         | tell him). It's a Braveheart laserdisc signed by Mel Gibson.
         | 
         | I never had one, but some of my fondest memories from childhood
         | is me at the video store wondering if I would ever have a
         | laserdisc player. Someday.
        
         | reaperman wrote:
         | passthepopcorn.me has an 'archive team' with a lot of redundant
         | storage available and they also have 'encoding teams' with
         | quite a few passionate, motivated people each with decades of
         | experience in video restoration. They've got the free time that
         | you lack and generally would be quite happy to learn new
         | techniques from you and take critical feedback into account.
        
         | behringer wrote:
         | There's dozens of us. Check out the laserdisc forever group on
         | Facebook.
        
           | acuozzo wrote:
           | I'm there. My username here is just [first letter of given
           | name] + [surname] and my surname is pretty unique, so if you
           | search for it there you'll find posts I've made in the past.
        
       | ghaff wrote:
       | I have a Pioneer LaserDisc player and 200-300 discs in my garage.
       | Hate to throw them out but also no interest in dealing with
       | shipping. I live about an hour west of Boston. If interested
       | email me at the address in my profile _after June 1_. Address in
       | profile. No charge but ask you to make contribution to an open
       | source project of your choosing.
       | 
       | Hopefully not inappropriate but seemed a good forum to rehome.
        
         | stronglikedan wrote:
         | I put my player and collection out for bulk pickup and labeled
         | it as to what it was and that it worked. It was picked up by
         | some random stranger before I got back from walking the dogs. I
         | really hope they enjoyed it.
        
           | ghaff wrote:
           | I've had good luck with furniture and non-functional lawn
           | equipment. I'm in a semi-rural location but at the end of a
           | long driveway off a fairly busy road.
        
         | detourdog wrote:
         | I would email you but I don't see your address. I'm in western
         | mass and have some interest.
        
           | ghaff wrote:
           | Ah. You have to put in your about box. To keep it fair wait
           | for June as I'm out of the country and don't want to shut off
           | inquiries for a month because someone said they were
           | interested.
        
       | busseio wrote:
       | The scene in SLC Punk where Mark (Til Schweiger) is giving a tour
       | of his home, the LaserDisc part is one of my favorites.
        
       | asveikau wrote:
       | Last year I found a laserdisc player on the sidewalk in San
       | Francisco in 100% working condition. I took it in and got a few
       | discs at local record stores.
       | 
       | It was the second time I saw a discarded laserdisc player on a
       | San Francisco sidewalk. I can't recall when the other time was,
       | maybe 2019ish.
       | 
       | Edit: If anyone reading this is in the Bay Area looking for a big
       | laserdisc haul, the owner of the Video Room in Oakland is
       | retiring and has a large inventory that you would need to contact
       | him privately for. I spoke to him once. He said he opened the
       | store in the early 80s as a LaserDisc rental place, and he has
       | thousands of discs in his garage.
        
       | duxup wrote:
       | I remember as a kid seeing a neighbor showing off his LaserDisc
       | and at the time thinking "This is really cool, but we just got
       | rid of records.... surely this can be done better and soon."
       | 
       | Soon wasn't very soon, but it was certainly one of those very
       | capable, very cool, and yet tangibly not exactly what it could be
       | type of technologies.
       | 
       | It's interesting how sometimes there's tech that absolutely is
       | very cool and yet seems to just not quite be there just yet.
        
       | voxadam wrote:
       | Technology Connections has a decent five video series on the
       | history of LaserDisc. It's some of his earlier work so the
       | production quality isn't quite where his newer videos are today
       | but it's still worth a watch.
       | 
       | https://www.youtube.com/playlist?list=PLv0jwu7G_DFUoByWSHHoS...
       | 
       | He also has a newer series on the far more obsucre CED
       | (Capacitance Electronic Disc) from RCA that's really interesting.
       | 
       | https://www.youtube.com/playlist?list=PLv0jwu7G_DFVP0SGNlBiB...
       | 
       | https://en.wikipedia.org/wiki/Capacitance_Electronic_Disc
        
         | ljf wrote:
         | Back in about 2008 I found a huge load of UK CED discs for
         | sale, plus about 10 different players. As someone who'd been
         | fascinated by vcd, I was interested in this other appendix
         | media - sadly I didn't buy it all, but for the best, looked
         | like a massive lot!
        
           | ljf wrote:
           | Actually man would have been 2004 - it was this site that I
           | lost days to - https://www.cedmagic.com/selectavision.html
        
         | Tokkemon wrote:
         | I love Alec's work on the CED. So good and really nicely
         | narrative-driven, which is kinda rare in this "let's review old
         | technology" genre.
        
       | AdmiralAsshat wrote:
       | The article glosses over LaserDisc's use in arcades and
       | videogames. It probably would've been worth mentioning its use in
       | the popular arcade game, Dragon's Lair:
       | 
       | https://en.wikipedia.org/wiki/Dragon%27s_Lair_(1983_video_ga...
        
         | FuriouslyAdrift wrote:
         | I think half my paper route money went to that game... that and
         | Gauntlet (Wizard needs food badly).
        
           | dylan604 wrote:
           | Gauntlet was the first simultaneous multi-player game I
           | remember. The first time playing it with 3 other friends was
           | "one of those things" growing up that I'll never forget.
           | Something different about it with all four people crowding
           | around the same screen vs playing with many more people
           | isolated at home across a network
        
         | CharlesW wrote:
         | https://en.wikipedia.org/wiki/Category:LaserDisc_video_games
        
         | rikthevik wrote:
         | I still feel burned about how I put a hard-earned loonie into a
         | Dragon's Lair machine and immediately died. At least at Street
         | Fighter I got a few rounds in.
         | 
         | Dragon's Lair was beautifully animated, innovative, and
         | absolutely not for me. I'm not sure if it's a game, to be
         | honest. :) It's fun to look back at old tech, seeing the ideas
         | that didn't quite land.
        
       | metadat wrote:
       | Interesting vocabulary alert:
       | 
       | indefatigable; _adj._
       | 
       |  _incapable of being fatigued : UNTIRING_
       | 
       | --
       | 
       | What a fun word, though I had to check the pronunciation
       | (available via a button @ https://www.merriam-
       | webster.com/dictionary/indefatigable).
       | 
       | p.s. David Paul Gregg was a real hacker, what an impressive
       | story. I like how he stuck to his guns and accepted termination
       | rather than give up the patent to his employers, first Westrex
       | and then again at 3M/Mincom.
        
       | grose wrote:
       | There's a small, CD sized version of the LaserDisc called CD
       | Video (also a related format called Video Single Disc). I've
       | always wondered whether it would be possible to use CD-Rs to make
       | one. Could CD burners somehow be coaxed to write the analog data
       | for the video? It can only fit 5 minutes of video but I think
       | vaporwave artists would love it, and it could keep the format
       | 'alive' with the first new content in decades.
       | 
       | https://en.wikipedia.org/wiki/CD_Video
       | https://en.wikipedia.org/wiki/Video_Single_Disc
        
         | bonton89 wrote:
         | Way back in the early 2000s before DVD burners were cheap my
         | buddy downloaded what appeared to be a handicam rip of the
         | Fellowship Of The Ring off limewire (or kazaa or whatever was
         | popular at the time) and burned it on 7-8 or 8 CD-Rs which we
         | could watch on his DVD player in the living room. The quality
         | was poor but watchable, but I think this had more to do with
         | the clandestine source than the medium. He had above average
         | computer literacy but probably just used a common program in a
         | way I've never used before to do this. DVD burners became
         | cheaper later and I never saw or thought much about this stunt
         | again.
        
           | rbanffy wrote:
           | Video CDs employ MPEG encoding. Resolution is 320x240, IIRC,
           | and bandwidth is the same as an audio CD.
        
           | Symbiote wrote:
           | That would be a Video CD, which has MPEG data lille a DVD,
           | but lower capacity.
           | 
           | https://en.wikipedia.org/wiki/Video_CD
        
       | shagie wrote:
       | My family had a laser disk... while we had some of the standards
       | (Star Wars) there was one that we had that took the media to an
       | interesting place. I want to say it was "Kids Disk" but I could
       | be wrong.
       | 
       | It had _many_ chapters that you could jump to with different
       | things. Some of them were things like  "learn to dance the Irish
       | Jig". That chapter had music in one channel and instructions in
       | another - so you could turn one of them off and get just the
       | music, or music and instructions, or just instructions.
       | 
       | Another chapter was jokes (and another was puzzles) where you
       | could step frame by frame (it used constant angular tracking if I
       | recall right) and fit dozens of them in a few seconds of time.
       | 
       | It was one of the "I wish they did more with that format."
       | 
       | The Star Wars one I later used in a computer graphics project in
       | college with another guy in the lab. We were able to get the
       | frame by frame video capture of the Death Star blowing up and
       | then use that to map to a user controlled rotating cube. The key
       | thing was getting a frame by frame image capture since we didn't
       | have the compute to be able to capture a live stream and capture
       | off of VHS would have resulted in inconsistent durations for each
       | frame.
       | 
       | Anyways... some memories of laser disks.
        
       | aspenmayer wrote:
       | Previously/Related:
       | 
       | The Person Saving The Media You Love Is You
       | 
       | https://news.ycombinator.com/item?id=40177657
       | 
       | https://aftermath.site/the-person-saving-the-media-you-love-...
        
       | riffic wrote:
       | there's probably room for another analog format to return but
       | with updated manufacturing process and todays materials.
        
       | fendmark wrote:
       | I started collecting Laserdiscs a few years ago after having
       | grown up with them as a kid in the 90s (we only rented them,
       | because new laserdiscs were expensive!) - With the inflated cost
       | of used Vinyl these days, it's been fun collecting Laserdiscs of
       | my favorite movies for their artwork and form factor to display
       | alongside my record collection at a fraction of the cost of
       | Vinyl. Also it's a weird hobby that I find hilarious to tell
       | people and see their reaction. Most people don't even know or
       | remember what a laserdisc is/was. Anyone else love Seinfeld's
       | Laserdisc joke on the last episode of Curb? Who says Laserdiscs
       | aren't cool?
        
         | MisterTea wrote:
         | > we only rented them,
         | 
         | I dont remember many, if any mom&pop video stores carrying
         | them. Was it Blockbuster?
         | 
         | And I had a friend with a small LD collection and Pioneer
         | player who shit-canned the whole thing when he moved few years
         | back. I told him why didn't he ask if anyone wanted them and
         | his response was it was worthless junk...
        
           | fendmark wrote:
           | There were a number of smaller rental shops in the Chicago
           | area that carried them. Family Video comes to mind. I don't
           | believe the Blockbusters by us ever had them.
           | 
           | I still have my laserdisc player, they are becoming a harder
           | to find item for reasonable prices for sure.
        
             | MisterTea wrote:
             | Not long ago, maybe 5-6 years, a friend moved and in the
             | process canned his small LD collection including a working
             | Pioneer player. He said it wasn't worth keeping them and
             | didn't think anyone would want them :-( I forget all the
             | titles he had but they included GoldenEye and Terminator 2.
        
       | electrosphere wrote:
       | I have a similar relationship to MiniDisc. I will never sell my
       | collection and I still use it now and again when the urge strikes
       | me.
       | 
       | I remember in the mid-1990s a friends brother was a big film
       | buff, he showed us RoboCop on LaserDisc - the original directors
       | cut. I remember being very shocked at the scene of Clarence
       | Boddicker and his cronies shooting up Officer Murphy. But on the
       | upside, I do remember being impressed with the sharp picture and
       | Dolby Surround mix compared to VHS tapes.
        
         | rbanffy wrote:
         | It's a shame MD Data was too little too late.
        
           | SpecialistK wrote:
           | And just such a pointless distinction - why not allow regular
           | audio MDs to also store arbitrary data, and then push the
           | format as a competitor to Zip disks?
        
         | dstrand wrote:
         | I love my minidisc player. My first real reason to own an
         | optical cable - 12 year old me was very cool.
        
       | mattl wrote:
       | I always remember the back alley scenes in Back to the Future
       | part 2 where you can see stacks of them in the trash.
       | 
       | https://imgur.com/a/rWkJRSa
        
       | mikepavone wrote:
       | I find LaserDisc to be a fascinating format. The base format is
       | analog, but the surface of the disc only has two possible states:
       | a pit or a land, just like CDs. To make this work, the various
       | analog signals (composite video, left analog audio and right
       | analog audio) are frequency modulated with different carriers.
       | This moves all the information into the frequency domain so the
       | amplitude is no longer significant. The combined RF signal is
       | then used to determine which areas should be a pit or land based
       | on whether the signal is above or below zero.
       | 
       | The way digital audio was added is also interesting. It's based
       | on audio CD technology which is a purely digital format using EFM
       | (eight to fourteen modulation) to encode bits on the disc as pits
       | and lands in a way that can be reliably recovered (direct
       | encoding is problematic because you need a sufficient number of
       | level transitions in order to do clock recovery and probably for
       | some other reasons I"m not aware of). It turns out that there is
       | a bit of unused RF spectrum below the lowest carrier of the
       | analog signals. On NTSC discs this gap is almost big enough to
       | fit CDDA EFM when viewed as an analog signal, so they basically
       | just reduced the sample/data rate slightly to make it fit and
       | then mix in the EFM to the analog RF as if it were another analog
       | FM signal. On PAL discs, the gap was too small so one of the
       | analog audio channels is sacrificed to make room.
        
       | FiddlerClamp wrote:
       | I'm surprised there's only a single mention of RCA's Select-A-
       | Vision. Basically a video record encased in a hard plastic sleeve
       | that used a needle to read the analog data.
       | 
       | Clever concept, but doomed to failure by digital formats.
        
       | pmlexa wrote:
       | Ahhh, I miss the early 90's and these being in classrooms....
        
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