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Comment by sandos | Hacker News Reader

I never knew laserdisc was analog! Wow.

LD's could also have digital PCM audio tracks in addition to the analog tracks. Some of them later on had Dolby Digital 5.1 as well as some rare discs with DTS.

Look into Hi-Vision as well, which was HD LaserDisc back in the 90s in Japan. Muse was used to broadcast really high def signals for the time.

I have a player that can play both sides without having to get up and flip - CLD-D703

Yeah that was the big difference between it and DVDs.

LDs are just the NTSC signal on the disc, the same way a CD is just raw audio on a disc (wrong! See replies). That means no compression. And given they didn’t have the higher density discs we got with DVDs they had to be the size of LPs and flipped mid movie.

DVDs were digital so the video could be compressed.

Except LDs aren’t like CDs, it’s sort of the other way around! Laserdisc came out 5 years before audio CDs. That blew my mind when I first heard it. Came out in ‘78.

Dual-layer DVDs didn’t come out until later. Long movies on single-layer (or those whose producers were too lazy to optimize compression or use dual-layer) DVD had to be flipped mid-movie as well.

Mass produced dual layer DVDs came out early on around late 1997 (maybe confusing with DVD recordable?), it’s not like the spec changed. There were some low cost distributors that couldn’t afford the equipment but the majors were stamping early on.

Besides unlike the one hour max on an LD, a 120 minute movie will fit on a single side single layer, so most early movie releases would fit on a single side single layer (the quality did suffer).

More commonly in the early days the dual side was to provide a pan and scan and letterbox option or extras.

There are so called “flippers”, but they weren’t that common.

An LD is 1 hour max so you are almost always flipping for any feature length.

It needs to be mentioned that several players moved the laser to the other side of the Laserdisc, so you didn't have to flip the disc yourself.

DVD-5 single layer, single side

DVD-10 single layer, double side

DVD-9 dual layer, single side

DVD-18 dual layer, double side

With the dual layer discs, the first layer had to be larger than the second layer. There was a slight pause when switching layers, and care was taken to place the layer break at a spot to hide that pause as much as possible. At least on the discs where the author took pride in work unlike the YT decisions on when/where to place ads. Although, I've seen some really poorly placed layer breaks too.

Fun fact, I remember my french version of Reservoir Dogs switching from first layer to the other exactly during the torture scene, with the pause you are describing. Absolutely no care taken. Or maybe to put this at the worst moment possible. What a turn down !

I don't think they came out later. They existed in the spec from the beginning and some very early long movies were a single disc (e.g., Titanic). Some movies still needed flipping or two discs, like Gone with the Wind but it's just too long.

I totally forgot flipping DVD for some movies or series, I can't recall now. Damn.

CDs are still digital though. Its more like how records are just analog audio.

I was just looking up laser disk and I never realized just how analog they were.

I always thought that they recorded the video signal the same way CDs did, in a series of bits.

I had no idea the length of the pits on the disk actually corresponded to the wave form. They’re not digital in any way shape or form.

Amazing. Thanks!

To further mess with your mind, there was a digital tape format which is more like you imagined - it is a CVBS video signal, but in PCM format. Very similar to CD audio in concept. It was used in TV studios and also found use for mastering LaserDiscs.

https://en.wikipedia.org/wiki/D-2_(video)

We had an Ampex D-2 unit that was nicknamed the dishwasher for its size. Supposedly, there was a demo of the error correction abilities of the unit where the tape had a hole punched in it yet no concealment errors visible when playing frame by frame. They also had the demo rigged up to be able to rotate the machine to be inverted while connected to scopes to show now stable the transport was. I never saw any of these myself, and only heard of these 3rd person style, hence the supposedly. It was large enough to hold a 3 hour cassette. The smaller Sony unit could only hold 2 hour cassettes

The first audio CD demonstrations were also like that. People drilling holes in the discs, smearing them with ketchup, etc., to show how reliable the system was. At least the next 15 seconds…

I remember the first time I heard a CD skipping. It was at my uncle's house. Someone came to him and said hey, the music is skipping. He said CDs don't skip. The other person said, well... whatever CDs do, it's doing that.

I really appreciated the irony of stereos (particularly in cars with subwoofers) which were loud/powerful enough to cause the CD skip. So, in a sense, the CD was causing itself to skip.

Oh I think I saw a picture of that compared to a normal VHS cassette online the other day. But I didn’t know what it was.

Yeah, the earliest ones were basically just a wear-resistant higher quality version of VHS/Beta. I had this 1982 top-loader model as a kid:

https://www.radios-tv.co.uk/1982-philips-vlp600-laservision-...

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