What is laserdisc CAV?

[Starion]

Hi, I noticted that some laserdiscs packages like Bambi, The Little Mermaid, Citizen Kane and Star Wars Trilogy come in a CAV package or format. What is CAV? Is it a disc format? Or is it something that indicates that the package contains extras?

Can any laserdisc player play CAV discs, or do I need to buy a special player?

I couldn't find any information on the internet or a thread. If anyone knows of some threads, feel free to post them.

I don't know a lot about laserdiscs. lol

[Maerj]

There were two different types of laserdiscs. They were CAV and CLV.

The CLV Discs (CLV stands for Constant Linear Velocity) could hold up to an hour on one side. On some players, you would be unable to freeze frame or to do any special effects while watching the movie, but that sacrifice allowed you to have a standard 2 hour movie on a single disc.

The CAV Discs (CAV stands for Constant Angular Velocity) could only hold up to 30 minutes per side, but it was the highest possible quality video at that time. It did allow a variety of special effects such as freeze frame, strobe motion, still picture with sound, etc., depending on your player. Some players even had still picture with sound as a feature.

Most players in the later years did allow special effects in either format. Think of the CAV discs as storing each frame, one at a time. Each frame on a LD was assigned a number and you could access each frame individually. Some players also had a Jog and Shuttle wheel that would allow you to shuttle through movies at any speed you want, forwards or backwards without picture loss like VHS has.

[Starion]

Thanks Maerj! You know a lot about laserdiscs. I'll go read about the different formats now.

[littlefuzzy]

CAV Laserdiscs could be used to store information on individual frames, like a collection of the art at the Louvre Museum, or the marketing photos on the Snow White box set. The viewer would hit the frame advance button to see the next frame. There could be 65,000? separate frames with information on each one.

[Starion]

Ok, thanks. I remember reading that CAV discs store information about each frame.

[Mr. Toad]

And then they all died of disc rot.

[Starion]

Oh on, I want to watch the discs without damaging them. I already won the bid and sent the money in. I guess I'll just keep the discs inside their box without watching them.

[Maerj]

You can watch your discs Starion, they'll be okay.

[Mr. Toad]

I believe time is a much bigger factor than use when it comes to disc rot.

[The Lizard King]

I believe time is a much bigger factor than use when it comes to disc rot.

Since the last LD was produced in 2001 and laser rot manifests itself within the first two years of a disc's manufacture, chances are very good that if the disc is rot-free now, it will be rot-free forever.

Please don't scare Starion with wild (and unsubstantiated) claims. Stick with commenting on topics that you actually know something about.

TLK

[Starion]

Thanks for the info everyone. I'm going to read more about angular velocities now. Maybe I should take a physics course. j/k Wait, my University doesn't offer one. Um, nevermind.

If I can't find a laserdisc player, I'll just watch the Lion King Deluxe VHS set that I ordered. Hehe.

[deathie mouse]

I think there's LD players on E-bay

ok CAV came first. One revolution of the disc = 1 full frame. If you look at CAV sides you can see the start of the frame in the reflective pattern even (Since LDs are analog video, the LDs pits are similar in a sense to vinyl LP grooves so you can see patterns on them and stuff. ( And if you used the Krell mind expanding device you probably could read them with your naked eye )

Since each frame is coded and can be individualy accessed you have full motion manipulation and search control. Still frames, the various slow motions, 2x speed play and 3x speed have complete fluid motion forward and reverse in full* resolution. *more about this see below

Since a CAV side has a 30minute capacity and NTSC video runs at 30 frames per second (or 60 fields ) 30 x 60 x 30 CAV disc can hold aprox up to 54,000 frames per side (108,000 per disc) Since LDs don't use compression these are all individual full frames.

It's very easy to access them as they have numbers assigned to them. So if you have an index, or write a specific frame number for later viewing you can just punch it on the remote and voilá you're there. Some of the better remotes have a jog wheel that you can use back and forth to examine the frames or motion prescisely like in a real moviola. Excellent for studying animation or special effects and stuff!

As i've mentioned acouple of times the 2x fast play and 3x fast play are very cool cus they're totally fluid and for example make a movie's motion look as it was shot at 48 fps (2x) or 60fps (3x) (yeah yeah i know 24 x 3 = 72 but the NTSC system is limitted to 60fields per second you cant go over that, and besides 60fps is practically the eyes limit of motion resolution ) So things look more lively hypereal similar to being shot on live video or Douglas Trumbull's 70mm 60fps Showscan process and i know, it's only rock'n roll and i like it like it
Great to watch slow motion sequences or Star Destroyers chasing stuff

If you look at the CAV revolutions you'll realize that the the inner revolutions (the first frames) are much smaller in diameter that the outer revolutions (the end of the side) What this means is as the side progresses the image quality improves (less noise moh sharpness )

I mention this cus were gonna talk abut CLV discs now

CAV has all this cool advantages but one disavantage: only 1 hour per disc
So that's why CLV was invented subsequently. It packs the video in a different manner and you get more playing time (60 minutes per side, 2 hours per disc) This was done to minimize playing interruptions and after automatic side changing players were introduced the interruptions were practically eliminated except for longer than 2 hour movies. (Sometimes, if a movie is longer than 2 hours they do a CAV/CLV hybrid. Let's say a 140m movie: they'd put one side on CAV (30m) and the other 2 on CLV 110m) so you'd get the climax or some cool part in full manipulative CAV ("The train wreck is in CAV! The train wreck is in CAV!" the magazines would proclaim about the Tommy Lee Jones/Harrison Ford The Fugitive LD and the CAV side was at the beginning of the movie )

Now on a CLV disc the frame is encoded in the same amount of space at the beggining as at the end (as opposed to CAV as i mentioned above) so a CAV disc can have a littler image advantage quality over a CLV one too after a few minutes into the disc side as explained.

When CLV discs were introduced you couldn't do SFX motion manipulation on them as you could with CAV dics cus the frames weren't coded the wholesome 1 rev per frame way they are on CAV.
But soon players with digital frame buffers were introduced and you could have all the motion goodies and still frames (this feature is called something like Digital Video Effects)
The motion may not be as fluid in all modes/speeds but it's there.

And now we've reached the *see below The still frames and motion manipulated speds on the CLV digital buffer are not full resolution frames, their vertical resolution is halved to prevent NTSC interlace flicker/combing from showing up. But this is also the usual way still frames/motion manipulation is shown on VHS tape decks and also various DVD players when playing non progressive coded DVDs or DVDs with live shot/edited interlace video. CAV discs (and progressive coded DVDs) show the full resolution

On a CAV laserdisc when you motion manipulate, they always** show you the full 486 vertical scan lines at once so you don't loose ANY resolution. But if for example you were watching a live videotape programme if you paused in still you'd see the alternating 1/60th of a second interlaced video fields flickering alternately on your interlaced TV. Which is the way video is recorded. (remember the 3:2 pulldown? Film based material has also the interlace flicker every other frame cus of it) The easy solution when motion manipulating video is to halve the vertical resolution (discard a field) and duplicate the remaining field which is what's done automatically on CLV digital effects mode or VHS decks or DVD plyers when playing non progressive-flag coded DVDs
(**The LD players also have a button to do this vertical halving to 243 vertical scan lines manually if you wish for watching CAV discs when motion manipulating interlaced videotape programmes if they flicker and it bother you (the manual says something like "When playing certain discs in still mode if the image flickers you may use this button to minimize the flicker". The button is also good for seeing the effect of halving the vertical res on a pic too, even if it doesnt flicker )
CAV discs made from movies (film based) of course don't need to use the button cus they have the full movie frame "progressive flag" encoded. Cus they are CAV duh ) (it's ten times easier to show this on a TV than to write about it! )

When in normal playback all this interlace giberish pressent in all video formats is usually masked by the interlace scanning on normal TVs so of course the full vertical 480 to 486 scan lines (576 on PAL) are shown in video devices which is the normal thing ya know so you probably aren't aware of all this interlacing artfacts that would show really obvious when you play video slower if the players/disc didn't do all this digital time warping/halving or the progressive DVD/CAV frame flagging
Of course after you've watched lots of stuff on progressive displays when you may go back to interlaced ones you may end seeing the interlacing gibberish even on normal playback, cus your eye has seen better!

one further tangential side note in this vertical res halving issue: many progressive display/system when encountering PAL discs or NTSC discs that have video not-progressive-flagged/coded, when trying to convert the video to the progressive display, just do this vertical halving of the res So depending on the system a Pal disc (since PAL dont have/need 3:2 pulldown, many movie discs dont have the progressive flag turned on) might end up halved 576/2 = 288 pixels while an NTSC disc since it HAS to be flagged to discard the extra 3:2 frames) will be shown with the full 480, looking "better". But it's not true Same with live interlaced video tape shows or concerts, they might end up 288 or 240 (480/2) (duh ) and actualy the dvd is much sharper than you're seeing it. Depends on the progressive hardware/software (the dethi of course uses a system that shows the full 576/480 all the time ) (but of course)

What does all this have to do with CAV laserdiscs? Well CAV laserdiscs are the grand daddy of progressive frame flagging. So they rock


about laser rot well in the off chance if you ever get a disc that seemed to be starting to rot you can always "archive" it then and there... otherwise return to seller as defective.
For $6 i'd keep the deluxe box and cool stuff and hang the discs as decorative Adamantium records or as DVDs from Jupiter (Impress your gullible friends!) in case they were a total wreck
Laser rot looks at the begining like film print dirt, except it's white and/or colored (like flecks or specs that dance randomly ) I'd say 1% of my collection had rot and it's usually one freaky side of a disc not all sides so if it was an important-need-to-have-the-title and had a side affected maybe you could alway buy a second copy nowadays as they're relatively cheap and see if you get the evil side free of sin

Watching them doesnt damage them cus thei're read by a Laser so they dont wear. (Like DVDs).
The rotting thing is a chemical rection caused by ambient conditions and errors in manufature
so heat, exposure to air (oxigen), light and humidity would be the factors that would accelerate aging as with most things in life

Keep LDs DVDs CDs books negatives and Lps in a cool dark dry place

And your home theater room air conditioned

Or you can be like the rich dude on the Simpsons and build a nitrogen filled humidity/temp controlled vault chamber. But then one day you'll have to eat them discs when you end up locked with them to get your daily dose of aluminium.



So ye looking for a LD player eh?

Well if you're gonna watch the movies as movies (continuously non stop) you may want a side changing player. If your gonna buy other non CAV discs later on and you wanna watch manipulating their effects you need a Digital Special Effects player.

If you're gonna watch ocassionally or are gonna archive it you may not need those features

If you want to listen to DTS laserdiscs the player has to have a direct digital output (like CD players/DVD players do etc) (Jurassick Park in DTS is awesome! LD DTS is the full movie bit rate! ) You then can also listen to the Stereo Surround Linear PCM Digital tracks (which of course are uncompressed, sounding better that compresed 13 to 1 DolbyDigital 2.0 soundtracks ) connected to your Digital receiver directly if you want to.

If you wanna listen to the Dolby AC-3 5.1 tracks (AC-3 is known today as DolbyDigital :-p) you need a player with a AC-3/DolbyDigital RF output thingue thynchumagog (some players (or dolbydigital receivers) came with the whole stuff some had to have an extra adapter thibnguie added in between to connect maybe another LD manning UD member can tell us more about that stuff (My LD player is from before Dolby AC-3 was added to the LD spec)

There are some other features to look for like S-Video output (but if your display's chroma separation filter is more advanced than the one on the LD player, conecting it through the regular RCA video out jack would give better results) and TBC (Time Base Coreector), etc
Adjust your budget acordingly.

Of course a remote with jog wheel is great for all that Lion Kingish animation frame studying (watch the words SFX coalesce back and forth! )

Pioneer was the main maker of the players and a presser of discs so maybe inclinate towards that direction unless you get a great deal on other brands

hope this helps


if you find mvealf's super duper high def LD player send it to me for.. "ahem".. evaluation.

[2099net]

( And if you used the Krell mind expanding device you probably could read them with your naked eye )

But out for monsters of the mind!

[Starion]

deathie mouse, you should write a book about laserdiscs. Thanks for the information. I'll try to follow you tips.

I gotta go. Bye