What types of laserdiscs are there? (1 Viewer)

[Anders Englund]

I working on a new version of MoCaSys, my movie DB software. Hopefully, I'll make you all switch from DVD Profiler (no luck so far).
However, I need to know the different tpes of LDs there are. The only one I know is CAV.
--Anders

 

[EricK]

Anders

LTNS on here! How have you been?

there are also CLV laserdiscs that can hold approx 1 hour of video and audio to a side. CAV was 1/2 hour to a side...

Hope that helps!

Eric.

 

[Grant B]

there are 8 inch LDs besides the usual 12 inch ones

High Definition Muse LDs from Japan

Pal and NTSC LDs

AC3, DTS PCM and analog sound

There are also CED discs which are not laserdiscs

CAV= Constant Angulat vELOCITY

CLV= Constant Linear Velocity

hope this helps a little

Where is Rachael????

 

[bob kaplan]

...it has been so long since i researched this but i think

CLV (constant liner velocity) disc held an hour of programing per side....but were subject to a problem called crosstalk. i think was a result of the laser reading two tracks at once.

CAA (constant angular acceleration) held a bit less (3 or 4 minutes at the most) less per side than CLV but were less subject to visable cross talk.

...hope memory serves correctly.

 

[Rachael B]

I's auh'comin' Grant. There are some LD's that are labeled CD Video. I think the CD Video designation was more common in PAL Europe. The only one I remember in my collection is: The Who, WHO'S BETTER, WHO'S BEST on the Polygram PMV label (080 345-1), 1988. If you look at the list of discs that Pioneer LD players will play in their manuals, CD Video is always on the list, sometimes it says CD Video LD, which it should to distingish it from 5" CD Video discs. My 12" Who disc is just labeled CD Video.
There are also 5" CD Video discs that can have up to 5 minutes of video and up to 20 minutes of audio only. This was a short lived format. It was an attempt to sell music videos in the late 80's and early 90's.
VSD (Video Single Disc) is a 5", five minute video disc. I've never seen one. I suspect it was a Japanese format. The five inch formats only play in CLD players, that's players that have a 5" slot or drawer.
Some Japanese LD's are desgnated LD-G, G is for graphics. This just means that a LD-G capable player can manipulate the LD-G subtitle tracks.
Grant, I think we have them all now. Best wishes from Laseland!

 

[Anders Englund]

Thanks guys!

--Anders

 

[Mattias_ka]

Hej Anders! If you have any more questions you can mail me at home. Jag kan hjalpa till. [email protected]

 

[Hendrik]

...I seem to recall that at one time there were (a very few?) LDs featuring anamorphic transfers... never saw one myself, but I do own an 'old' Pioneer LD player (plays PAL discs only, reads digital soundtracks only) the remote of which includes a 16:9 button!...
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[alan halvorson]

There were some Japanese LD's that were anamorphic. Check this site out: Nick Sanitini.
This comes up now and again and I keep forgetting the details, but someone here knows it better than me. There is a link somewhere that explains it all very well - I wished I had bookmarked it.
For one thing, what has come to be know as CLV (constant linear velocity) is not really CLV. It can't really be called CLV because it isn't constant velocity! Rotational speed varies in jumps as a crosstalk-reducing technique. There are several types of "CLV" - I don't know what the differences between them are (one has been mentioned - CAA). One of them can carry up to 70 minutes a side. I'm not aware of any discs of this kind actually produced - perhaps they were difficult to manufacture or maybe players would have had a hard time reading them - but it would have been nice had this type existed.
Now, to search for the LD FAQ link ....

 

[Hendrik]

"...CLV (constant linear velocity) is not really CLV. It can't really be called CLV because it isn't constant velocity!..."
...ahh... it isn't called "constant velocity" but "constant linear velocity" ... that explains why a CLV disc (whether LD, CD or DVD) starts out at the center spinning at a very high rpm rate (short spirals) and continually slows down the closer it gets to the outer rim (increasingly longer spirals) - but: always traversing the same linear distance-per-second of playing time... a CAV disc otoh spins at a constant rpm, ergo the phrase "constant angular velocity"...
Simple, no?!
...would this FAQ site help?...
http://www.frii.com/~rjn/laser/
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[alan halvorson]

Yes, I know, Hendrik, I just forgot to add it. Here's the Laserdisc FAQ link I was looking for. Look at the 5.6 What is CAA then? section.

 

[Henry Gale]

... that explains why a CLV disc (whether LD, CD or DVD) starts out at the center spinning at a very high rpm rate (short spirals) and continually slows down the closer it gets to the outer rim (increasingly longer spirals) - but: always traversing the same linear distance-per-second of playing time... a CAV disc otoh spins at a constant rpm, ergo the phrase "constant angular velocity"...

Eh, NO, it's not simple, in fact I think it's just backward.

If I'm incorrect don't even tell me 'cause my head hurts.

Jim

My confusion may be compounded by my belief that a CAV disc displayed one frame of film per disc rotation, so it would be going faster when it reached the outer edge.

 

[Hendrik]

"Eh, NO, it's not simple, in fact I think it's just backward."
...sigh...
...with very few exceptions, ye olde 10-inch and 12-inch shellac records (ask your [great-]grandparents) 'turned' at a nominal 78rpm...
...then came 10-inch and 12-inch Long Playing records (almost immediately dubbed 'LPs' by the public at large) which 'turned' at a nominal thirty-three-and-one-third(!) rpm (and, in the case of 'talking records' for the blind at a nominal sixteen-and-two-thirds(!) rpm...
...almost simultaneously, the - originally competing and therefore non-compatible(!) - 8-inch 'single' and its sister the (45rpm) 'EP' (as in Extended Play) appeared, which 'turned' at... you guessed it!... a nominal 45rpm...
...with very rare exceptions all of these discs were read from the outside in...
...also, they all played 'constantly' at their respective nominal speed...
...I keep stressing the word "nominal" because the speeds indicated were supposed to be maintained by purely mechanical means, using various methods such as rubber discs, rubber bands, and whatnot (is that hysterical laughter I hear in the backgound?)...
...the arrival of Laserdiscs introduced the concepts of CLV and CAV...
...the reason why LDs are 'read' from the center outward is probably because of the TOC (as in Table Of Contents) which was included on each LD - and later also on each CD, and on MiniDiscs, and on CDV (as in Compact Disc Video) and on VCD (as in Video Compact Disc - which is not the same as and therefore should not be confused with CDV) and on CD-I (as in Compact Disc Interactive) and on CD-ROM and on CD-RAM and on......
...I do know why CDs are 'read' from the center outwards: CDs derived from LDs, applying CLV to sound-only discs; when designing CDs, nobody yet knew how 'big' these discs were eventually going to be, so it was decided that they would be read from the center, and their eventual size could be decided on later - as it turned out, this size wound up being 12cm diagonal(*)... perhaps in memory of and in homage to the venerable 12-inch LP?...
(*) ...there also used to be (but rarely) 8cm CDs, a.k.a. 'singles' ... and I own an 8cm DVD 'single' with a Cantonese Rap video clip!...
(...wipes the sweat from his brow and retires to his padded cage...)
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[Hendrik]

"...my belief that a CAV disc displayed one frame of film per disc rotation, so it would be going faster when it reached the outer edge..."
... no it wouldn't!... the data for a single frame of film would - in the case of a CAV disc - simply be 'spread out' over a longer (linearly speaking!) stretch of the disc as the movie progressed (think of 45rpm 'audiophile' transfers onto 12-inch LPs where, in a way, exactly the same thing happens - in analog form, of course)...
...incidentally, the true 'glory' of CAV - at least IMHO - was not really that a person could inspect a movie frame-by-frame (honestly now: how often have you actually done that?) but that a single disc side could contain literally into the tens of thousands of still images (for instance all the paintings in Washington DC's National Gallery, all the sculptures in the Paris Louvre...
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[Henry Gale]

Thanks Hendrik, even with the different colours I'm still in over my head.
The single frame count on a CAV disc is 54,000 per side. Even with that capacity the Louvre is on 2 discs.
I own the Musee D'Orsay disc (11,000 images), VIENNA The Spirit Of A City (15,000 stills) and L.A. Journal (it's an 8" disc and I'm too lazy to look for it).
These discs come with wonderful catalogues so you can look up a subject, artist or title....and punch in the frame number of your choosing. With DVD this was all lost, "like tears in rain."
Jim