Subject: The Laserdisc FAQ - part 2/4
Date: 5 Mar 1996 16:20:49 GMT
NNTP-Posting-User: leopold


                            LD THE LASERDISC FAQ LD
                                       
                                 II) HARDWARE
                                       
   This page is "http://www.cs.tut.fi/~leopold/Ld/FAQ/Hardware.html".
   
   This page is maintained by Henrik 'Leopold' Herranen
   
   The whole FAQ file is available at
   "http://www.cs.tut.fi/~leopold/Ld/FAQ/index.html".
   
   <-- Introduction Software -->
     _________________________________________________________________
   
   
   
7. Buying a laserdisc player

   
   
  7.1 WHAT FEATURES SHOULD I LOOK FOR WHEN BUYING AN LD PLAYER?
  
   Not written yet. 
   
  7.2 WHAT ARE ALL THE DIFFERENT OUTPUTS ON THE BACK OF AN LD PLAYER?
  
   From Bob Niland's (rjn@csn.org) LD#01: ..but it can't even record?,
   updated by Leopold.
   
   Video, or CVBS, or composite video
     * All players provide a composite video output, which uses the
       "video" or "aux" input on the TV/monitor. Contains no audio. This
       is usually a yellow-coded RCA female phono jack.
       
   RF, or using antenna connector
     * Some consumer players also provide an RF (radio frequency,
       "channel 3/4") output. The RF video signal quality is often
       visibly degraded from the composite. Contains mono audio. This is
       usually a female threaded F-connector.
     * Caution: Some players, such as the entire Pioneer CLD-xx90 and
       later series, omit RF output. If your TV doesn't have a "video"
       input, you'll need to either route the LD's video output through
       your VCR's video input, or buy the LD player's optional external
       RF modulator.
     * Using RF connectors should be avoided, because of the inevidable
       loss in picture quality.
       
   Y/C, or S-Video
     * Mid-range and high-end players often provide a Y/C (component or
       separate luminance/chrominance, aka "S-Video") output, but its
       value is debatable.
     * The native signal format on LD is composite, so Y/C output is only
       worthwhile if the Y/C separator circuit in the LD player is more
       sophisticated than the one in the TV/monitor, and the TV is
       accurate enough to tell. The Y/C output contains no audio.
       
   All players have at least one set of 1/L(eft) and 2/R(ight) RCA audio
   output jacks with which to feed an external amplifier and speakers.
   The RF (CH 3/4 radio frequency video) output contains either L+R or
   the currently selected audio channel. Some players also have on
   optical digital output for sound, and the AC-3 capable players have an
   AC-3 RF output. 
   
  7.3 HOW ARE KARAOKE PLAYERS DIFFERENT THAN REGULAR LD PLAYERS?
  
   From Bob Niland's (rjn@csn.org) LD#01: ..but it can't even record?
   
   Karaoke is a Japan bar/nightclub craze in which inebriated patrons
   sing the lyrics to instrumental pop tunes. Laser Karaoke players are
   normal players plus five features:
     * they have a microphone input so that you can sing along with the
       on-screen lyrics of laser karaoke discs,
     * they often have pitch control, and
     * they have a vocal-killer circuit that blends the two stereo
       channels in opposite phase, has a voice-band notch filter, or uses
       Pro-Logic style DSP to cancel front-center signal, which generally
       eliminates or dramatically reduces the lead vocal on regular
       non-karaoke CDs and LDs.
     * they often have reverb and other enhancement processing for the
       microphone input.
     * they may have a CD+G decoder to extract the sing-along lyric text,
       and mix it with the video signal.
       
   
   
  7.4 WHICH LD PLAYER SHOULD I BUY?
  
   The amount of space that would take up prohibits its inclusion in the
   FAQ. (((For a good beginner's guide to buying LD players, refer to
   Phil Kim's articles, available by e-mailing Phil at kimp@rpi.edu or by
   checking out his WWW page at http://www.rpi.edu/~kimp/ NOT WORKING))).
   
   
   Here I just want to say that if you are living in a PAL country, you
   probably want a player with NTSC playback capability. Otherwise you'll
   be in deep trouble trying to find programs for your nice player.
     _________________________________________________________________
   
   
   
8. Tech tweaking

   
   
  8.1 WHAT ARE COMB FILTERS? WHY DO I NEED ONE?
  
   The LD video signal is often referred to as a "composite" signal,
   which means that the luminance (Y) and chrominance (C) information are
   not sent separately, but rather in the same signal. It is the
   responsibility of the receiver of a signal to reseparate these
   signals. This task is not very straightforward, and so-called comb
   filters are used to do the separation.
   
   (If anyone wants to give a better explanation of the above in good
   English, feel free to post it to me at leopold@cs.tut.fi)
   
   The following is an article sent by Dave Martindale (davem@cs.ubc.ca)
   (96-02-17):

>So what exactly is adaptive, or 2-dimensional, or 3-dimensional about
>a Y/C separation filter? Seriously. I'm not exactly up on the latest
>cutting-edge technology, and these descriptions just don't conjure an
>image in my head.

   The first dimension is horizontal, along one scanline. The second
   dimension is vertical, looking at pixels above and below in the same
   column. The third dimension is along the "frame" axis, looking at the
   same pixel one entire frame later.
   
   A 1-D filter would have to separate Y and C looking only at changes
   within one scanline - i.e. frequency alone. So anything in the
   frequence range from about 3 MHz up is likely to be considered chroma,
   while below 3 MHz will be considered luma. This has lots of problems
   in confusing luma with chroma.
   
   A 2-D filter has at least 1 scanline of memory, so it can perform
   comparisons in the vertical direction as well. The structure of the
   NTSC colour encoding is such that, if the RGB values remain constant
   within a column, the luma remains unchanged from one scanline to the
   next within the field, while the chroma component undergoes a 180
   degree phase shift. If you add two adjacent lines from one field
   together, the chroma components cancel, leaving only luma. You can
   then subtract this luma from the original signal to get chroma. The
   frequency response of this sort of filter looks like a "comb", with
   many teeth located at the odd harmonics of half the line frequency,
   which is where the chroma information is. That's why it's called a
   comb filter. It's 2D because it works on a 2D array of pixels.
   
   The simple 2-line 2-D filter I described above has some problems of
   its own, and it can be improved by looking at 3 lines simultaneously
   (a 3-line filter), and also by changing the filtering algorithms
   depending on whether this area of the image seems to be moving or not
   (a motion-adaptive filter). But it still gets some things wrong. For
   example, it creates "hanging dots" at sharp colour transitions on
   horizontal edges - the large change in chroma content could either be
   fine luminance detail appearing, or a large change in chroma. The
   filter decodes it as the former, but it's wrong.
   
   A 3D filter needs to have enough RAM to store a complete frame of
   video or more, so comparisons can be made between the *same* pixel at
   2 or more different times. This takes advantage of the fact that the
   luma component remains the same from one frame to the next (assuming
   no change in picture content) but the chroma has a 180 degree phase
   shift. The extra information lets the 3-D decoder get the decoding
   correct in a wider range of situations if the image isn't changing,
   but also introduces new ways for it to be wrong if the image is
   changing. Thus, it's important for the filter to be able to detect
   motion and avoid doing some of the filtering in such cases.
   
   But in the stationary-image case, each output pixel depends on the
   values of a 3D array of input pixels. 
   
  8.2 DOES S-VIDEO OUTPUT IMPROVE THE PICTURE QUALITY?
  
   Perhaps.
   
   An S-Video cable is a cable that can send the luminance and
   chrominance as separate signals from a LD player to a TV set.
   Unfortunately, because the video signal on LDs is composite video,
   there is in principle no sense in using an S-Video cable to connect
   your LD player to your TV set.
   
   However, if the LD player does some clever tricks to the video signal
   before transmitting it, like noise reduction, it has to separate the
   luminance and chrominance information anyway, and it is saner to keep
   them that way all the way to the TV set. Also, if the comb filter of a
   LD player having an S-Video connector is better than the one in your
   TV set, it is wise to use an S-Video cable.
   
   So, if you use an S-Video cable between your LD player and TV set, you
   will lose only if the player does no clever image manipulating and
   your TV set has a better comb filter than your LD player.
   
   The reality of mid-range and low-end LD Y/C is that some folks report
   that Y/C is a tiny bit better than composite, some can't see a
   difference, and some report that Y/C is slightly worse. Try it
   yourself if you are interested. 
   
  8.3 WHAT IS "LD101: A VIDEO STANDARD"?
  
   Excerpted from Bob Niland's (rjn@csn.org) LD#93: A test tool that
   never needs calibration Revised: 16 Jan 92
   
   "A Video Standard", the Reference Recordings LD-101 laser video
   test/demo disc was released in May 1989. The list price was $59.95 and
   is now 69.95 (but has expanded booklet). LD-101 is available from most
   LD retailers, all non-club mail-order sources and in the US directly
   from Reference Recordings, Box 77225X, San Francisco, CA 94107 (415)
   355-1892. In Canada, MAW Audio (514) 651-5707 is supposed to stock it
   ($99CAN+7%GST).
   
   If you own or plan to own a laser videodisc player, are serious about
   video image quality, and don't own a roomful of NTSC test and pattern
   generation equipment - investigate this disc.
   
   According to the jacket, most of the video material was created and
   edited in the digital (video) domain and not converted to analog until
   disc mastering. Both digital and analog sound is provided (not always
   the same, either), and the analog trips CX on and off at various
   times. Mono, stereo, Dolby Surround and Dolby Pro-Logic Surround
   material is included.
   
   There are eight chapters and around a hundred still frames. Few of the
   stills are stop-coded, evidently to prevent interruption of the audio
   program. All of the stills are cataloged in the new instruction
   booklet.
   
     * Chapter 1: "Video Control" - Introductory digital video and
       animation.
     * Chapter 2: "Studio Video Production" - Setup tests in a video
       studio.
     * Chapter 3: "Electronic Field Production" - Stills concerning Sony
       Betacam.
     * Chapter 4: "Transferring Film to Video" - Begins with stills of
       the Rank- Cintel flying spot scanner and frames describing 3-2
       pulldown.
     * Chapter 5: "Audio Demonstration with Video Test Signals" - The
       useful stuff.
     * Chapter 6: "Audio Test Signals" - Over two dozen steady-state and
       swept audio signals, L, R, L+R, L-R (for Dolby).
     * Chapter 7: "Monitor Calibration Test Signals" - More stills.
     * Chapter 8: Credits
       
   
   
   With this disc, and your TV/monitor's service manual, and CONSIDERABLE
   CARE if you need to open the TV/monitor... (WARNING - LETHAL VOLTAGES
   ALL OVER THE PLACE!) ...you can adjust for correct geometry
   (especially overscan), white level, black level, color balance, color
   intensity, "sharpness" and other tweakable parameters.
   
   LD-101 is also useful for testing LD players, TV/monitor/displays and
   surround decoders, if you are in the market for any of these items. 
   
  8.4 WHAT IS THE THX - WOW DISC?
  
   Much noise about nothing. Just some Lucasfilm movie clips and lots of
   market hype. Forget about it. It's not worth the $100 people are
   asking for it. Buy A Video Standard and some good movies instead.
     _________________________________________________________________
   
   
   
9. Can I modify my player to get these features?

   
   
  9.1 AC-3 RF OUTPUT
  
   Interestingly enough, an AC-3 RF output can be added to absolutely any
   player with minor technical skills and $5 worth of electronic parts,
   even if your LD player is an old analog-only one!
   
   You will need the schematic for your player and access to WWW. On the
   Web page " http://users.aol.com/chunter/ac-3mod.html " you can find
   complete instructions on how to make it. The author of this FAQ has
   seen this modification done on a Pioneer CLD-2950 multistandard
   player, and it works perfectly! 
   
  9.2 TRUE NTSC OUTPUT FOR PIONEER CLD-1450
  
   For this, have a look at " http://www.cs.tut.fi/~leopold/Ld/CLD1450/
   ", and you'll have a true NTSC output and AC-3 RF output in your
   player in just a few hours.
     _________________________________________________________________
   
   
   
10. Care and maintenance of laserdiscs

   
   
  10.1 WHAT IS THE ABSOLUTELY BEST WAY TO PRESERVE MY LASERDISCS?
  
   Excerpted from Bob Niland's (rjn@csn.org) LD#13: The care and feeding
   of laser videodiscs
   
   The following narrative of LD care is in life-cycle order. The part 1
   scenario presumes that you have just bought a disc. If it is a
   factory-new disc, or still in print, and can be exchanged, I do NOT
   recommend the part 2/3 repair procedures (not listed in this FAQ).
   Exchange the disc.
   
   Disclaimer: These are the practices that I follow. The industry at
   large doesn't seem to have any. These practices are not warranted in
   any way whatever, and this series of articles is partially intended to
   provoke discussion and counter-suggestions.
   
   Prerequisite: you need to know that the video data for side "X" is on
   the opposite side of the platter from the label for side "X". Also,
   LDs play from the inside to the outside.
   
   Myth: LDs are indestructable. You can handle them anyway you like. The
   laser can read right through fingerprints, smudges and scratches.
   
   The myth is false. The laser has a limited tolerance for optical
   obstructions. If you can see damage (or defects) in the acrylic, there
   is a strong possibility you will see video noise on the screen. LDs
   are not as robust as CDs. 
   
    10.1.1 Buying a laserdisc
    
   If you live some distance from your LD store, you might consider
   opening purchases and checking them on a store player.
   
   If buying a used disc, check its contents. Compare the platter labels
   (and side count) to the jacket art, and make sure some sleazy customer
   has not switched old all-CLV analog pan&scan platters for the CLV/CAV
   digital widescreen ones you paid for. 
   
    10.1.2 Remove the shrink wrap
    
   Remove the shrink wrap. Over-tight wrap is the leading cause of "dish"
   or "cone" warp, where the disc describes a shallow cone when placed on
   a flat surface. Do not store LDs in their original taut wrap.
   
   If the wrap is the traditional taut variety, carefully slice it along
   an opening in the underlying slip case or box. Peel it off, taking
   care to avoid ripping any stickers affixed to the wrap. Save the wrap
   for the moment.
   
   If the wrap is the loose slightly oversize variety common on Japanese
   imports and IMAGE/Kuraray production, consider using it as the outer
   storage sleeve. Cut carefully and evenly along the top, removing as
   little plastic as possible. 
   
    10.1.3 Inspect and sample
    
   Inspect and play (sample) the disc. Before investing any more work,
   make sure there are no defects.
   
   Remove any stray dust particles or hair with a soft lint-free cloth.
   Inspect the disc surfaces for gross dangerous defects, like severe
   warp, side-to-side mis-alignment and cracks. If any - DO NOT PLAY.
   
   Sample the disc. Turn on "DISPLAY" to show the chapter number and
   time/frame. Play the sides in order, paying some attention to the
   program content and chapter.
   
   If it is extensively chapter-marked, skip through by chapter. If not
   chaptered, play the start of each side, and seek to 11:11, 22:22, etc.
   When one of the seeks takes you to the end of a side, back up and
   watch the end of the side. Problems are usually most prominent there.
   
   Find a problem? I have a separate article available, LD#17, "LD: What
   is a defect?" (For a condensed version, see section 11-1 of this FAQ).
   
   
    10.1.4 Upgrade the inner sleeves
    
   Upgrade the inner sleeve(s), also known as "liners". The U-shaped,
   unreinforced plastic variety provide inadequate protection. They
   collapse, leaving exposed arcylic to rub against the cardboard jacket.
   
   
   Use poly-lined paper-reinforced rectangular sleeves, with center holes
   that allow reading the labels on both sides. I order them from
   Starship Audio-Video, but Radio Shack catalog# 42-132 sleeves will do.
   Reinforced sleeves are particularly important for multi-platter sets
   that are in single-slot jackets or boxed.
   
   If the disc already has a quality sleeve, but was used or a rental,
   you might want to replace the sleeve anyway. It may be coated with
   food oils and salts left by popcorn-eating renters. 
   
    10.1.5 Disc insertion
    
   Always handle the disc by the outer edge and/or inner (hole) edge.
   Never touch the data surfaces. Handle the disc with clean, dry hands.
   Even if potato-chip/popcorn fingers don't touch the data surface, they
   will touch the inner surfaces of the sleeve, and the sleeve will
   transfer the oils and abrasive salt crystals to the disc.
   
   Insert the sleeve into the jacket with the sleeve opening UP, not
   facing out the jacket opening. Don't give the disc a chance to roll
   out onto the ground and crack. 
   
    10.1.6 Outer sleeve
    
   For ordinary use, I store my discs (in their jackets) in resealable
   polypropylene sleeves or ordinary polyethylene outer sleeves,
   available at most used LP stores (and LD mail order houses).
   
   For transport and loaning, I use a small number of LD-size PVC ziplock
   bags, obtained from a regional LD sales and rental store. PVC sleeves
   are on the market under several brand names, such as "LaserShield". I
   do not recommend the use of PVC (polyvinylchloride) for long-term
   storage of anything, including LDs. PVC outgasses vinyl chloride over
   time, which can attack metals and other plastics.
   
   The purpose of the poly sleeves is to prevent damage to the jacket
   artwork and minimize air circulation if you live in a humid climate.
   In a normal storage cabinet, the insertion resistance is high enough
   that unprotected, the jacket art and text will eventually be scuffed
   away. The zip sleeves prevent the disc from sliding out of the sleeve
   during transport.
   
   Holding the jacket in the normal horizontal position insert it in the
   outer sleeve with the sleeve opening up. As with the inner sleeve, the
   openings are at right angles to each other, preventing the disc/inner
   sleeve from sliding out accidentally. 
   
    10.1.7 Store the disc properly
    
   Attributes of a reasonable storage cabinet are:
     * Stable temperature - in particular, never let sunlight fall on the
       cabinet or the discs. If possible, 10 degrees C is recommended.
       Acrylic plastic begins relaxing at 60 degrees C, and glasses at
       90C.
     * Low humidity (30% RH) - acrylic plastic is hyrgoscopic, and tends
       to warp when wet. Water vapor can infiltrate, leading to trouble
       down the road, particularly if your air is polluted. If you live
       in a humid climate, and don't have a dehumidified room, at least
       keep the humidity stable.
     * Store the discs vertically (not horizontally), and pressing
       lightly against each other. Make sure that the surface or bookend
       at each end of the stack presses evenly against the entire face of
       the end LDs, otherwise, warps are likely.
     * Save cardboard fillers from LD mail orders. They make great
       cabinet spacer material to prevent disc stacks from leaning.
       Leaning can result in warp.
     * Play (or at least sample) the disc once per year. In addition to
       catching any decay early, this will probably reorient the disc in
       the sleeve, preventing the plastic flow of arcylic that can occur
       over geological time.
       
   Keep the discs in storage when not in use. Keep them away from pets,
   sunlight, radiators, hot/warm audio/video equipment surfaces and other
   destructive forces. Don't leave a disc in the player overnight:
   running, paused or stopped. 
   
    10.1.8 Playing the disc
    
   Observe the handling precautions listed earlier.
   
   If the player has disc support pads in the data region of the disc
   (and many do), lower the disc vertically onto the pads without sliding
   or spinning it. Also, periodically inspect the pads for the presence
   of abrasive debris; vacuum up any found.
   
   If stopping play and ejecting the tray are two separate operations on
   your player, always wait for the disc to completely stop spinning
   before ejecting. I have seen CDs destroyed by players that dropped the
   CD, still spinning, onto in-data-area supports.
   
   Always remove the disc from the player, return it to its slipcase and
   store it immediately. The disc is warm and dry after play, and will
   most benefit from being in a proper storage configuration. Under no
   circumstances leave a disc in the player for any length of time after
   play, as plastic flow may cause it to sag and develop warp.
     _________________________________________________________________
   
   
   
11. Common LD Complaints

   
   
  11.1 CAN YOU EXPLAIN SOME COMMON DEFECTS?
  
   From Bob Niland's (rjn@csn.org) LD#17: What is a "defect" on
   LaserDisc? Pink Floyd's PULSE added by Leopold.
   
   
   
    11.1.1 Crosstalk
    
   Refers generally to artifacts resulting from interference between two
   or more competing or adjacent signals. When used alone in the context
   of LD, crosstalk typically denotes the herringbone pattern (below)
   that results from the laser pickup reading, or partially reading
   signal from one or both adjacent pit track(s).
   
   This is usually a player tilt-servo adjustment problem, but is
   occasionally a mastering defect. The current LD of "Sleeper" (MGM
   ML101463, batch numbers 97-511A1 and ..B1) seems to have a mild case.
   The initial PAL release of Pink Floyd's PULSE seems to have lots of
   colour crosstalk.

    \\\\\\\\\\\\\\\\\\\\\\\\\
    /////////////////////////   <--- This is what cross-talk looks like
    \\\\\\\\\\\\\\\\\\\\\\\\\

   Other forms of crosstalk within the NTSC signal itself (and not unique
   to LD) can result in dot crawl, chroma crawl, cross-color and hanging
   dots. 
   
    11.1.2 Dropouts
    
   Loss of signal on NTSC LD (missing pits) is a form of noise that
   usually results in the visible signal going to white level at the
   corresponding point on the screen.
   
   My criteria for "defective" is a disc region with at least two
   prominent noise specks per field (CLV) or four per frame (CAV) for a
   least one minute before returning the disc. If the source material was
   noisy, I wait until the disc noise is worse than the original film
   noise. 
   
    11.1.3 Laser lock
    
   The player gets stuck on a particular frame of a CAV disc, or gets
   "lost" (on CAV or CLV). This is normally a media defect affecting only
   that particular disc. However, older or misadjusted players may
   exhibit the problem where a more recent player does not. 
   
    11.1.4 Lines
    
   Vertical and diagonal lines, whether stationary or moving, are almost
   always scratches on the film. White are on the print or interpositive.
   Black are on the interneg or camera neg. Colored lines indicate a
   scratch, in tri-pack color film or dye layer print, that didn't make
   it all the way to the film base.
   
   White lines indicate disc problems if stationary on CAV or scrolling
   on CLV. Lines lasting exactly one field are more often disc problems,
   but may indicate a film splice as well.
   
   Fixed (CAV) and scrolling (CLV) lines that are definitely media
   defects may be worth complaining about. Much of the time, these turn
   out to be debris on the disc surface that is easily removed. When
   otherwise, I tolerate no (zero) episodes per title that last longer
   than one second, and only two episodes per title that last between one
   frame and one second each. 
   
    11.1.5 Scratches
    
   Scratches on the acrylic surface of the disc may or may not be a
   problem. They are often invisible to the laser and do not result in
   video or audio errors. They are also often easily corrected, even if
   they are visible on screen. 
   
    11.1.6 Seek fail
    
   The disc plays completely in normal free-run mode, but when you
   command your player to seek to chapter, frame (CAV) or time (CLV), the
   player shuts down, gets lost, lands at the wrong place or takes an
   unusually long time to complete the operation.
   
   Although this can indicate a player problem, it can also result from
   media defects (and more rarely, mastering problems). I have several
   Technidisc pressings ("The Prisoner", episodes 1-6) with unreliable
   chapter numbers and timecodes. This is probably the result of poor
   signal quality in that portion of the vertical retrace interval that
   stores chap/frame/time. Since these IMAGE discs were subject to a
   repressing by Kuraray, I expect to exchange them at some time. 
   
    11.1.7 Skipping
    
   Player momentarily loses track of where it is, usually accompanied by
   loss of sync. Check disc for easily correctable optical obstructions,
   if none, verify on another player, then exchange it. 
   
    11.1.8 Smearing of colors
    
   Since the bandwidth of the chroma signal is less than half that of the
   luminance signal (in both NTSC and PAL), some minor mis-registration
   of colors is unavoidable. In NTSC, intense reds seem to be more
   susceptible to blooming and smearing. There are no LD media defects
   that I know of that can result only in smearing. 
   
    11.1.9 Smudges
    
   Fingerprints and scuff marks occasionally appear on factory-new media.
   They (and popcorn grease) are common on used discs. If the problem is
   severe enough on a new disc to affect the video, I clean it (article
   LD#13 available) or return it if I can't correct it. 
   
    11.1.10 Spotting
    
   Spots and blotches on the screen that are not pure white or a primary
   color, and which are larger than one video pixel, are usually on the
   original film (or antecedent elements). 
   
    11.1.11 Time compression
    
   In order to make a 123 minute movie fit on a 120 minute NTSC CLV
   platter, percentage of the 3/2 pulldowns will be shortened to 2/2
   (dropping a video field). The older cropped edition of "Star Wars"
   (CBS/Fox 1130-80) lost three minutes this way (the new 1130-84 W/S
   edition runs the full 121 minutes).
   
   If the actual video running time is listed accurately on the jacket,
   with or without an "electronically time compressed" warning, you have
   a pre-sales decision to make. If the full film running time is
   fraudulently listed, you have grounds for return.
   
   Note: PAL LDs from 24 fps film sources are routinely 4% time-
   compressed. Rather than use 12th-field-repeat, or electronic 104%
   pulldown, the common transfer process is to simply run the film at 25
   fps (PAL is 25 frames/sec, 50 fields). The only way to avoid this is
   to use a multi-standard player and import NTSC discs.
   
   More information about PAL time compression may be found at
   http://www.cs.tut.fi/~leopold/Ld/FilmToVideo/index.html#Speeds. 
   
    11.1.12 Vertical interval defects
    
   Non-displayed scan lines are used to store information critical to the
   proper operation of the LD player. In NTSC, lines 11, 16, 17 and 18
   contain, among other things, white flag, CAV stop code, CAV frame and
   CLV time. If a media defect trashes one of these signals, the player
   can fail to display a still frame, fail to auto-stop, display
   incorrect info on its front panel, fail to follow programmed sequence,
   or get lost (skip, servo-slide, shutdown). 
   
    11.1.13 Vertical interval errors
    
   The disc was mastered with incorrect data in the vertical interval.
   The most common such error results in field motion on CAV still
   frames, due to incorrect white flags. 
   
    11.1.14 Video noise, lines (usually white)
    
   Loss of signal results in white-level output on NTSC video (not sure
   about PAL). A moderate-sized point defect on an LD will often result
   in many CAV fields having the same line or lines stuck at white-level,
   or several seconds of scrolling white lines on CLV discs.
   
   Such lines are sometimes due to foreign matter on the surface of the
   disc. On new discs, tiny particles of stray acrylic (from edge
   trimming in production) scatter laser light quite effectively and can
   have a very dramatic effect on the video signal. Fortunately, a soft
   brush removes them. Such defects are almost always limited to the
   specific individual disc. 
   
    11.1.15 Video noise, snow
    
   Media defects that affect a single pit, or a small cluster of pits
   will result in either dramatic excursions of the luminance signal (too
   white) on B&W titles, or trashing of the color subcarrier, with
   resulting mis-decoding of the color at that point in the scan line.
   The visual result is white or color snow, respectively.
   
   An increase in snow over calendar time is the hallmark of Laser Rot,
   however, brand-new production can also have snow problems. Suspected
   causes of snow in freshly minted discs include: pressing discs with a
   worn or damaged stamper, pressing when the acrylic is not at the
   correct temperature, peeling the stamper and acrylic apart too soon or
   too late, metallization layer too thin, and contaminants in the
   production environment.
   
   If all the dots are white on a color program, chances are they are
   film damage and not a disc defect. NTSC noise dots tend to be random
   colors. If the dots are over one scan line high on a CLV disc, then
   they are not a disc defect, since adjacent screen pixels are not
   adjacent on CLV (they are on CAV). If the dots have vertical "tails",
   they are almost certainly print or negative damage. 
   
    11.1.16 Video noise, streaking
    
   Streaking, or frame-to-frame variation in the color of the same scan
   line (where no motion is occuring in the image) indicates noise. Due
   to the coefficients used for the primary colors, some amount of noise
   seems to be unavoidable in NTSC reds. High-end player advancements may
   minimize this in the future.
   
   However, color noise can also result from manufacturing defects in
   individual discs, and may also warn of incipient laser rot. 
   
    11.1.17 Warping
    
   The focus and positioning servos of LD players can handle quite a bit
   of vertical and radial run-out, but there is no need to accept a
   warped disc and make your player work hard.
   
   The general rule in the LD industry seems to be that a warp is a
   returnable defect if a US nickel (coin about .075 inch thick) can fit
   under the hub or outer disc edge at any point, when the disc is placed
   on a reliably flat surface.
   
   On used or rare discs, be advised that warps are often correctable.
   See the "Care & Repair" article, LD#13. 
   
  11.2 WHAT IS "LASER ROT"?
  
   From Timm Doolen
   
   The term "laser rot" is thrown around rather loosely these days.
   Oftentimes when people have a few speckles, they'll immediately think
   the disc has laser rot, but that is definitely not always the case.
   They might just have a manufacturer's defect that causes a few
   speckles. Laser rot starts out with speckles and gets worse until the
   disc is, for all purposes, unwatchable or unplayable.
   
   Probably more than half of the 120 or so discs I own have speckles
   somewhere on the disc. It's one of the things you learn to live with
   as a disc owner. But if it's to a point where it distracts me from
   watching the movie, I return it. One of the qualities of a laserdisc
   owner is that you CANNOT be bashful about returning items. I have
   returned dozens of titles over the past three years of owning a
   laserdisc player. But then again, I'm picky about quality. 
   
    11.2.1 OK, so what is laser rot?
    
   Although it is referred to as "laser rot," it has nothing to do with
   your laser and it doesn't really rot, at least not in the traditional
   sense where there is visible evidence. I suppose the word "rot" came
   from the fact that if you watch a rotting movie a lot, say once a week
   or month, the picture will get worse with each viewing, with more
   speckles and skips. One could say the picture quality was rotting away
   over time.
   
   Be warned that you probably won't see laser rot the first time you
   play a disc that eventually rots. You may not even see it the tenth
   time you play the disc. It could be months or years before the rotting
   process starts, and once it does, it can rot in a matter of weeks or
   many months.
   
   If laser rot is a real concern to you, it is a good idea to view parts
   of your discs at least once a year. But again, this is really a topic
   that is overblown, and your chances of finding a laser rotted disc is
   pretty small, with the excpetion of a few documented titles. 
   
    11.2.2 How does rot occur?
    
   If there is a possibility that air can get through the plastic coating
   of your disc, then the laserdisc can rot because of oxidation of the
   data layer. A deep scratch, an original manufacturing defect, or the
   glue heating and expanding (that's why you should store them in a
   cool, dry place) can let in oxygen. There's dozens of other
   possibilities.
   
   Because of the name "laser rot," a lot of people think they will be
   able to see the problems on the outside of the disc, but this is
   almost never the case - you have to watch the movie. Only once have I
   seen a disc that showed external signs of laser rot, and I think that
   was a manufacturer's defect of the glue getting inside the plastic. It
   looked like someone had spilled coffee and it had dried out. I touched
   it, and all I felt was the plastic coating, so it was definitely
   inside the plastic, touching the metal. There were dozens of skips on
   the disc and I of course returned it for a refund.
   
   Newcomers to the laserdisc format should not be scared off by laser
   rot It was a concern in the early to mid-80s, but most disc
   manufacturers have seemed to worked out the kinks now. Bob Niland
   estimates about 2 percent of new discs have laser rot or other serious
   manufacturing defect. In other words, almost anything made in the
   1990s should be OK.
   
   If you're really worried about it, buy from a store that has an
   unconditional return policy, or that gives lifetime guarantees. Also,
   some labels/distributors, such as Voyager, give lifetime guarantees on
   their discs. Probably most companies, if you bugged them enough, would
   replace a disc for you if the title is still in print.
   
   The truth is the defect rate is probably about the same for LD as it
   is for VHS or any other movie viewing media. But LDs start out at
   better resolution, don't wear over time, and don't have the annoying
   Macrovision copy protection coding which causes annoying VHS artifacts
   after repeated viewings.
     _________________________________________________________________
   
   
   
12. What is the pin ordering of this connector?

   
   
  12.1 SCART
  
   This connector is shown as if you were looking at the female connector
   of an LD player or VCR.

             ____
         ___/    |
        |     20 |      1. Audio OUT R          11. G IN
        | 19     |      2. Audio IN R           12. -
        |     18 |      3. Audio OUT L          13. R or Chroma GROUND
        | 17     |      4. Audio GROUND         14. IR IN
        |     16 |      5. B GROUND             15. R or Chroma IN
        | 15     |      6. Audio IN L           16. Blanking
        |     14 |      7. B IN                 17. Video GROUND
        | 13     |      8. Mode selection       18. Blanking GROUND
        |     12 |      9. G GROUND             19. Video OUT
        | 11     |     10. -                    20. Video IN
        |     10 |                              21. Screen GROUND
        |  9     |
        |      8 |     21 is the metal surrounding the connector
        |  7     |
        |      6 |
        |  5     |
        |      4 |
        |  3     |
        |      2 |
        |  1     |
        |________|21

   
   
   A more detailed view on the pins:
     * 1. Audio out R or K2; 0.5 Veff output resistance 2. Audio in R or
       K2; 0.5 Veff input resistance >=10kOhm
     * 3. Audio out L, K1 or mono; 0.5 Veff output resistance 4. Audio
       ground
     * 5. Blue ground
     * 6. Audio in L, K1 or mono; 0.5 Veff input resistance >=10kOhm
     * 7. Blue in; Max. difference 0.7V, Rl=75Ohm, DC offset 0..2V
     * 8. Switch voltage 0=TV-reception, 1=remote; 0=0..2v, 1=9.5..12V,
       input resistance >=10kOhm, input capasitance 9. Green ground
     * 10. (unused)
     * 11. Green in; Max. difference 0.7V, Rl=75Ohm, DC offset 0..2V
     * 12. (unused)
     * 13. Red or Chroma ground
     * 14. IR in; ???
     * 15. Either:
          + Red in; Max. difference 0.7V, Rl=75Ohm, DC offset 0..2V
          + Chroma in (when 20 is used as luminance in); ???
     * 16. Blanking input; 0=0..0.4V, 1=1..3V, Rl=75Ohm
     * 17. Video ground
     * 18. Blanking ground
     * 19. Video out (FBAS); Difference of Peak level and 1V signal,
       Rl=75Ohm, DC 0..2V only synchronization signal 0.3Vss
     * 20. Video or Luminance in; Difference of Peak level and 1V signal,
       Rl=75Ohm, DC 0..2V only synchronization signal 0.3Vss
     * 21. Screen ground (main ground)
       
   
   
   A simplistic working cable can be built as follows:

        Video                                           Television

        19 Video OUT --------------------------------- Video IN 20
        17 Video GROUND -------------------------- Video GROUND 17
        4  Audio GROUND -------------------------- Audio GROUND  4
        3  Audio OUT L ----------------------------- Audio IN L  6
        1  Audio OUT R ----------------------------- Audio IN R  2

   
   
    NOTICE!
    
   The fact that SCART defines a great deal of signals, like RGB and
   S-Video signal inputs, doesn't necessarily mean they are available in
   your LDP, VCR or TV set. Refer to the actual documentation of your
   hardware. Even the more expensive TVs that may have up to 3 SCARTs,
   usually have only one connector that accepts RGB, and one that accepts
   S-Video (luminance and chrominance coming through different pins). 
   
  12.2 S-VIDEO (ALSO SOMETIMES CALLED Y/C OR S-VHS)
  
   This connector is shown as if you were looking at the female connector
   of an LD player or VCR. I am not sure if the correct numbers are
   assigned to the correct pins, but they are consistent with the
   descriptions.

    ____
   /    \       1. Chrominance GROUND
  / 2  3 \      2. Chrominance
 | 1    4 |     3. Luminance
  \  ==  /      4. Luminance GROUND
   \____/5      5. Screen GROUND

   If you want to make a simple S-video -> S-video cable, you just
   connect all 5 pins as they are.
   
   To make a cable between A LDP with a S-Video connector and a TV set
   with an S-Video input with a SCART connector, the following cable
   would do the trick:

        LD Player (S-Video)                     Television (SCART)

        1 Chrominance GROUND --------------- R or Chroma GROUND 13
        2 Chrominance -------------------------- R or Chroma IN 15
        3 Luminance ---------------------------------- Video IN 20
        4 Luminance GROUND ----------------------- Video GROUND 17
        5 Screen GROUND ------------------------- Screen GROUND 21

   Of course, if you want audio to be spoiled with the lousy loudspeakers
   of your TV set, a more complex cable is required and the RCA audio
   outputs of the LDP must be routed to the SCART connector.
     _________________________________________________________________
   
   <-- Introduction Software -->
-- 
alt.video.laserdisc FAQ at http://www.cs.tut.fi/~leopold/Ld/FAQ/index.html

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