Introduction To LaserDisc

Contents

About the LaserDisc format

LaserDisc is a replay only video disc system based upon the same laser-read optical disc technology used by the Compact Disc digital audio format. LaserDisc is the sole survivor of the video disc format wars of the early 1980s, and has become firmly established as THE domestic Video Disc system. LaserDisc as it is now known (it has previously been known as LaserVision, DiscoVision, and CD-Video) was originally developed by the Dutch electronics company Philips in the 1970s. Philips found a Japanese ally in Pioneer who have provided may innovations of their own, most notably the now ubiquitous combi player first released in 1984.

LaserDisc has achieved its considerable and growing success for one major reason - the quality of its reproduction of picture and sound. LaserDisc can deliver images and sound with a clarity and precision unmatched outside of a broadcast Television studio. While all domestic video tape systems, including the High Band formats such as SuperVHS and Hi-8, modify the recorded image to reduce it's signal bandwidth, LaserDisc does not. In fact, it is not until you reach video tape formats such as 1" C format or D-2 that video tape recording systems can match the video and audio performance of LaserDisc. Those systems cost upwards of fifty times the UK#600 cost of a mid range LaserDisc player. It is the ability of LaserDisc to deliver better than broadcast quality pictures and sound that has made it the format of choice for videophile and home cinema systems the world over.

In addition to the quality issues, LaserDisc also benefits from its close association with Compact Disc. LaserDiscs released now all carry a Digital Audio soundtrack which uses exactly the same 44.1KHz 16bit signal standard used by Compact Discs. The majority of players still support playing the analogue soundtracks of older discs typically dating from 1978 through to about 1986. Almost all LaserDisc players, known as combi players, can also play the conventional audio-only Compact Discs. LaserDisc combi players don't just play Compact Discs, they play them exceedingly well, often matching the performance of similarly priced dedicated Compact Disc players. Part of this is due to the effort that is put into making the performance of the audio side as good as possible, but that is not the whole story. The large disc clamp needed to hold the 300gm weight of the 30cm LaserDisc adds a lot of additional stability to the smaller 12cm Compact Disc while playing. In addition, the faster response and greater degree of movement in the laser pickup head, give the LaserDisc player a distinct advantage in tracking warped and damaged Compact Discs.

LaserDisc also shares the convience features of Compact Disc, such as track numbers (known as Chapters in LaserDisc nomenclature), real time counters and rapid random access. The LaserDisc player provides Next and Previous chapter buttons, direct access to any chapter on the side by chapter number, and can also go directly to a specific time on the side. The connection from the LaserDisc player to the video monitor is used to good effect when playing Compact Discs since the many different pieces of time information (total elapsed, total remaining, track elapsed, track remaining) can all be displayed.

LaserDisc in the PAL market

By comparison with North America and Japan, the market for LaserDisc in PAL territories is still small. Since LaserDisc does store a complete video signal, it does suffer from subdivision into two seperate formats; that based upon the 525 line 30 frame per second NTSC (EIA) video system and that based upon the 625 line 25 frame per second PAL (CCIR) video system. Fortunately the further sub-division of the 625 line (CCIR) based systems into the PAL and SECAM colour systems was avoided. The colour information is always recorded on the disc in the PAL colour system, and players for SECAM markets perform an internal transcode into SECAM.

In many South-East Asian countries, NTSC LaserDisc is the norm despite the local television broadcasts being in PAL. In Europe and Australiasia however domestic LaserDisc releases do happen in the PAL colour system. Unfortunately, due to the smaller size of the market, language barriers, and doubtfull marketing decisions in the past, the market for PAL LaserDisc is not very well developed. Even the UK which has the currently most active PAL LaserDisc catalogue at around 1,000 titles pales into insigificance beside the 8,000 or so titles available in the USA, and the 10,000+ available in Japan.

This significant deficency has actually improved matters, since it has encouraged the LaserDisc player manufacturers to concentrate on producing dual standard players. When used in conjunction with multi-standard televisions or video monitors, these players produce results on a par with single standard players. Small compromises do come into play when the players are required to reproduce NTSC video material on a PAL-only TV, a feat which all dual standard players can achieve with almost any reasonably modern PAL-only TV. All current dual-standard LD players can offer the ability to switch between a pure NTSC output and a modified output suitable for use with a PAL-only TV. There are two techniques employed to play an NTSC LaserDisc on a PAL-only TV; the first involves making a hyrid signal consisting of the EIA (NTSC) monochrome information mixed with a PAL encoded colour signal, the other involves decoding the NTSC signal into seperate RGB signals and feeding these to the RGB input pins on the TV's SCART socket. The transcoding approach (pseudo-PAL) is used on Pioneers CLD series machines, and works with a very wide range of TVs, but suffers from some loss of colour information thus making the colour levels a little low. The decoding approach (SCART RGB) works better from a quality viewpoint but requires the presence of an RGB wired SCART socket on the TV. While most TVs with SCART do have this, some of the very cheapest or older sets do not. The decoding approach is used by Sony and Philips in their players.

There is a seperate document within this web server which details the current offerings from player manufacturers.

Overview of LaserDisc software

Since LaserDisc is a replay only system, the quality and availability of software for the system is of paramount importance. As discussed above, the PAL market is in a way fortunate to have been driven into a situation where dual standard equipment is the norm, since this means that the range of software usuable on these players encompases all of the material available around the world. While the NTSC colour system has received a bad press for it's poor quality, it should be emphasized that the much publicised problems with inaccurate colour do not extend to the NTSC LaserDisc format. The differences that do exist between PAL and NTSC LaserDiscs are minor and the two should be considered as directly comparable. Both have their own positive and negative features which should be evaluated on a per case basis, but more on that later.

For a while, some PAL LaserDisc distributors attempted to duplicate the American catalogue by releasing titles that were already available in the USA. This met with very limited success in that the majority of potential purchasers had already purchased the NTSC version. Instead, the effort is now being concentrated on making the PAL version a simultaneous release with the US NTSC disc with additional features and/or at a lower price. A couple of specialist labels have also been concentrating on releasing material on PAL LaserDisc that is not yet available in NTSC. These policies have produced some favourable comparisons with the NTSC releases.

For example, Guild Home Video/LDCE's release of Terminator 2: Judgment Day included the trailers and Making of documentaries only included in the $99 NTSC special edition, but at a price of UK$34.99 (US$50). Columbia Tristar's release of Bram Stoker's Dracula was similar, again offering material only available in the expensive US special edition. Guild Home Video/LDCE also achieved similar success with their letterboxed release of the four hour version of Dances With Wolves. The four hour version is still not available on NTSC LD. Columbia Tristar scored a considerable success in January 1994 with the release of Last Action Hero, some 3 weeks before it's US release and at UK#29.99 (effectively) considerably cheaper than the US letterboxed release at US$44.99.

The recent activity in the PAL market has shown that a lot of lessons have been learnt from the US market, most notably the prevalance of the letterboxed versions of widescreen films. PAL releases have also benefited from extensive chapter marks, supplimental material, and use of active play mode on third sides. Late in 1994, Pioneer LCDE also scored a first releasing a widescreen LaserDisc of Jurassic Park in both PAL CLV and PAL CAV versions.

In the US market, there have always been two major distributors for LaserDisc who handle the majority of the titles released, these are Pioneer's LaserDisc Corportation of America (LDCA) and the independant Image Entertainment. In the European marketplace, Pioneer are once again present in force in the form of LaserDisc Corporation of Europe (LDCE), and Sony through Columbia Tristar. Pioneer's LDCE have been the most active in securing distribution deals with third parties with both Guild Home Video and CIC Video making major contributions to their catalogue. Encore Entertainment are also shaping up as a major player with a recently signed deal making them distributors for 20th Century Fox material on LaserDisc. Other distributors/labels releasing material in European markets are Tartan Video, Encore Entertainment, PolyGram Music Video, Estelle Home Video, Warner Home Video, Phonovision Entertainment, BMG Video and the UK adult label Fiona Cooper.

Unfortunately a number of major film distributors including Disney and Warner remain unrepresented. The ability of most players to play NTSC LaserDiscs enables importers to fill this gap admirably! In addition, there are sometimes cases where either the NTSC or PAL versions may be cut versions with footage removed to achieve a desired rating. This is not a one-way thing; the UK version of Basic Instinct was the uncut version since that had been allowed through on an 18 rating, while the standard US version was the R-rated version which had had nearly a minute worth of material edited out. The US special edition was the unrated version and hence complete, but at a higher cost.

Choosing between PAL and NTSC

With the ability to choose between the two colour systems without compromising the performance from the disc in the player, other considerations come into play on those occasions when both PAL and NTSC versions of the same material are available. There are no hard and fast rules as to which will prove to be better but there are some things to watch for. For video originated material, try to discover which TV system the programme was made in; the process of standards conversion invariably compromises the video image to some extent. Normally, the material will look best in the original colour system.

Material sourced from 35mm and 70mm films presents a considerably more thorny problem. Since films are shot at 24 frames per second, there is no easy way to transfer them onto either TV picture standard. To transfer to the 30 frames per second used by NTSC (EIA) video systems, technique called 3:2 pull down is used. In this, each film frame becomes alternately two and then three video fields resulting in a slightly exagerated judder in the image. For transfer to 25 frames per second (CCIR-PAL/SECAM) video systems, the film is run 4% fast, ie at 25 frames per second. This means that a 1:1 mapping of film to video frame is preserved, and the additional slight speedup both help to produce a stable and judder free picture. The down side is that the tonal quality of the voices and music is also changed; sometimes this is adjusted for but often other concerns such as preservation of Dolby Surround information come into play. In addition, the altered running time often makes it difficult to ascertain whether the film has had scenes cut from it. There is no simple answer to which is better; the 4% fast pictures of PAL (CCIR) transfers will probably look better, while the correct speed of the NTSC (EIA) transfers will make them sound better.

There are a few other issues to be aware of when making the decision. Even to this day, PAL LaserDisc mastering plants do encounter problems with extreme saturated reds (and very occasionally other colours) exhibiting fixed pattern noise due to interference between the video signal and the digital audio signal. If you know that a given film features long periods of extremely saturated reds, it may be worth considering the NTSC version or at least worth checking some of the suspect scenes on the PAL version before buying. (The Europe-LD disc reviews section may well help you on this point.) The other issue comes with letterboxed versions of films shot in some of the more extreme aspect ratios (2.35:1 etc). With these films, the number of scan lines carrying picture information can become a real problem. With the 525 line picture, as few as 270 lines may be being used to make the image; on the 625 line transfer the figure will be closer to 330 lines. Of course, the versions (as described above.) may be different making one version more attractive within a price bracket than another.

More information on World TV standards can be found in our companion web guide.

Alternatives and competitors to LaserDisc

One of the most important questions is what does the future hold for LaserDisc as a format. The simple answer is that it is unlikely to be ousted from the top end of the home entertainment market for quite some time. There has been a lot of talk about the new 12cm Video CD (aka Compact Disc Interactive [CD-I] with Full Motion Video [FMV]) taking over from LaserDisc as THE video disc format. The practical reality is that the two products are aimed at two totally different markets with very different requirements. If Video CD finds a market it will most likely be as a replacment for the VHS video cassette in the video rental arena. In this marketplace, the rapid manufacture and durability of the 12cm disc are very big plus items, and while the picture quality must be 'acceptable' there are no high demands for it. Video CD is best compared to VHS were it offers significantly lower levels of video noise but does sacrafice image quality by being based upon a single video field repeated twice rather than two seperate fields. It also suffers from a number of motion defects and colour rendering problems that may be ignored by the general public, but will be very noticable to videophiles and those with larger TV screens.

The closest competition to LaserDisc within the domestic video arena comes from SuperVHS, the high resolution High Band version of VHS. SuperVHS machines add the ability to record onto tape, while offering picture quality of a resolution approaching that of LaserDisc. SuperVHS is let down by problems inherited from VHS of colour shifting and inferior video signal to noise performance. The total absence of PAL SuperVHS pre-recorded software, and the very limited supplies of NTSC SuperVHS software conspire to also remove its competitive points as a replay medium. A great many LaserDisc player owners also have SuperVHS VCRs in order to do those things not possible with LaserDisc like recording TV programmes. The two tend to be complimentary rather than competitive in the current marketplace.

Other References

further sections on this web server

other documents


Choose: LaserDisc Players Europe LD Web Index
B.King@ee.surrey.ac.uk
17th October 1995