LD#17: What is a "defect" on LaserDisc? Edition: 06 Aug 92 Minor edits: 2002-07-15 I have received many inquiries of the form: "One of my disks exhibits the following behaviour. Is it defective? If so, what should I do about it?" In an effort to create a canned answer (and yet-another standard LD article) useful for responding to such queries, let me catalog the LD problems and issues that I have experienced or heard about, and indicate what I do about them. This article is not so much "What causes this defect?", but "When do I return a disc, assuming exchange or refund is possible?" and... "what standard for quality might a used disc seller & buyer rely on?" Beyond the obvious fails-to-play problems, my general measure is: A "defect" has to be: - distracting enough to notice; - remain on screen long enough to be obnoxious; - be worse than the average "good" LD, and - be worse than the average film print used for video transfers, or - actually violate IEC 857, the LaserVision standard. Personal tolerance levels will vary, and people with small TVs or TVs with response roll-off above 3MHz, will see fewer problems. It is difficult for a new LD enthusiast to know when he or she is "complaining too much" (or too little, for that matter). It is only after viewing hundreds of LDs from all vintages of production, on a revealing large-screen monitor, that one can assess what the industry was capable of, and therefore what is reasonable to demand. This article reflects my estimates. Obviously, on some rare out-of-print titles (like the VVA/ODC "Space Archive" series), the alternative to tolerating a defect might be to forego owning a copy. I have available a separate article on LD care and repair (LD#13), which gives formulas for converting the physical coordinates of a visible or audible media defect into program time and vice-versa. Before taking any action on a "defective" disc, always confirm that the problem is not in your player. Try the disc on another player. If possible, also audition another copy of the same disc release on your player. Dealer rental stock can be helpful here. If the two (or more) discs behave differently, compare mint marks and see what they reveal (a mint mark article is also available - LD#09). This article is alphabetical by problem/issue name. In some cases, there is no accepted terminology, so I have invented some and cross-referenced it. Many items listed here are NOT defects. They are listed because neophyte LD viewers, particularly those sitting too close to large screen TVs, are bothered by common LD and/or NTSC artifacts and initially assume something is "wrong". LD-101: Before passing judgement on brightness (black level), color (hue and saturation), contrast (white level or "picture"), focus and geometry (cropping, you need to ensure that your system itself is performing properly. The Reference Recordings LD-101 test disc "A Video Standard". or its successor "Video Essentials" is very useful in this regard. Since both LDs may be hard to find, you can also use the DVD "Video Essentials". Finally, let me add the caveat that I am not a television engineer. Readers who are (or who simply know more about some video topic than I do), are encouraged to send corrections and contribute more background info. I am not sure that I have included the full litany of NTSC shortcomings, and have listed only two for PAL. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Audio, mis-documented: Audio, absent: The most common instance is that the digital audio is not present even though advertised. This may be a: - merchandizing error, - a mastering defect if digital audio was indeed intended, - a manufacturing error if digital sound is present but your player can't lock on to the bit stream, or - a malfunctioning player in need of adjustment. In the case of mastering defects, the title is likely to be remastered. Complain, but expect it to be some months before exchange is possible. If the digital bit stream is missing, at least you can listen to the analog sound. If the bit stream is present ("DIGITAL Sound" indicator lights up), but the digital tracks are silent (reported on early copies of "Quiet Earth"), you cannot even select analog sound on some PAL players. Missing but documented digital sound is definitely a returnable defect. Missing analog sound (on a digital sound NTSC LD) is a mastering defect, and such discs are returnable unless the jacket advertises this unusual condition (I have only seen one such disc, and it was labelled). Audio noise, cyclic (aka helicoptering): An audio problem that is synchronized with disc rotation is almost always a media, and not a mastering problem. It usually affects the analog audio before the digital audio, and is often (but not always) accompanied by video artifacts (typically scrolling noise lines). Cyclic noise is commonly associated with laser rot, in which case it is aggravated by time. Cyclic noise is more common on CLV, and near the beginning or end of a side. Digital audio is more immune to manufacturing defects. Most errors are completely corrected by the ECC. Data values that can't be corrected are interpolated (guessed at), and if too much data is lost, the digital audio snaps to silence (mutes) or switches to analog. See also "digititis". Cyclic problems in the digital audio therefore manifest themselves as rapid dropouts, which may sound like "motorboating" which used to plague vacuum tube amps decades ago. I once received a new (1991) PVI pressing ("Day of the Jackal", MCA 11004) which had cyclic digital dropouts in the last two minutes of side 1. Curiously, the video and analog sound were defect-free (another reader reports a similar problem on another PVI disc). The replacement (same batch number 51-668A1-05) had no problems. It is possible for either or both audio channel pairs to be severely affected by problems while there is no significant problem with the video. This is because the analog FM subcarriers and the digital audio bit stream are recorded at -26dB with respect to the pulse-FM video carrier. Note: repetitive audio noise can also arise from the program source (film or tape). If the cyclic defect does not change in frequency during a CLV side, or is present equally on all sides, or starts/ends coincident with film reel changeover cues, the problem is probably not in the disc. If two copies of the disc have the same noise dots in the exact same locations, it is not a media defect. Audio distortion/pumping: There are three main sources of this problem: 1. CX auto-tripping code is present in the vertical interval, but CX noise reduction was not used during disc mastering. I would return such a disc unless it also had digital sound, in which case I might ignore the problem. 2. CX used, but mistracks. This is common when CX is used on a dual- audio program, like the first pressings of "The Graduate" (CAV), Criterion Collection CC1115L. Voyager no longer CX'es dual-audio material, but they refused to accept returns on this problem. I have a 1st-edition CC1115L and have no complaints on the commentary track (2/R). I never use the mono movie track (1/L) because the digital stereo track is superior. 3. Careless audio transfer or inferior source material. The RCA/Columbia cropped "Close Encounters" (VLD-3095) is plagued with distorted bass. There was no remedy but to wait for the Criterion edition. Audio noise, excessive: You may have a disc without auto-CX tripping (this is not a defect). Try manually engaging CX. If the noise is inconsistent throughout the disc, it may suggest either a mastering or media problem. Try another copy. If it is still consistently noisy, consider the source material. An old public-domain title from an obscure label may simply reflect the condition of the print. But if you can't even understand the dialog (my experience with United Entertainment's "A Christmas Carol", UEI-1119), send it back. Audio, reversed: Swapping of stereo channels is a mastering error and happens infrequently. The initial CAV edition of "Little Mermaid" had this problem, as well as Field Motion, and was remastered. Reversed audio may or may not routinely be remastered, but you can help make that happen by complaining. Black Bands: Consistent black bands above and below the picture are not a defect. They are the result of transfering a widescreen work to video at the original (or close to the original) theatrical aspect ratio. Black bands may be a Merchandizing Error if the LD jacket does not advise you that the video is "letterboxed", "widescreen", "matted" or "videoscoped". Note: Media defects and video master tape defects almost always result in WHITE specular or scan line effects, not black. However, see also "lines". Blemishes, optical: This is a localized departure from a flat surface in the data area of the disc. Although the laser often ignores these, they can cause laser lock, servo slide, loss of sync and/or audio digititis. I would ignore it unless there was a visible or audible problem with the program at that point. See "Care & Repair" article to calculate program time. Broken discs: One or more pieces separated from disc. Cannot be repaired. Do not buy or play. Return if possible. Even small chips beyond the end-of-program can dangerously unbalance a disc. Changeover Cues: Not a defect. Reel changeover cues are circles or elipses that appear in the upper right corner of the screen for 3 film frames at 8 seconds before end-of-reel, then again at end-of-reel. Reels run 18-to-22 minutes per, on 35mm theatrical prints. These cues were placed on the film print so that projectionist would know when to changeover from one projector to another (which was the dominant exhibition mode prior to the use of large platters with all the reels spliced together). These cues can tell you some things about the film source elements and the video transfer. Solid cues are normally punched, scratched or etched. If they are white, they were made on a print or interpositive. If they are black, they were made on the internegative, or more rarely, on the camera negative. Ring cues (not solid) are harder to interpret, since they may be dye stamped. Circular cues indicate a flat "spherical" film element. Elipitcal cues indicate an anamorphic "scope" film element (which doesn't necessarily mean anamorphic photography - it could be an anamorphic extraction from Super35, 65mm or TechniScope). You should be able to see the entire cue dot, plus some. If the cue is clipped, the transfer was cropped, panned or zoomed. Chips, outer or inner edge: On a new disc, return it. On a used disc, don't buy it if it causes vibration upon play. Chips out of the inner surfaces (data area) are more serious and may result in player damage, due to excessive focus/tracking servo excursion or possibly even a head crash. Color: Before making any assessment of color problems on a given LD, make sure that your system "knows what it's talking about". Calibrate your TV or monitor using a test LD such as LD-101 or VE (see introduction). Color, absent: Not a defect unless the jacket claims "color" and the program is not, in which case it is a merchandizing defect. The presence of color (or hand-tinted) illustrations on B&W titles may be misleading, but is very common (and color lobby cards for B&W films were very common in the B&W era). There are some titles which were filmed or taped in color, but for which the color source elements have been lost, leaving only B&W prints and kinescopes. Sometimes color prints (or three-strip monochrome color separations) turn up later and allow a restoration. Color, faded: Not an LD defect, but can be a mastering defect if the chroma level was simply set too low during the video processing. The usual cause of faded color is that the print, internegative, interpositive or camera negative employed tri-pack dye-coupler photo- chemistry, and the dyes have faded. This is all too common on source elements from the mid-50s forward, when three-strip Technicolor photography and Imbibition Technicolor prints ceased to be used. Generally, faded color cannot be satisfactorily corrected in your TV. Were it possible, it would have been done during the transfer. Rarely, you will encounter a disc with intentionally low chroma level. The 1991 widescreen (MCA 41057) re-issuse of the 1982 Badham/Langella "Dracula" is an example. Although the package does not warn you, the chroma level is deliberately about 60% of what it was on the earlier panned&scanned LD. This you can adjust to taste with your "color" control. Color, inaccurate: Not typically a defect. There are two main sources of incorrect color: 1. Attempted (and failed) color-correction of faded dye-coupler film elements. The results may or may not be less esthetic than the raw uncorrected material. Nothing else can done, although I wouldn't be surprised to see colorization applied to perform a video restoration in the near future. 2. Sloppy or idiosyncratic video transfer. Certain LD labels seem to have their own "house hue". I personally dislike the red-brown-yellow cast common on RCA/Columbia LDs. There doesn't seem to be much that can be done about it, except to complain. Color, missing in first scan line (especially on matted and letterboxed discs): If your TV has a "2 line comb filter" for removing the 3.58MHz NTSC chroma subcarrier during color decoding, it is comparing the first active picture line to a black line, and getting very confused. Chroma comb filters rely on the adjacent lines having roughly similar content, and in the case of the first picture line of a widescreen image, they don't. Color, noisy: Colorization: Electronic coloring of what was originally a B&W program may be a crime, but it's not a defect, unless the jacket fails to warn you, in which case it is a mechandizing defect. Incidentally, colorization is done in the digital video domain. The original film or analog video tape is untouched. Colorized titles are rare on LD, and are usually available in unretouched form as well. Turning down the color on your TV or monitor may, or may not, restore the original B&W image. Content errors: One or more sides of the discs have program material totally different from that listed on the jacket. That is, the discs are obviously from some other title. This is usually a manufacturing and/or packaging error and is definitely returnable. If the disc is a collection of short works, and more or less are present than advertised, I return it if, had I known before hand, I would not have bought it in the first place. Contrast, excessive or soft: This is typically not a defect (and this discussion assumes that the white and black levels of your system are correctly calibrated, using LD-101 or VE for example). Film as an image recording medium has more latitude than video, about 7 stops, compared to 5.5 for video. Unless a modern telecine (such as a Rank) is used for the video transfer, a low-contrast "TV gamma" print/negative must be struck. In the early days of LD, this was often not done, and many DiscoVision titles (and MCA re-releases from the same video masters) are overly bright. Grading ("timing") errors sometimes still sneak through today. One shot at 12:20, side 1, CBS/Fox 1011-80 "The Day the Earth Stood Still" has a timing problem. Complain, but these sorts of problems will generally not result in a re-mastering. Cracks: On a new disc, return it; period. Don't even attempt to play it. On a used/rare disc, consider using my repair techniques before playing. Small radial cracks at the outer edge (usually from rental rash) may not be a serious problem, but warrant an effort to prevent propagation. Crawl: Lines of dots moving vertically or horizontally along the edges of objects in the frame. Dot crawl and chroma crawl are artifacts resulting from color sub-carrier phase progression, cross-talk and other limitations and compromises of the video standard, and are not LD defects. Investing in an LD player or monitor with a multi-line comb filter and perhaps a line-doubler may reduce them. They are most evident at viewing distances of less than four screen-heights. You can reduce them by turning on your TV's notch filter (if any) or moving your seating position back, generally eliminating them at eight screen- heights. Crawl problems are more apparent on NTSC color than on B&W and PAL, and arise from the fact that the color subcarrier frequency (3.58 MHz) is an odd multiple of 1/2 the line rate (chosen to minimize dots and crawl). This results in an alternation of the subcarrier phase by 180 degrees on each suceeding line. Any color decoding errors have opposite results on each line, and on a still image require 4 fields (2 frames) to repeat. During the 4-field cycle, the resulting artifacts appear to move, the direction and speed depending in part on your own eye motion. Cropping: Before concluding that there is a problem, see "Geometry". Cropping is the loss of original image content at the edges of the screen. Cropping takes two major forms: Panning&Scanning: The loss of left/right edge material from a widescreen original. If the aspect ratio of the source material is greater than 1.33:1 (4:3), the image cannot be transferred to video at full height without losing something from one or both sides. This is not a defect, and is only rarely mentioned on the jacket. To avoid objectionable cropping, you need to read responsible LD reviews, or research the film to discover if it was filmed in a "hard" widescreen process (like Cinemascope). The remedy for P&S cropping was to wait for a widescreen ("letterboxed") LD edition. Zooming: If the source material was 1.33:1 full-frame, some edge material may be lost if the transfer operator zooms in and only scans the "TV safe action", or worse, the "TV safe title" area of the original. If part of the start or end title sequence is cropped, this has happened. Complain, but it is not considered a defect by the industry. Zooming also happens on some films that were composed for widescreen, but photographed "soft-matte" on full frame. The zooming may result from an attempt to fill the video screen from the composition rather than from the camera image, especially if the upper and lower regions were not completely "protected for TV" or have absent special effects. Cross-color: Overlapping color and uneven vertical edges between objects of different colors. Not a defect, this results from various limitations of NTSC, and is often worst when the two colors are "maximum phase change" apart, for example magenta and green. Cross-talk: 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 LD of "Sleeper" (MGM ML101463, batch numbers 97-511A1 and ..B1) seems to have a mild case. \\\\\\\\\\\\\\\\\\\\\\\\\ ///////////////////////// \\\\\\\\\\\\\\\\\\\\\\\\\ 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. Cut-out (aka punchout): The LD jacket or box has a hole in one corner or a nick in the edge near a corner. This is not a defect, unless the punch or drill damaged the disc(s) within. The liner may have to be replaced in any case. When a disc title is overstocked at the distributor, or when it is deleted from the catalog with stock remaining, the excess/remaining stock may be defaced in some way and sold to the retailers at a larger than normal wholesale discount. The defacement distinguishes cutouts from ordinary stock. Retailers cannot return cutouts for credit as they can on ordinary slow-moving stock. Cutouts can be returned if defective. Such warehouse-cleaning usually involves multiple titles, and is often the occasion for special sales at the retail level. I would not expect to pay list price, and would expect to get a greater-than-normal discount on a cutout. Cutouts often provide an opportunity to acquire titles passed up at normal prices. Sometimes a title would appear as a cutout due to impending re-issue in an improved edition (widescreen, digital sound, restored length, etc.). I'd expect all unsold "new" LD inventory in North America to now be considered "cut outs". Digititis, audio: This is any of several audio problems unique to digital audio. I have experienced only cyclic dropouts on LD yet so far, but others are common on CD, and may be expected to appear eventually on LD. They include: loud ticks, drop outs (muting) and muddy sound (gross interpolation). I return disks with any of these problems. There are other CD defects which would be accompanied by video problems, these are not included in this paragraph. Dropout behaviour may vary dramatically between player brands and models. Some may drop back to analog audio on uncorrectable digital audio errors. Others may mute and only fall back to analog on loss of digital bit stream "carrier". Digititis, video: Although LD video is analog, new titles are often mastered from D-1 or D-2 digital video transfers. When video defects occur that exceed the error correction and concealment strategies of digital videotape, novel artifacts are visible. "The Sea Hawk", MGM ML101855 (1991 re-issue, batch number 51-264A1-07) has a number of digital video glitches. The most extreme is at 7:50 into side 1. The signal apparently has a problem that becomes uncorrectable at some point, and a repeating-line concealment followed by a total breakdown into random luminance and chroma values appears briefly in several fields. Dot Crawl: see "Crawl" (or the lower video framelines of daytime CNN Headline News). Not a defect. 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. The only vendor data I have seen for this is for ODC's RLV write-once media, for which they specify a dropout rate of "<1 per frame average", which is 1/4 of my standard for a defect. Errors, generally: An error is a mastering or packaging defect, and will be present in all copies of that title/edition from that master. I sometimes elected to keep an error until a new transfer or a re-mastering was done (as I did in 1991 with the Criterion CAV "Close Encounters"). Failure to play: I confirm the behavior on another player and then return the disc. My experience with this problem has been limited to severely rotted antique DiscoVision pressings and one side of a recent 3M disc. ("Casablanca, CAV Criterion CC179L, side 4. The replacement, same 3M batch number 20912A, did not have the problem.) In 1989..1991, Technidisc pressed some discs for IMAGE that reportedly have an incorrect value for the PAL-vs-NTSC lead-in code. These discs are unplayable on early production Pioneer CLD-990 , -1090, -2090 and -3090 players (and possibly some late multi-standard players as well, but NOT the CLD-M90). There was an exchange program for the titles (expired now) and a player modification was available. Field Motion: Significant image movement during a CAV still frame. Compare with "interlace twitter". Field motion may be a mastering defect, but as often is not. It is a defect when it results from the two video fields (one video frame, and a single CAV rotation) being drawn from different source film frames. If the source material is 24 frame/second film, and field motion is evident in 3 of every 5 frames (or more rarely in every other frame, or in every frame) for a significant portion of the program, then somebody goofed the "3/2 pulldown". On CAV "collectors editions" this is inexcusable, as it destroys the purpose of having CAV. If the source material is original live (not animated) video, field motion is unavoidable, as the image is changing between all fields. If the source material is odd-speed film (e.g. 21 fps silent), field motion may be unavoidable. Field motion can also occur during segments of otherwise stable 24 fps film transfers, if the video master was edited after the film transfer. Depending on the edit point, the field dominance may have changed, and gone unnoticed (example: Criterion CAV "2001" in two sequences). I have a separate article available on the mysteries of CAV still and 3/2 pulldown (LD#12). Film Damage: There are any number of problems that can aflict the source motion picture elements used for the video transfer. Amoung these are scratches, splices, spotting, emulsion flaking, mis-registrations, audio noise/distortion/dropouts, faded and/or contrasty image, film weave. If the resulting disc is so unpleasant that I won't want to watch it, and the jacket did not warn about the rough condition of the materials, I would return it. Flickering: See "interlace twitter". Any other kind of artifact usually called flickering may be the result of variation in the film or video source (especially on very old filmstock, kinescopes, other film photography of raw video screens and sloppy standards coversion). If you sit closer than one picture height, NTSC will visibly flicker. Move back or buy a scaler (line doubler or quadrupler). Focus, soft: This can result from any number of factors: 1. Standards conversion. Transfering PAL to NTSC (or vice-versa, or worse, round-trip) always results in a soft image because line- and time-interpolation is being done each pass. It can also result in judder. The Criterion "39 Steps" (CC1103L) was reportedly mastered from a PAL video tape and there were complaints about the image. 2. Poor source elements. The 13th-generation bootleg print from which the LD was made may be the best available material. LDs of public domain titles are sometimes made from beat-up prints of dubious heritage, such as 16mm, bootlegs and TV syndication. On old titles, pay attention to who is credited on the jacket. If the original studio is not, you may be buying a junker. TV-sourced material recorded on early videotape also has limitations. A recent example is the 1960 Mary Martin "Peter Pan" (Image ID7910GT), which existed only on quadraplex VTR reels. We are lucky to have had it on LD at all. 3. Kinescopes. Material that originated on TV, particularly live programming from the pre-videotape days, may have been preserved only by filming the video image on a broadcast monitor. The resolution and contrast will be limited, and the line structure won't exactly match your TV's, and so may exhibit artifacts. 4. Soft transfer. The original photography, or the video transfer may have been deliberately softened for artsy-fartsey reasons, or it might just be a screw-up. Example: "The Deceivers" Warner 767, batch numbers 50-341A1/B1. Geometry: Before concluding that there is a problem, make sure that your TV/monitor is adjusted for minimum overscan and correct geometry. LD-101 or the safe-title color bars on CAV Criterion discs are useful. A service call is required on most sets. Do not poke around yourself unless you know what you are doing and have the service manual and appropriate tools. TVs contain lethal voltages, and unskilled adjustments can calibrate you and/or your set beyond repair. On a correctly adjusted system, LD geometry problems are supplied in two major flavors, see: Cropping and Squeezing. Glue, excess: Sticky edges are not a defect, and they may remain sticky indefinitely. Glue is more evident on 3M production than on other vendors. I ignore the glue, but would trim obnoxious amounts off with an Xacto knife. See the "care & repair" article for tips on removing the glue from playing surfaces (where it can result in video artifacts). Helicoptering: Image Breakup: Inclusions: any foreign matter embedded in or below the acrylic surface or in the data layer. These usually result in scrolling video noise lines on CLV, and stable white speckles or lines on CAV. Inclusions are supposed to be impossible, since LDs are made in a clean room environment, but I have seen one case of a sand-size particle ("Manhattan", MGM ML100469). Such defects are limited to the individual disc specimen. Return it. Hanging dots: Not a defect. This is another artifact of NTSC limitations. The horizontal line between two areas of different colors is straddled by a comb-like pattern that is one or two scan lines high. Two-line comb filters exaggerate it, and chroma notch filters can pretty much eliminate it. It seems to be most severe when the colors are 180 degrees apart in chroma phase. Check the green vs magenta areas on any NTSC color bar pattern. Herringbone: Interlace twitter: Not a defect. This is a result of using two interlaced video fields to create a single video frame. It can be mitigated to some extent by sitting further than 4 picture-heights from the screen, or spending money: using an IDTV, or external line doubler and non- interlaced RGB display. Background: In the case of NTSC, the screen is refreshed at 59.97 Hz, or approximately 60 Hz. |<-----------------1/30 Sec.----------------->| |<-------------------FRAME------------------->| Apparent FRAME |<--------FIELD------->|<-------FIELD-------->| ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### ##################### Time = N Time = N + 1/60 sec. The 60 Hz FIELD rate actually generates a 30 Hz FRAME rate. Because of the phosphors used in the TV display, and persistence of vision in the human eye, the first field has not completely faded before the next one arrives. Thus we see a complete frame, usually, most of the time, sort of... Objects consisting of single horizontal lines flash on and off at 30 Hz. Thicker objects have their top and bottom edges flash on and off, often appearing to jump up and down at 30 Hz. Jaggies: Jitters, horizontal: There are two principal sources of horizontal instability, only the second of which might suggest a transfer defect. 1. Film weave: the typical 35mm film frame is held in place by four sprocket holes on either side. If the camera, printer or telecine sprockets were worn or loose, registration errors can occur and/or accumulate. Short of manually aligning each image in a frame-by- frame reprint, nothing can be done about it except to ask the disc producers to seek out better source material. "The Brave Little Toaster", Disney 1117AS, has a moderate case of film weave. 2. Time Base Errors: The individual video scan lines are not properly aligned with each other as they enter the TV/monitor. If you have a VCR, you are probably familiar with line-to-line horizontal jitter, since the majority of consumer VCRs don't have time base correctors. All LD players have TBCs, and all video transfer paths presumably included a TBC. You should not see VHS-magnitude time-base errors on LD. If you do, it may indicate a player problem. If it affects only one disc, it indicates a sloppy transfer, probably from consumer video sources. Jitters, vertical: Can be a vertical hold problem in your TV/monitor. It is also possible for the original film source elements to have a registration problem. There is a reported bug in the Pioneer CLD-3080 player that results in infrequent but repeatable vertical jitter on some CLV discs. A hardware fix was supposed to be available, but I have no further information on it. Judder: Jerkiness when objects move horizontally across the screen (and to a lesser extent vertically). Judder results from periodic original film frames (or video fields/frames) being repeated for too many LD video fields. This is usually the result of a sloppy "pull-down" transfer of film to video, however, the skilled observer can detect the judder even from a correct 3/2 pulldown. Judder can be eliminated altogether by using electronic pulldown of one film frame onto a literal 2.5 video fields, but this technology has only just become available. Recent UK and Australian TV shows based on old US newsreel and documentary footage may have a severe problem with judder. It appears that some of the 24 fps film was transferred to NTSC by 4th-frame repeat (instead of 3/2 pulldown), then standards-converted to PAL, then standards-converted back to NTSC. Some of the film may also have been 18 fps, which could aggravate the problem further. Had early Discovery "Wings" shows ever showed up on LD, we could have expected judder. Silent films pose a particular problem to transfer satisfactorily because even at their nominal 18 fps rate, all motion looks jerky. When transfered to video at 3 fields/frame, plus 4 fields on every third frame, that third frame (two video frames) may be quite noticeable. 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. I have a CLV title that has an unplayable spot on the ~1981 Pioneer VP-1000, but plays perfectly on every other player I have tried. Laser Lock is relatively rare (well under 1% of titles, in my experience), but does make a case for having an understanding with your seller on just what constitutes a "defect", and how the seller will verify it. On the other hand, if you have an antique analog-only gas-tube laser player, it is well past time to upgrade. Laser Rot: This is a definite media defect and is the most infamous of LD defects. Laser rot is the appearance of, or an increase in video (and perhaps audio) noise over time, on a disc that did not previously exhibit the problem. The noise is usually snow, and may be color or B&W. Streaking may appear as entire scan lines degenerate. On older media, there may be visible wavy variations in the diffraction patterns of the data layer. Rot has been postulated to have many causes, the most popular being oxidation of the data layer from within the disc. Although colloquially called "laser rot", the phenomenon has nothing to do with the laser or even how many times the disc has been played. Theoretically, you can minimize your chances of rot by proper storage (I have an article on the topic, LD#13). Rot can develop in weeks, months or years, and can affect the media from any manufacturer (although 3M is less affected than others). Based on my experience to date, you can expect 2% of your newly manufactured discs to turn sour in time. If you buy used discs, the DOA rate from rot can be as high as 30% (but most pre-1987 discs that are going to rot have already done so), and the same might be said for any pre-2000 production. My criteria for emerged "defect" is the same as for Dropouts; 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. Note on new discs and first noise observations: If the noise does not appear in the matting or letterbox bands on a widescreen disc, or starts/stops abruptly at reel changes, then the problem may be spotting, flaking or other damage in the source material, and not on the disc. Letterboxing: Not a defect. Letterboxing is characterized by black bands above and below the video image. There is is no picture there because there was nothing there in the original film, which was filmed in a widescreen process that had a "hard" aspect ratio greater than 1.33:1. May be a merchandizing error if not documented on the jacket. Some matted LDs are mis-labelled "letterboxed", a result of lack of a precise video industry definition for these terms. 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. Non-white horizontal lines are usually film damage. IMAX (15-70), VistaVision (8-35) and Technirama (anamorphic 8-35) can have horizontal scratches. 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. 70% 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. The Pioneer CLD-3090 is reported to exhibit black horizontal lines in response to some types of minor media defects that would cause white or bright colored dots on other players. As of 03/92, no complete fix had been reported for this behaviour. Loss of sync: A one-frame roll after a completely white video frame (e.g. a flash or explosion) typically suggests a misadjustment in your TV, monitor or projector. A side that has active picture in the first LD frame may also trigger a one-frame roll on sensitive displays. Loss of sync on normal picture suggests a trashed vertical interval and/or frame at that point, caused by a localized media defect. Verify on another player. Mastering Defects: The disc does not perform as documented due to errors during mastering (or pre-mastering: during film-video transfer). All copies of the disc from the same batch will have the problem. When the problem prevents my intended use of the disc, back it goes. The most common mastering defect is CAV Field Motion on 24fps film-source material, resulting from incorrect white flags. The most notorious recent non-white-flag problem was probably the initial pressing of the Criterion CAV "Close Encounters", CC1241L. Chapter marks are incorrectly placed and some stop codes are missing on sides 1,2&3 (batch numbers 51-330A1 thru 51-330C1). The [mostly] corrected re-mastered sides are batch numbers -330A2 thru -330C2. Boxed sets should be re-mastered pressings. Open and inspect any tri-fold sets, since Voyager didn't change the Edition date on the jackets. Matting: Not a defect. Matting is characterized by black bands above and below the video image. There is is no picture there because you are seeing the full widescreen theatrical width (or nearly so). You are not seeing the full camera aperture height for any of the following reasons: * That portion of the image was not shown in theatres, and the director/producer doesn't want you to see it at home either. * That area of the camera neg was not "protected" and contains staging, equipment or other distractions not intended for viewing. * That area of the final film was not included in the special effects that were added to the widescreen (sub-frame) image. May be a merchandizing error if not documented on the jacket. Matting or over-matting can also be a transfer error, as in the case of Ridley Scott's "Black Rain", which was filmed in Super 35 and matted to 2.35:1, but was reportedly supposed to have been matted to 1.85:1. The widescreen discs were widely available as cutouts shortly after release. Paramount never fixed it, so take your pick between a vertically cropped "widescreen" LD or a horizontally cropped "pan&scan" LD. Merchandizing Errors: If you have been reading along and taking notes, by this point we have a litany of candidates for this category, running from trivia like failing to print a CX logo all the way up to outright fraud. Examples include: listed chapters not encoded, fake stereo without disclaimer, time compression or incorrect running time generally, censored or edited for TV, mono sound (and not supposed to be), digital sound absent (but claimed), matted or letterboxed without warning, subtitles vs dubbing (on foreign films), colorization (without warning), B&W (on a color film), etc. If the problem is serious enough that I think the product will be remastered, if not recalled, I wait and exchange it. Otherwise, the rule I use is: Had the product been correctly labelled, would I have bought it despite the deficiency? If so, I keep it. If not, I demand a refund. For example, I have an LD of cartoons which lists chapter marks, but has none. Had it not listed any chapters, I would have bought it anyway. (It has 1-second CLV timecode resolution, so I can seek to each 'toon with little difficulty.) Moire patterns: Not a defect. These are moving or stable geometric images that are clearly not part of the original scene. They are most apparent on images containing fine repeating detail (e.g. window blinds) and are not generally an LD defect. They are usually sampling errors resulting from trying to depict objects near the resolution limit of video (or near the phosphor dot pitch of your direct-view TV tube). In widescreen NTSC editions of "Blade Runner", all of the scenes in Deckard's apartment that show window blinds have this all-too-common problem. Solution? Wait for HDTV. Even DVD couldn't completely avoid this. Overscanning: Pixelation: A single point on a scan line, or a group of points that are stuck at a single luminance and/or chrominance value for several frames, while the surrounding image changes. A physical point defect on a CAV LD will usually result in a pixel stuck at white for a few seconds. Pixels stuck on CLV sides, or at other than white-level, suggest a defective LCD panel in your projector, a stuck bit/byte in the digital field/frame stage of your player/TV/monitor or a stuck bit/byte in the D-1 or D-2 recorder or digital editing suite used to master the disc. The W/S re-release of "LadyHawke" (WB 12370) seems to have a couple of stick pixels on the last CLV side (batch 52-517C1-01). Pull-down errors: Punch-Out: Rolling: Running Time: There can be a number of problems associated with the total running time of an LD title. Before you complain about a time inconsistency, you need to have a reliable reference work handy. I use Halliwell's Film Guide and Maltin's TV Movies Video Guide. These are not infallible, and sometimes disagree with each other (since Halliwell is based on UK running times), but they are a place to start. I kept a file of titles that I was interested in, and one of the entries was expected running time. * Jacket errors: The actual running time of the program does not match what is advertised on the jacket. This is grounds for return if the actual time is shorter than reference times. Act based on whether or not you would still have bought the title had you known about the timing beforehand. Example: "The Devil and Daniel Webster", Embassy 60515, claims 109 minutes but is actually 84 (as were all versions until Voyager/Criterion discovered 20 missing minutes in late 1991). * Seriously short time: LDs made from public domain prints, or from late theatrical prints may have material missing due to splices or deliberate editing to reduce time for theatre scheduling or broadcast purposes. This is generally not a returnable error unless the jacket advertises a longer time. Unless there are alternate editions of the title (e.g. on Criterion), your choice may be a short show vs foregoing the title. * Missing minute: I normally don't pay too much attention to variances of a minute or so from reference times, unless the program originally ran between 118 and 123 minutes. Missing time on such programs suggests triming to make the work fit on one NTSC CLV platter (two sides). See also: Time Compression * Excess time: the actual screening time exceeds expectations. This is infrequent and is not a problem unless the additions are significant and not advertised as a "restored" or "special edition". Often there are sound esthetic reasons why the material was omitted from the theatrical release. 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. I have never had a new disc with scratches. If I received one, whether or not to return it would be a matter of visibility and ease of correction. On a used disc, I always inspect for rental rash before purchase anyway, so the issue of returns would only arise if I decided I could correct the problem, but was unable to. This hasn't happened yet. 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, avoid the TD pressings (or get the DVDs of that series). Servo Slide: The play speeds up or enters forward scan mode up without having been commanded. Normal speed may or may not resume. I have seen one CAV side with this problem ("Andromeda Strain", MCA 13001, side 3), and after examining the side to see if there was correctable optical obstruction, and finding none, I exchanged the title. The replacement (same batch number, 51-431C1-08) did not have the problem. Probably a case of trashed vertical interval codes. Side Swap: The labels and the data don't match, but both sides are otherwise present and correct. You may disagree, but this manufacturing defect is not generally considered to be grounds for return and exchange. I do not recommend attempting to remove and swap the labels, or adding new labels. You can screw up disc clamping in your player, and the [re]applied labels may cause excessive vertical runout or come loose during braking. On the other hand, if a side's data is missing (or duplicated - and this happened to me with "You Can't Get There From Here", Voyager VP1011L, a PDO/UK pressing), or is out of sequence across platters (and therefore unplayable in correct auto-change sequence without manual intervention), return it. Replacement copies, even with the same batch numbers, rarely have the same problem. 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. 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. Low frequency video noise results in line-to-line variations in chroma and luminance that looks much like smearing. I have only seen this once (side 1, "Eames Vol.1", Voyager V1045L, batch 52-136A1-07). The replacemet had the same problem, suggesting a video master problem. As more and more documentary and news footage is gathered on VHS, VHS-C, S-VHS, 8mm and Hi-8, we could expect to see 1990s LDs made from this material and exhibiting the limitations of these consumer formats. 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. On used discs, I routinely clean them and replace the sleeves anyway. I return only if problems are uncorrectable. Snow: Soft Focus: Speckles: Splices: 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). Staircasing: Narrow diagonal lines, typically near horizontal, are not straight, but appear to be made of several stepped line segments. Not a defect. This is a limitation of the resolution of your video standard. Standards Conversion: Not generally a defect. The process of converting between PAL (626 line 50 field/second) and M/NTSC (525 line 60 field/second) requires both spatial and temporal interpolation. Some converters attempt to minimize judder by estimating motion and trying to predict where to interpolate. When this fails, the result can be single fields or sequences of fields with visible image fragments following moving objects. Many people noticed such problems in the NTSC broadcasts of the 1992 Summer Olympics, which were shot in PAL. When such programming is available on LD, expect to see these artifacts. Streaking: 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 newer 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. I have one report of a 121 minute movie ("Remo Williams", HBO TVL3676), apparently time-compressed, that contains cyclic field duplication (both LD fields identical, and the complementary field missing). This is a pre-mastering error. I would return it if I could notice it. 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. Venetian Blind (aka "Hanover Bars") - A vertical line crawling pattern unique to PAL, and a result of the way that PAL misbehaves in the presence of chroma phase errors. Not generally a mastering or media defect. 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). When a vertical interval defect interferes with my intended uses of the disc, back it goes. Failure to stop at even one stop-code is a returnable defect in my book, as is failure to seek to even one still- frame of an interactive CAV title. 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. See Field Motion. Other errors are much more rare. The Criterion CAV "Ghostbusters" (CC1181L) has two chapters with the same number. Fortunately, they are on different sides, and even in multi-sided programmed play, contemporary players don't object - otherwise I might have returned it (I did write a letter to Voyager about issues with that title). Vertical Roll (sync loss): Vibration, Excessive: Since manufacturing tolerance are far greater than the track pitch on an LD, some amount of vibration is inevitable, as the laser head seeks back and forth once per revolution to stay on track, and up and down to stay in focus. I define "excessive" vibration (when confirmed on a second player) to mean any of... * Disc fails to play at any spot, or any expected play mode fails, such as reverse play on CAV (or CLV via digital field store). * Player physically "walks" (moves). * Visible cross-talk or other artifacts on screen. * Seek times exceed twice "normal" for similar access on another disc. * Mechanical vibration noise is distractingly loud on two or more players (this will require some experience to gauge). Vibration can be caused by excessive horizontal run-out (severe concentric mis-alignment of the data track with the center hole), mis-alignment of the two glued sides, non-concentric trimming of the outer edge or inconsistent thickness of the acrylic across the diameter of the disc. Video Noise, cross-talk: 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. If the defect cannot be corrected, return the disc (as I have, several times). Such defects are almost always limited to the specific individual disc. 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 (more common back in the DiscoVision days). If all the dots are white on a color program, chance 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. 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. However, color noise can also result from manufacturing defects in individual discs, and may also warn of incipient laser rot. Try another copy of the same disc. Warp: 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 IEC LV standard requires a maximum static deflection of -2.5mm (about 1/10 inch). If you set the disc on a small flat object 2.5mm thick, on a flat surface, no part of the disc edge should touch the flat surface. 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. Apart from that test, any warp which causes your player to mistrack, or vibrate noisily, is a returnable defect in my opinion. On used or rare discs, be advised that warps are often correctable. See the "Care & Repair" article, LD#13. White Flags: White Lines (stationary): On CAV, usually due to the same cause as Pixelation, except that the physical defect is larger, covering one or more entire line periods. On CLV, and the lines aren't scrolling, it is a mastering defect. Windowboxing: is the horizontal variant of letterboxing, and is not a defect. There are black vertical areas at the side of the image. If you haven't seen this process, the daytime CNN Headline News broadcast is sometimes windowboxed when the stock ticker is displayed. On LD, you can expect to see windowboxing in several situations: 1. The producer/director desires to compensate for the overscanning of typical TV sets and had the video transfer performed at less than full video width. The opening title sequence of Criterion's "Yojimbo" (TohoScope) is windowboxed. 2. 1.3:1 works where the video producer desires to have subtitles out-of-picture. 3. Early silent movies shot at less than 1.33:1 aspect ratio, and transferred at full height. Zooming: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Copyright 1991, 1992 Robert J. 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Regards, PO Box 248 Bob Niland Enterprise mailto:name@isp-name.domain Kansas which, due to spam, is: 67441-0248 USA rjn AT access DASH one DOT com Unless otherwise specifically stated expressing personal opinions and NOT speaking for any employer, client or Internet Service Provider.