Laser disc is analogue or digital?

[neazoi]

Hello I have a basic question.
Are laser discs analogue or digital in nature? I do not refer to the signal after a possible A/D conversion, I refer to the signal as it is written on the disc. Is it analogue (exactly like the vinyl disc) or digital (little holes on the disc like the CD)?

[SoNic_real_one]

Video signal is recorded analog (FM modulation). Audio signal is recorded either analog and digital (PCM for stereo or DD/DTS for surround) or both.
http://en.wikipedia.org/wiki/Laserdi...al_information

Picture had a vertical resolution of 425 TVL lines for NTSC and 440 TVL lines for PAL discs (while VHS featured only 240 TVL lines). Laserdisc was a composite video format: the luminance (black and white) and chrominance (color) information were transmitted in one signal, separated by the receiver. While good comb filters can do so adequately, these two signals cannot be completely separated.
The B/W resolution of 425×480 (425 TVL) LaserDisc (440 TVL with PAL LaserDiscs) was similar with S-VHS, Hi8. The color resolution was better - LaserDisc had 120-lines of horizontal NTSC color resolution, later LD's had even higher color resolution, up to 240 lines. S-VHS and Hi-8 had 30-lines, maximum.
Video Signal-to-noise ratio of Laserdisc, typically was no more than 45dB.

[neazoi]

I was thinking of using a laserdisc as a really good analogue source for high fidelity listening.
Basically not interested in video, but just audio as a super alternative to the vinyl disc.

Just to refine my question:

In vinyl the moving of the head needle produces the actual voltage signal, which is he actual waveform. This signal is then RIAA amplified/corrected.

In Laserdisc is this the case? I think data is written on the disc using dots and dashes, which is not the actual waveform but must be somehow converted to represent the actual analogue waveform, using a D/A converter.

[juz400]

The Digital soundtracks on Laserdisc are the same format as CD IIRC
Far better Audio on what films I have compared to the DVD versions as the DVD Audio was compressed to fit..

[neazoi]

Right, so the trick is the compression here, but the real thing remains digital in nature...

[mace1337]

Laserdisc's PCM-track is no better than CD and it's analog sound vary wildly between players and discs.

All in all you're better off with CD.

[stratus46]

SoNic_real_one, you were doing real well until you veered off into the weeds with that 120 lines vertical color resolution. There is no color blurring vertically unless your TV - not the Laserdisc - has a really crappy comb filter. Granted, some early 2 line comb filters fell into that category but the 3 line units did much better. All in all, analog video is dead. YEA!

G²

[mace1337]

Originally Posted by stratus46

SoNic_real_one, you were doing real well until you veered off into the weeds with that 120 lines vertical color resolution. There is no color blurring vertically unless your TV - not the Laserdisc - has a really crappy comb filter. Granted, some early 2 line comb filters fell into that category but the 3 line units did much better. All in all, analog video is dead. YEA!

G²

Tell that to the NTSC-world still using composite cables for all their SD-stuff...

[juz400]

Laserdisc has NO compression in the Audio, I dont know about the MUSE HD laserdiscs tho.. If it wasnt so expensive to make the discs it could be still be around today.
How much compressed digital audio/video can you fit on a 12" disc?

It still does have a wow factor for people who have never seen the discs before!
`Hey nice record collection you`ve got there` pull out a disc and they are gobsmacked!

Laserdisc players can apparently make good CD transports as they are heavily built in comparison..

I still have over 250 Laserdiscs and a working player, they will not be upgraded until the player dies and isnt replacable.. DVD never did anything for me..
BluRay on the other hand, I probably will get one of those as Ive been impressed by what Ive seen/heard..

[SoNic_real_one]

Originally Posted by stratus46

SoNic_real_one, you were doing real well until you veered off into the weeds with that 120 lines vertical color resolution.

Well, when you have nothing else than analog video to compare, the 120 lines of color versus 30 on S-VHS or Hi-8 (top of amateur video back then) are making a difference. Because the signal was recorded composite, the comb filters have their importance on the TVside, but from recorded garbage (like VHS) you cannot create someting, no matter how good is your player. Bleeding of the colors over the B/W countours, due to low bandwidth of chroma channel, was the main problem of analog video recordings.

Originally Posted by neazoi

I was thinking of using a laserdisc as a really good analogue source for high fidelity listening.
Basically not interested in video, but just audio as a super alternative to the vinyl disc.

You could try to convert the audio in digital signal and record that as video on a laser disc. But... HOW will you "burn" the LD's knowing that NEVER was a home "recordable" LD disc? In the VHS world, there is the Hi-Fi audio recording, because the recording was magnetic.
Optical recording came far latter in the game, originally Sony and Phillips didn't even contemplate that one day we will be able to record CD's on our computers (that's why no encrypting was done on audio CD's).