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DVD Frequently Asked Questions (and Answers)

This is the October 29, 2001 revision of the official Internet DVD FAQ for the rec.video.dvd Usenet newsgroups.
(See below for what's new.) Please send corrections, additions, and new questions to Jim Taylor <jtfrog@usa.net>.

This FAQ is updated at least once a month. If you are looking at a version more than a month old, it's an out-of-date copy. The most current version is at DVD Demystified.

Contents

Recent changes (last posted to newsgroups on Feb 9):

[0] Where can I get the DVD FAQ?

[0.1] Has the DVD FAQ been translated into other languages?

The following translations of the DVD FAQ are available. Translations to a few other languages are in progress.

If you'd like to translate the DVD FAQ into another language (Klingon, anyone?), please contact Jim.

[0.2] This FAQ is too long and technical. Is there a simpler version?

You betcha. Take a gander at Earl's Famous DVD Technology Exposition Web Page Extravaganza Supreme Deluxe <lonestar.texas.net/~bdub/earl/dvd.htm>.

[0.3] Is this FAQ any good? How do I know it's accurate?

Here are a few user comments on the DVD FAQ. It's the most accurate source of DVD information in this galaxy. If you find something you think is in error, please let Jim know.

Pointers to other DVD sites are scattered throughout the FAQ and in section 6.4.

[0.4] How big is this thing?

Since you asked, here are the stats as of Jan, 2001:

Size: 433 KB (443,727 bytes)
Number of words: 54,506
Number of links: 1030

If you're wondering why it's all in one big piece instead of broken into smaller pieces that would load faster, the main reason is so you can use the find feature of your browser to easily search the entire FAQ.

[1] General DVD

[1.1] What is DVD?

DVD, which once stood for digital video disc or digital versatile disc, is the next generation of optical disc storage technology. It's essentially a bigger, faster CD that can hold cinema-like video, better-than-CD audio, and computer data. DVD aims to encompass home entertainment, computers, and business information with a single digital format, eventually replacing audio CD, videotape, laserdisc, CD-ROM, and video game cartridges. DVD has widespread support from all major electronics companies, all major computer hardware companies, and all major movie and music studios. With this unprecedented support, DVD has become the most successful consumer electronics product of all time in less than three years of its introduction.

It's important to understand the difference between the physical formats (such as DVD-ROM or DVD-R) and the application formats (such as DVD-Video or DVD-Audio). DVD-ROM is the base format that holds data. DVD-Video (often simply called DVD) defines how video programs are stored on disc and played in a DVD-Video player or a DVD computer (see 4.1). The difference is similar to that between CD-ROM and Audio CD. DVD-ROM includes recordable variations DVD-R, DVD-RAM, DVD-RW, and DVD+RW (see 4.3). The application formats include DVD-Video, DVD-Video Recording, DVD-Audio (see 1.12), DVD-Audio Recording, DVD Stream Recording, and SACD. There are also special application formats for game consoles such as Sony PlayStation 2.

[1.2] What are the features of DVD-Video?

Note: Most discs do not contain all features (multiple audio/subtitle tracks, seamless branching, parental control, etc.), as each feature must be specially authored. Some discs may not allow searching or skipping.

Most players support a standard set of features:

* Must be supported by additional content on the disc.

Some players include additional features:

[1.3] What's the quality of DVD-Video?

DVD has the capability to produce near-studio-quality video and better-than-CD-quality audio. DVD is vastly superior to consumer videotape and generally better than laserdisc (see 2.8.). However, quality depends on many production factors. As compression experience and technology improves we will see increasing quality, but as production costs decrease we will also see more shoddily produced discs. A few low-budget DVDs will even use MPEG-1 encoding (which is no better than VHS) instead of higher-quality MPEG-2.

DVD video is usually encoded from digital studio master tapes to MPEG-2 format. The encoding process uses lossy compression that removes redundant information (such as areas of the picture that don't change) and information that's not readily perceptible by the human eye. The resulting video, especially when it is complex or changing quickly, may sometimes contain visual flaws, depending on the processing quality and amount of compression. At average video data rates of 3.5 to 5 Mbps (million bits/second), compression artifacts may be occasionally noticeable. Higher data rates can result in higher quality, with almost no perceptible difference from the master at rates above 6 Mbps. As MPEG compression technology improves, better quality is being achieved at lower rates.

Video from DVD sometimes contains visible artifacts such as color banding, blurriness, blockiness, fuzzy dots, shimmering, missing detail, and even effects such as a face that "floats" behind the rest of the moving picture. It's important to understand that the term "artifact" refers to anything that was not originally present in the picture. Artifacts are sometimes caused by poor MPEG encoding, but artifacts are more often caused by a poorly adjusted TV, bad cables, electrical interference, sloppy digital noise reduction, improper picture enhancement, poor film-to-video transfer, film grain, player faults, disc read errors, etc. Most DVDs exhibit few visible MPEG compression artifacts on a properly configured system.. If you think otherwise, you are misinterpreting what you see.

Some early DVD demos were not very good, but this is simply an indication of how bad DVD can be if not properly processed and correctly reproduced. Many demo discs were rushed through the encoding process in order to be distributed as quickly as possible. Contrary to common opinion, and as stupid as it may seem, these demos were not carefully "tweaked" to show DVD at its best. In-store demos should be viewed with a grain of salt, since most salespeople are incapable of properly adjusting a television set. 

Most TVs have the sharpness set too high for the clarity of DVD. This exaggerates high-frequency video and causes distortion, just as the treble control set too high for a CD causes it to sound harsh. Many DVD players output video with a black-level setup of 0 IRE (Japanese standard) rather than 7.5 IRE (US standard). On TVs that are not properly adjusted this can cause some blotchiness in dark scenes. DVD video has exceptional color fidelity, so muddy or washed-out colors are almost always a problem in the display (or the original source), not in the DVD player or disc.

DVD audio quality is superb. DVD includes the option of PCM (pulse code modulation) digital audio with sampling sizes and rates higher than audio CD. Alternatively, audio for most movies is stored as discrete, multi-channel surround sound using Dolby Digital or DTS audio compression similar to the digital surround sound formats used in theaters. As with video, audio quality depends on how well the processing and encoding was done. In spite of compression, Dolby Digital and DTS can be close to or better than CD quality.

The final assessment of DVD quality is in the hands of consumers. Most viewers consistently rate it better than laserdisc, but no one can guarantee the quality of DVD, just as no one should dismiss it based on demos or hearsay. In the end it's a matter of individual perception and the level of quality delivered by the playback system.

[1.4] What are the disadvantages of DVD?

[1.5] What DVD players and drives are available?

Some manufacturers originally announced that DVD players would be available as early as the middle of 1996. These predictions were woefully optimistic. Delivery was initially held up for "political" reasons of copy protection demanded by movie studios, but was later delayed by lack of titles. The first players appeared in Japan in November, 1996, followed by U.S. players in March, 1997. Players slowly trickled in to other regions. Now, almost four years after the initial launch, over two hundred models of DVD players are available from dozens of electronics companies. Prices for the first players were $1000 and up. By the end of 2000, players were available for under $100 at discount retailers.

See section 6.2 for a list of companies that provide DVD players.

Fujitsu supposedly released the first DVD-ROM-equipped computer on Nov. 6 in Japan. Toshiba released a DVD-ROM-equipped computer and a DVD-ROM drive in Japan in early 1997 (moved back from December which was moved back from November). DVD-ROM drives from Toshiba, Pioneer, Panasonic, Hitachi, and Sony began appearing in sample quantities as early as January 1997, but none were to be available before May. The first upgrade kits (combination DVD-ROM drive and decoder hardware) became available from Creative Labs, Hi-Val, and Diamond Multimedia in April and May of 1997.

Today, every major PC manufacturer has models that include DVD-ROM drives. The price difference from the same system with a CD-ROM drive ranges from $30 to $200 (laptops have more expensive drives). Upgrade kits for older computers are available for $100 to $700 from Creative Labs, DynaTek, E4 (Elecede), Hi-Val, Leadtek, Margi Systems (for laptops), Media Forte, Pacific Digital, Sigma Designs, Sony, STB Systems, Toshiba, Utobia, and others. For more information about DVDs on computers, including writable DVD drives, see section 4.

Note: If you buy a player or drive from outside your country (e.g., a Japanese player for use in the US) you may not be able to play region-locked discs on it. (See 1.10.)

More information:

[1.5.1] Which player should I buy?

There are many good players available. Video and audio performance in all modern DVD players is excellent. Personal preferences, your budget, and your existing home theater setup all play a large role in what player is best for you. Unless you have a high-end home theater setup, a player that costs under $400 should be completely adequate. Make a list of things that are important to you (such as ability to play CD-Rs, ability to play Video CDs, 96 kHz/24-bit audio decoding, DTS Digital Out, internal 6-channel Dolby Digital decoder) to help you come up with a set of players. Then try out a few of the players in your price range, focusing on ease of use (remote control design, user interface, front-panel controls). Since there is not a big variation in picture quality and sound quality within a given price range, convenience features play a big part. The remote control, which you'll use all the time, can drive you crazy if it doesn't suit your style.

Some players, especially cheaper models, don't properly play all discs. Before buying a player, you may want to test it with a few complex discs such as The Matrix, The Abyss, Independence Day, and DVD Demystified. See 1.41 for more information.

In certain cases, you might want to buy a DVD PC instead of a standard DVD player, especially if you want progressive video. See 1.40 and 4.1. 

Here are a few questions to ask yourself.

- Do I want selectable sound tracks and subtitles, multiangle viewing, aspect ratio control, parental/multirating features, fast and slow playback, great digital video, multichannel digital audio, compatibility with Dolby Pro Logic receivers, on-screen menus, dual-layer playback, and ability to play audio CDs? If so, this is the wrong question to ask yourself, since all DVD players have all of these features.
- Do I want DTS audio? If so, look for a player with the "DTS Digital Out" logo. (See 3.6.2.) 
- Do I want to play Video CDs? If so, check the specs for Video CD compatibility. (See 2.4.5.)
- Do I need a headphone jack?
- Do I want player setup menus in languages other than English? If so, look for multilanguage setup feature. (Note: the multilanguage menus on certain discs are supported by all players.)
- Do I want to play homemade CD-R audio discs? If so look for the "dual laser" feature. (See 2.4.3.)
- Do I want to replace my CD player? If so, you might want a changer that can hold 3, 5, or even hundreds of discs.
- Do I want to control all my entertainment devices with one remote control? If so, look for a player with a programmable universal remote, or make sure your existing universal remote is compatible with the DVD player.
- Do I want to zoom in to check details of the picture? If so, look for players with picture zoom.
- Do I want to play HDCDs? If so, check for the HDCD logo. (See 2.4.13.)
- Does my receiver have only optical or only coax digital audio inputs? If so, make sure the player has outputs to match. (See 3.2.)
- Do I care about black-level adjustment?
- Do I appreciate special deals? If so, look for free DVD coupons and free DVD rentals that are available with many players.

For more information, read hardware reviews at Web sites such as DVDFile or in magazines such as Widescreen Review. You may also want to read about user experiences at Audio Review and in online forums at Home Theater Forum and DVDFile. There's more advice at DVDBuyingGuide and at eCoustics.com, which also has a list of links to reviews on other sites.

See sections 3.1 and 3.2 for specific information on what audio/video connections are needed to fit into your existing setup.

[1.6] What DVD titles are available?

DVD started off slowly. Rosy predictions of hundreds of movie titles for Christmas of 1996 failed to materialize. Only a handful of DVD titles, mostly music videos, were available in Japan for the November 1996 launch of DVD. The first actual feature films appeared in Japan in December 20 (The Assassin, Blade Runner, Eraser, and The Fugitive from Warner Home Video). By April there were over 150 titles in Japan. The first titles released in the U.S., on March 19, 1997, by Lumivision, authored by AIX Entertainment, were IMAX adaptations: Africa: The Serengeti, Antarctica: An Adventure of a Different Nature, Tropical Rainforest, and Animation Greats. (Other movies such as Batman and Space Jam were demonstrated earlier, but were not full versions available for sale.) The Warner Bros. U.S. launch followed on March 24, but was limited to seven cities.  Almost 19,000 discs were purchased in the first two weeks of the US launch -- more than expected. InfoTech predicted over 600 titles by the end of 1997 and more than 8,000 titles by 2000. By December 1997, over 1 million individual DVD discs were shipped. By the end of 1999, over 100 million discs had shipped. By the end of 2000 there were over 10,000 titles available in the US and over 15,000 worldwide. Compared to other launches (CD, LD, etc.) this is a huge number in a very short time.

See 6.3 for a list of Web sites where you can buy or rent DVDs.

Availability of DVD hardware and software in Europe runs about a year behind the US. A number of launches were announced with little follow-through, but DVD began to become established in Europe around the end of 1998.

Doug MacLean has a searchable and downloadable database of region 1 movie titles at <www.hometheaterinfo.com/dvdlist.htm>. Perry Denton has a text list of region 1 titles at <www.surroundfreak.com/dvd/dvd1.htm>. 7th Zone has a searchable list of region 1 and region 2 titles. Also check out the Internet Movie Database's DVD Browser or the searchable and downloadable database from the DVD Entertainment Group. There are also good searchable databases at DVD File, Express.com, and DVD Planet. For a list of widescreen-specific DVD titles, visit Widescreen Review.

DVD-ROM computer software is slowly appearing. See 6.2 for a list. Many initial DVD-ROM titles are only be available as part of a hardware or software bundle until the market grows larger. IDC expected that over 13 percent of all software would be available in DVD-ROM format by the end of 1998, but reality didn't meet expectations. In one sense, DVD-ROMs are simply larger faster CD-ROMs and will contain the same material. But DVD-ROMs can also take advantage of the high-quality video and multi-channel audio capabilities being added to many DVD-ROM-equipped computers.

[1.6.1] Where can I read reviews of DVDs?

The following sites have reviews of at least 800 discs. Also see the list of DVD review sites at Yahoo.

[1.6.2] How do I find out when a movie will be available on DVD?

First, check one of the lists and databases mentioned in 1.6 to make sure it's not already available. Then check the upcoming release lists at DVD Review and Laser Scans. There's also the release list at Image Entertainment. A good source of info about unannounced titles is The Digital Bits Rumor Mill.

[1.7] How much do players and drives cost?

Mass-market DVD movie players currently list for $140 to $3000. (See 1.5 for more information.) DVD-ROM drives and upgrade kits for computers sell for around $50 to $600. (OEM drive prices are around $60.) Prices are expected to eventually drop to current CD-ROM drive levels.

[1.8] How much do discs cost?

It varies, but most DVD movies list for $20 to $30 with street prices between $15 and $25, even those with supplemental material. Low-priced movies can be found for under $10. So far DVD has not followed the initial high rental-price model of VHS.

DVD-ROMs are usually slightly more expensive than CD-ROMs since there is more on them, they cost more to replicate, and the market is smaller. But once production costs drop and the installed base of drives grow, DVD-ROMs will cost about the same as CD-ROMs today.

[1.9] How is DVD doing? Where can I get statistics?

DVD did not take off quite as fast as some early predictions, but it has sold faster than videotape, CD, and laserdisc. In fact, before its third birthday in March 2000, DVD had become the most successful consumer electronics entertainment product ever.

Here are some predictions:

Here's reality:

For comparison, there were about 700 million audio CD players and 160 million CD-ROM drives worldwide in 1997. 1.2 billion CD-ROMs were shipped worldwide in 1997 from a base of about 46,000 different titles. There were about 80 million VCRs in the U.S. (89% of households) and about 400 million worldwide. 110,000 VCRs shipped in the first two years after release. Nearly 16 million VCRs were shipped in 1998. In 2000 there were about 270 million TVs in the U.S. and 1.3 billion worldwide.When DVD came out in 1997 there were about 3 million laserdisc players in the U.S. 

For latest U.S. player sales statistics, see the CEA page at The Digital Bits. Other DVD statistics and forecasts can be found at IRMA, MediaLine, Twice. Industry analyses and forecasts can be purchased from Adams Media Research, British Video Association, Cahners In-stat, Centris, Datamonitor, Dataquest, DVD Intelligence, eBrain, International Data Corporation (IDC), InfoTech, Jon Peddie Associates (JPA), Paul Kagan Associates, Screen Digest, SIMBA Information, Strategy Analytics, Understanding & Solutions and others.

[1.10] What are "regional codes," "country codes," or "zone locks"?

Motion picture studios want to control the home release of movies in different countries because theater releases aren't simultaneous (a movie may come out on video in the U.S. when it's just hitting screens in Europe). Also, studios sell distribution rights to different foreign distributors and would like to guarantee an exclusive market. Therefore they required that the DVD standard include codes that can be used to prevent playback of certain discs in certain geographical regions. Each player is given a code for the region in which it's sold. The player will refuse to play discs that are not coded for its region. This means that discs bought in one country may not play on players bought in another country. Some people believe that region codes are an illegal restraint of trade, but there have been no legal cases to establish this.

Regional codes are entirely optional for the maker of a disc. Discs without region locks will play on any player in any country. It's not an encryption system, it's just one byte of information on the disc that the player checks. Some studios originally announced that only their new releases would have regional codes, but so far almost all Hollywood releases play in only one region. Region codes are a permanent part of the disc, they won't "unlock" after a period of time. Region codes do not apply to DVD-Audio.

There are 8 regions (also called "locales"). Players and discs are often identified by the region number superimposed on a world globe. If a disc plays in more than one region it will have more than one number on the globe.
1: U.S., Canada, U.S. Territories
2: Japan, Europe, South Africa, and Middle East (including Egypt)
3: Southeast Asia and East Asia (including Hong Kong)
4: Australia, New Zealand, Pacific Islands, Central America, Mexico, South America, and the Caribbean
5: Eastern Europe (Former Soviet Union), Indian subcontinent, Africa, North Korea, and Mongolia
6: China
7: Reserved
8: Special international venues (airplanes, cruise ships, etc.)
(See the map at <www.unik.no/~robert/hifi/dvd/world.html>.)

Technically there is no such thing as a region 0 disc or a region 0 player. There is such thing as an all-region disc. There are also all-region players. Some players can be "hacked" with special command sequences from the remote control to switch regions or play all regions. Some players can be physically modified ("chipped") to play discs regardless of the regional codes on the disc. This usually voids the warranty, but is not illegal in most countries. (The only thing that requires player manufacturers to region-code their players is the CSS license. See 1.11) On Feb. 7, 2001, NASA sent two multiregion DVD players to the International Space Station.

Some discs from Fox, Buena Vista/Touchstone/Miramax, MGM/Universal, Polygram, and Columbia TriStar contain program code that checks for the proper region setting in the player. (There's Something About Mary and Psycho are examples.) In late 2000, Warner Bros. began using the same active region code checking that other studios had been using for over a year. They called it "region code enhancement" (RCE, also known as REA), and it received much publicity. RCE was first added to discs such as The Patriot and Charlie's Angels. "Smart discs" with active region checking won't play on code-free players that are set for all regions (FFh), but they can be played on manual code-switchable players that allow you to change the region using the remote control. They may not work on auto-switching players that recognize and match the disc region. (It depends on the default region setting of the player. An RCE disc has all its region flags set so that the player doesn't know which one to switch to, then it queries the player for the region setting and aborts if it's the wrong one. A default player setting of region 1 will fool RCE discs from region 1. Playing a region 1 disc for a few seconds will set most auto-switching players to region 1 and allow them to play an RCE disc.) When an RCE disc detects the wrong region or an all-region player, it will usually put up a message saying that the player may have been altered and that the disc is not compatible with the player. A serious side effect is that some legitimate players fail the test, such as the Fisher DVDS-1000.

There was much wailing and gnashing of teeth when RCE first appeared, but DVD fans quickly learned that it only affected some players. Makers of player modification kits that didn't work with RCE soon modified their chips to get around it. For every higher wall there is a taller ladder. See DVDTalk's RCE FAQ for more info and workarounds.

Information about modifying players and buying region-free players can be found on the Internet (at sites such as Code Free DVD, Region Free DVD, dvdkits.com, DVD Upgrades, DVD In the World, DVDoverseas, Link Electronics, MPEGX.com PlanetDVD, 7thZone, Techtronics, Upgrade Heaven, and <www.brouhaha.com/~eric/video/dvd/>; for Mac: DVD Utilities for Macintosh) and in the rec.video.dvd newsgroups (searchable at Deja.com). There's more codefree player info at DVDCity.

Regional codes apply to game consoles such as PlayStation 2 and Xbox, but only for DVD-Video (movie) discs (see DVDRegionX for region modifications to PS2). PlayStation has a separate regional lockout scheme for games. Regional codes also apply to DVD-ROM systems, but affect only DVD-Video discs, not DVD-ROM discs containing computer software. Computer playback systems check for regional codes before playing movies from a CSS-protected DVD-Video (see 1.11 for CSS info). Newer RPC2 DVD-ROM drives let you change the region code several times. (RPC stands for region protection control.) Once an RPC2 drive has reached the limit of 5 changes it can't be changed again unless the vendor or manufacturer resets the drive. The Drive Info utility can tell you if you have an RPC2 drive (it will say "This drive has region protection"). Drive Info and information about circumventing DVD-ROM region restrictions is available from Internet sites such as Visual Domain and DVD Infomatrix, as well as links listed above. After December 31, 1999, only RPC2 drives are being manufactured.

In addition to region codes, there are also differences in discs for NTSC and PAL TV systems (see 1.19).

[1.11] What are the copy protection issues?

CPSA (content protection system architecture) is the name given to the overall framework for security and access control across the entire DVD family. Developed by the "4C" entity (Intel, IBM, Matsushita, and Toshiba) in cooperation with the Copy Protection Technical Working Group (CPTWG), it covers encryption, watermarking, protection of analog and digital outputs, and so on. There are many forms of content protection that apply to DVD.

1) Analog CPS (Macrovision)
Videotape (analog) copying is prevented with a Macrovision 7.0 or similar circuit in every player. The general term is APS (Analog Protection System), also sometimes called copyguard. Computer video cards with composite or s-video (Y/C) output must also use APS. Macrovision adds a rapidly modulated colorburst signal ("Colorstripe") along with pulses in the vertical blanking signal ("AGC") to the composite video and s-video outputs. This confuses the synchronization and automatic-recording-level circuitry in 95% of consumer VCRs. Unfortunately, it can degrade the picture, especially with old or nonstandard equipment. Macrovision may show up as stripes of color, distortion, rolling, black & white picture, and dark/light cycling. Macrovision creates problems for most TV/VCR combos (see 3.2.1) and some high-end equipment such as line doublers and video projectors. Macrovision was not present on analog component video output of early players, but is required on newer players (AGC only, since there is no burst in a component signal). The discs contain "trigger bits" telling the player whether or not to enable Macrovision AGC, with the optional addition of 2-line or 4-line Colorstripe. The triggers occur about twice a second, which allows fine control over what part of the video is protected. The producer of the disc decides what amount of copy protection to enable and then pays Macrovision royalties accordingly (several cents per disc). Just as with videotapes, some DVDs are Macrovision-protected and some aren't. (For a few Macrovision details see STMicroelectronics' NTSC/PAL video encoder datasheets at <www.st.com/stonline/books/>.) There are inexpensive devices that defeat Macrovision, although only a few work with the new Colorstripe feature. These devices go under names such as Video Clarifier, Image Stabilizer, Color Corrector, and CopyMaster. Or you can build your own. Professional time-base correctors (TBCs) that regenerate line 21 also remove Macrovision. APS affects only video, not audio. 

2) CGMS
Each disc also contains information specifying if the contents can be copied. This is a "serial" copy generation management system (SCMS) designed to prevent copies or copies of copies. The CGMS information is embedded in the outgoing video signal. For CGMS to work, the equipment making the copy must recognize and respect the CGMS information. The analog standard (CGMS-A) encodes the data on NTSC line 21 (in the XDS service) or line 20. CGMS-A is recognized by most digital camcorders and by some computer video capture cards (they will flash a message such as "recording inhibited"). Professional time-base correctors (TBCs) that regenerate lines 20 and 21 will remove CGMS-A information from an analog signal. The digital standard (CGMS-D) is not yet finalized, but will apply to digital connections such as IEEE 1394/FireWire. See section 6, below.

3) Content Scrambling System (CSS)
Because of the potential for perfect digital copies, paranoid movie studios forced a deeper copy protection requirement into the DVD standard. Content Scrambling System (CSS) is a data encryption and authentication scheme intended to prevent copying video files directly from DVD-Video discs. CSS was developed primarily by Matsushita and Toshiba. Each CSS licensee is given a key from a master set of 400 keys that are stored on every CSS-encrypted disc. This allows a license to be revoked by removing its key from future discs. The CSS decryption algorithm exchanges keys with the drive unit to generate an encryption key that is then used to obfuscate the exchange of disc keys and title keys that are needed to decrypt data from the disc. DVD players have CSS circuitry that decrypts the data before it's decoded and displayed. On the computer side, DVD decoder hardware and software must include a CSS decryption module. All DVD-ROM drives have extra firmware to exchange authentication and decryption keys with the CSS module in the computer. Beginning in 2000, new DVD-ROM drives are required to support regional management in conjunction with CSS (see 1.10 and 4.1). Makers of equipment used to display DVD-Video (drives, decoder chips, decoder software, display adapters, etc.) must license CSS. There is no charge for a CSS license, but it's a lengthy process, so it's recommended that interested parties apply early. CSS is administered by the DVD DVD Copy Control Association (DVD CCA). Near the end of May 1997, CSS licenses were finally granted for software decoding. The license is extremely restrictive in an attempt to keep the CSS algorithm and keys secret. Of course, nothing that's used on millions of players and drives worldwide could be kept secret for long. In October 1999, the CSS algorithm was cracked and posted on the Internet, triggering endless controversies and legal battles (see 4.8).

4) Content Protection for Prerecorded Media (CPPM)
CPPM is used only for DVD-Audio. It was developed to improve on CSS. Keys are stored in the lead-in area, but unlike CSS there are no title keys in the sector headers. Each volume has a 56-bit "album identifier," similar to a CSS disc key, stored in the control area. Each disc contains a media key block, stored in a file in the clear on the disc. The media key block data is logically ordered in rows and columns that are used during the authentication process to generate a decryption key from a specific set of player keys (device keys). If the device key is revoked, the media key block processing step will result in an invalid key value. As with CSS, the media key block can be updated to revoke the use of compromised player keys. The authentication mechanism is the same as for CSS, so no changes are required to existing drives. A disc may contain both CSS and CPPM content if it is a hybrid DVD-Video/DVD-Audio disc.

5) Content Protection for Recordable Media (CPRM)
CPRM is a mechanism that ties a recording to the media on which it is recorded. It is supported by all DVD recorders released after 1999. Each blank recordable DVD has a unique 64-bit media ID etched in the BCA (see 3.11). When protected content is recorded onto the disc, it can be encrypted with a 56-bit C2 (Cryptomeria) cipher derived from the media ID. During playback, the ID is read from the BCA and used to generate a key to decrypt the contents of the disc. If the contents of the disc are copied to other media, the ID will be absent or wrong and the data will not be decryptable.

6) Digital Copy Protection System (DCPS)
In order to provide for digital connections between components without allowing perfect digital copies, five digital copy protection systems were proposed to the CEA. The frontrunner is DTCP (digital transmission content protection), which focuses on IEEE 1394/FireWire but can be applied to other protocols. The draft proposal (called 5C, for the five companies that developed it) was made by Intel, Sony, Hitachi, Matsushita, and Toshiba in February 1998. Sony released a DTCP chip in mid 1999. Under DTCP, devices that are digitally connected, such as a DVD player and a digital TV or a digital VCR, exchange keys and authentication certificates to establish a secure channel. The DVD player encrypts the encoded audio/video signal as it sends it to the receiving device, which must decrypt it. This keeps other connected but unauthenticated devices from stealing the signal. No encryption is needed for content that is not copy protected. Security can be "renewed" by new content (such as new discs or new broadcasts) and new devices that carry updated keys and revocation lists (to identify unauthorized or compromised devices). A competing proposal, XCA (extended conditional access), from Zenith and Thomson, is similar to DTCP but can work with one-way digital interfaces (such as the EIA-762 RF remodulator standard) and uses smart cards for renewable security. Other proposals have been made by MRJ Technology, NDS, and Philips. In all five proposals, content is marked with CGMS-style flags of "copy freely", "copy once," "don't copy," and sometimes "no more copies". Digital devices that do nothing more than reproduce audio and video will be able to receive all data (as long as they can authenticate that they are playback-only devices). Digital recording devices are only able to receive data that is marked as copyable, and they must change the flag to "don't copy" or "no more copies" if the source is marked "copy once." DCPS in general is designed for the next generation of digital TVs, digital receivers, and digital video recorders. It will require new DVD players with digital connectors (such as those on DV equipment). These new products won't appear until 2001 at the earliest. Since the encryption is done by the player, no changes are needed to existing discs.

7) High-Bandwidth Digital Content Protection (HDCP)
HDCP is similar to DTCP, but designed for digital video monitor interfaces such as DVI. In 1998, the Digital Display Working Group (DDWG) was formed to create a universal interface standard between computers and displays to replace the analog VGA connection standard. The resulting Digital Visual Interface (DVI) specification, released in April 1999, was based on Silicon Image's PanelLink technology, which at 4.95 Gbps can support 1600×1200 (UXGA) resolution, which covers all the HDTV resolutions. Many new HDTV displays are likely to have both IEEE 1394 and DVI connections. Intel proposed a security component for DVI: High-Bandwidth Digital Content Protection. HDCP provides authentication, encryption, and revocation. Special hardware on the video adapter card and the display monitor encrypts video data before it is sent over the link. When an HDCP-equipped DVI card senses that the connected monitor does not support HDCP, it lowers the image quality of protected content. The HDCP key exchange process verifies that a receiving device is authorized to display or record video. It uses an array of forty 56-bit secret device keys and a 40-bit key selection vector -- all supplied by the HDCP licensing entity. If the security of a display device is compromised, its key selection vector is placed on the revocation list. The host device has the responsibility of maintaining the revocation list, which is updated by system renewability messages (SRMs) carried by newer devices and by video content. Once the authority of the receiving device has been established, the video is encrypted by an exclusive-or operation with a stream cipher generated from keys exchanged during the authentication process. If a display device with no decryption ability attempts to display encrypted content, it appears as random noise.

The first four forms of copy protection are optional for the producer of a disc. Movie decryption is also optional for hardware and software playback manufacturers: a player or computer without decryption capability will only be able to play unencrypted movies. CPRM is handled automatically by DVD recorders. DCPS and HDCP will be performed by the DVD player, not by the disc developer.

These copy protection schemes are designed only to guard against casual copying (which the studios claim causes billions of dollars in lost revenue). The goal is to "keep the honest people honest." The people who developed the copy protection standards are the first to admit that they won't stop well-equipped pirates.

Movie studios have promoted legislation making it illegal to defeat DVD copy protection. The result is the World Intellectual Property Organization (WIPO) Copyright Treaty and the WIPO Performances and Phonograms Treaty (December 1996) and the compliant U.S. Digital Millennium Copyright Act (DMCA), passed into law in October 1998. Software intended specifically to circumvent copy protection is now illegal in the U.S. and many other countries. A co-chair of the legal group of the DVD copy protection committee stated, "in the video context, the contemplated legislation should also provide some specific assurances that certain reasonable and customary home recording practices will be permitted, in addition to providing penalties for circumvention." It's not at all clear how this might be "permitted" by a player or by studios that routinely set the "don't copy" flag on all their discs.

DVD-ROM drives and computers, including DVD-ROM upgrade kits, are required to support Macrovision, CGMS, and CSS. PC video cards with TV outputs that don't support Macrovision will not work with encrypted movies. Computers with IEEE 1394/FireWire connections must support the final DCPS standard in order to work with other DCPS devices. Every DVD-ROM drive must include CSS circuitry to establish a secure connection to the decoder hardware or software in the computer, although CSS can only be used on DVD-Video content. Of course, since a DVD-ROM can hold any form of computer data, other encryption schemes can be implemented. See 4.1 for more information on DVD-ROM drives.

The Watermarking Review Panel (WaRP) --the successor to the Data-Hiding Sub-Group (DHSG)-- of the CPTWG selected an audio watermarking system that has been accepted by the DVD Forum for DVD-Audio (see 1.12). The original seven video watermarking proposals were merged into three: IBM/NEC, Hitachi/Pioneer/Sony, and Macrovision/Digimarc/Philips. On February 17, 1999, the first two groups combined to form the "Galaxy Group" and merged their technologies into a single proposal. The second group has dubbed their technology "Millennium." Watermarking permanently marks each digital audio or video frame with noise that is supposedly undetectable by human ears or eyes. Watermark signatures can be recognized by playback and recording equipment to prevent copying, even when the signal is transmitted via digital or analog connections or is subjected to video processing. Watermarking is not an encryption system, but rather a way to identify whether a copy of a piece of video or audio is allowed to be played. New players and software are required to support watermarking, but the DVD Forum intends to make watermarked discs compatible with existing players. There were reports that the early watermarking technique used by Divx caused visible "raindrop" or "gunshot" patterns, but the problem was apparently solved for later releases.

[1.12] What about DVD-Audio or Music DVD?

When DVD was released in 1996 there was no DVD-Audio format, although the audio capabilities of DVD-Video far surpassed CD. The DVD Forum sought additional input from the music industry before defining the DVD-Audio format. A draft standard was released by the DVD Forum's Working Group 4 (WG4) in January 1998, and version 0.9 was released in July. The final DVD-Audio 1.0 specification (minus copy protection) was approved in February 1999 and released in March, but products were delayed in part by the slow process of selecting copy protection features (encryption and watermarking), with complications introduced by the Secure Digital Music Initiative (SDMI). The scheduled October 1999 release was further delayed until mid 2000, ostensibly because of concerns caused by the CSS crack (see 4.8), but also because the hardware wasn't quite ready, production tools aren't up to snuff, and there is lackluster support from music labels. Pioneer released some early models of DVD-Audio players in Japan in late 1999, but they don't play copy-protected discs.

Matsushita released Panasonic and Technics brand universal DVD-Audio/DVD-Video players available in July 2000 for $700 to $1,200. Pioneer, JVC, Yamaha, and others released DVD-Audio players in fall 2000 and early 2001. By the end of 2000 there were about 50 DVD-Audio titles available.

DVD-Audio is a separate format from DVD-Video. DVD-Audio discs can be designed to work in DVD-Video players, but it's possible to make a DVD-Audio disc that won't play at all in a DVD-Video player, since the DVD-Audio specification includes new formats and features, with content stored in a separate "DVD-Audio zone" on the disc (the AUDIO_TS directory) that DVD-Video players never look at. New DVD-Audio players are needed, or new "universal players" that can play both DVD-Video and DVD-Audio discs. Universal players are also called VCAPs (video-capable audio players).

Plea to producers: Universal players won't be available for some time, but you can make universal discs today. With a small amount of effort, all DVD-Audio discs can be made to work on all DVD players by including a Dolby Digital version of the audio in the DVD-Video zone.
Plea to DVD-Audio authoring system developers: Make your software do this by default or strongly recommend this option during authoring.

DVD-Audio players (and universal players) work with existing receivers. They output PCM and Dolby Digital, and some will support the optional DTS and DSD formats. However, most current receivers can't decode high-definition, multichannel PCM audio (see 3.6.1 for details), and even if they could it can't be carried on standard digital audio connections. DVD-Audio players with high-end digital-to-analog converters (DACs) can only be hooked up to receivers with 2-channel or 6-channel analog inputs, but some quality is lost if the receiver converts back to digital for processing. Future receivers with improved digital connections such as IEEE 1394 (FireWire) will be needed to use the full digital resolution of DVD-Audio.

DVD audio is copyright protected by an embedded signaling or digital watermark feature. This uses signal processing technology to apply a digital signature and optional encryption keys to the audio in the form of supposedly inaudible noise so that new equipment will recognize copied audio and refuse to play it. Proposals from Aris, Blue Spike, Cognicity, IBM, and Solana were evaluated by major music companies in conjunction with the 4C Entity, comprising IBM, Intel, Matsushita, and Toshiba. Aris and Solana merged to form a new company called Verance, whose Galaxy technology was chosen for DVD-Audio in August 1999. (In November 1999, Verance watermarking was also selected for SDMI.) Verance and 4C claimed that tests on the Verance watermarking method showed it was inaudible, but golden-eared listeners in later tests were able to detect the watermarking noise.

Sony and Philips have developed a competing Super Audio CD format that uses DVD discs. (See 3.6.1 for details.) Sony released version 0.9 of the SACD spec in April 1998, the final version appeared in April (?) 1999. SACD technology is available to existing Sony/Philips CD licensees at no additional cost. Most initial SACD releases have been mixed in stereo, not multichannel. SACD was originally supposed to provide "legacy" discs with two layers, one that plays in existing CD players, plus a high-density layer for DVD-Audio players, but technical difficulties kept dual-format discs from being produced until the end of 2000, and only then in small quantities. Pioneer, which released the first DVD-Audio players in Japan at the end of 1999, included SACD support in their DVD-Audio players. If other manufacturers follow suit, the entire SACD vs. DVD-Audio standards debate could be moot, since DVD-Audio players would play both types of discs.

Sony released an SACD player in Japan in May 1999 at the tear-inducing price of $5,000. The player was released in limited quantities in the U.S. at the end of 1999. Philips released a $7,500 player in May 2000. Sony shipped a $750 SACD player in Japan in mid 2000. About 40 SACD titles were available at the end of 1999, from studios such as DMP, Mobile Fidelity Labs, Pioneer, Sony, and Telarc.

A drawback related to DVD-Audio and SACD players is that most audio receivers with 6 channels of analog input aren't able to do bass management. Receivers with Dolby Digital and DTS decoders handle bass management internally, but most receivers with 6-channel audio inputs simply pass them through to the amplifier. Until new audio systems with full bass management from 6-channel inputs are developed, any setup that doesn't have full-range speakers for all 5 surround channels will not properly reproduce all the bass frequencies. In the interim, you may be able to use an outboard bass managment box, such as from Outlaw Audio.

If you are interested in making the most of a DVD-Audio or SACD player, you need a receiver with 6-channel analog audio inputs. You also need 5 full-frequency speakers (that is, each speaker should be able to handle subwoofer frequencies) and a subwoofer, unless you have a receiver that can perform bass management on the analog inputs.

For more on DVD-Audio, particularly various player models, visit Digital Audio Guide.

[1.13] Which studios are supporting DVD?

All major movie studios, most major music studios.

When DVD players became available in early 1997, Warner and Polygram were the only major movie studios to release titles. Additional titles were available from small publishers. The other studios gradually joined the DVD camp (see 6.2 for a full list, see 1.6 for movie info). Dreamworks was the last significant studio to announce full DVD support. Paramount, Fox, and Dreamworks initially supported only Divx, but in summer 1998 they each announced support for open DVD.

[1.14] Can DVD record from VCR/TV/etc?

Short Answer: Yes, but it will cost you. Most of the major DVD player manufacturers have announced DVD home video recorders. (See 4.3.)

Long answer: Recording analog video to DVD is a very tricky process. The minimum requirement for reproducing audio and video on DVD is an MPEG video stream and a PCM audio track. (Other streams such as Dolby Digital audio, MPEG audio, and subpicture are not necessary for the simplest case.) Basic DVD control codes are also needed. It's difficult in real time to encode the video and audio, combine them with DVD-Video info, and write the whole thing to a recordable DVD disc, especially in a form that's compatible with standard DVD-Video players. This is still extremely expensive for a home recorder, even though prices for DVD production systems have dropped over the space of three years from millions of dollars to thousands of dollars to hundreds of dollars for the simplest packages.

Other obstacles: Blank discs cost about $10 (although they will get cheaper over time). Real-time compression requires higher bit rates for decent quality, thus lowering capacity. MPEG-2 compression works much better with high-quality source, so recording from VHS or broadcast/cable may not give very good results (unless the DVD recorder has special prefilters, which increases the cost).

Don't be confused by DVD-R drives, DVD-RAM drives, or other recordable DVD drives for computers (see 4.3). These existing recorders can store data, but to create full-featured DVD-Videos requires additional hardware and software to do video encoding (MPEG), audio encoding (Dolby Digital, MPEG, or PCM), subpicture encoding (run-length-compressed bitmaps), still frame encoding (MPEG), navigation and control data generation, and multiplexing.

In spite of all the difficulties, many of the major DVD manufacturers are working on recordable DVD for the home. DVD video recorders appeared in Japan at the end of 1999, and began appearing elsewhere at the end of 2000. Early units were expensive: $2,500 to $4,000. At some point, DVD recorder/players will be built into satellite and cable receivers, hard-disk video recorders, and similar boxes. 

Some people believe that recordable DVD-Video will never be practical for consumers to record TV shows or home videos, since digital tape is more cost effective. On the other hand, digital tape lacks many of the advantages of DVD such as seamless branching, instant rewind/fast forward, instant search, and durability, not to mention the coolness of small shiny discs. Once the encoding technology is fast and cheap enough, and blank discs are cheap enough, recordable DVD will reach the mainstream.

[1.15] What happens if I scratch the disc? Aren't discs too fragile to be rented?

Most scratches will cause minor channel data errors that are easily corrected. That is, data is stored on DVDs using powerful error correction techniques that can recover from scratches as big as 6 millimeters with no loss of data. A common misperception is that a scratch will be worse on a DVD than on a CD because of higher storage density and because video is heavily compressed. DVD data density (say that fast ten times!) is physically four times that of CD-ROM, so it's true that a scratch will affect more data. But DVD error correction is at least ten times better than CD-ROM error correction and more than makes up for the density increase. It's also important to realize that MPEG-2 and Dolby Digital compression are partly based on removal or reduction of imperceptible information, so decompression doesn't expand the data as much as might be assumed. Major scratches may cause uncorrectable errors that will produce an I/O error on a computer or show up as a momentary glitch in DVD-Video picture. Paradoxically, sometimes the smallest scratches can cause the worst errors (because of the particular orientation and refraction of the scratch). There are many schemes for concealing errors in MPEG video, which may be used in future players.

See 1.39 for information on care and cleaning of DVDs.

The DVD computer advisory group specifically requested no mandatory caddies or other protective carriers. Consider that laserdiscs, music CDs, and CD-ROMs are likewise subject to scratches, but many video stores and libraries rent them. Major chains such as Blockbuster and West Coast Entertainment rent DVDs in many locations. So far most reports of rental disc performance are positive. A nice list of DVD rental outlets is at <home.earthlink.net/~tlfordham/rental.html>.

[1.16] VHS is good enough, why should I care about DVD?

The primary advantages of DVD are quality and extra features (see 1.2). DVD will not degrade with age or after many playings like videotape will (which is an advantage for parents with kids who watch Disney videos twice a week!). This is the "collectability" factor present with CDs vs. cassette tapes.

If none of this matters to you, then VHS probably is good enough.

[1.17] Is the packaging different from CD?

Manufacturers are worried about customers assuming DVDs will play in their CD player, so they would like the packaging to be different. There are a number of DVD packages that are as wide as a CD jewel box (about 5-5/8") and as tall as a VHS cassette box (about 7-3/8"), as recommended by the Video Software Dealers Association (VSDA). However, no one is being forced to use a larger package size. Some companies use standard jewel cases or paper and vinyl sleeves. Divx discs came in paperboard and plastic Q-Pack cases the same size as a CD jewel case.

Most movies are packaged in the Amaray "keep case," an all-plastic clamshell with clear vinyl pockets for inserts, that's popular among consumers. Time Warner's "snapper," a paperboard case with a plastic lip, is less popular. There's also a "super jewel box," the stretch-limo version of a CD jewel case, that's common in Europe. 

[1.18] What's a dual-layer disc? Will it work in all players?

A dual-layer disc has two layers of data, one of them semi-transparent so that the laser can focus through it and read the second layer. Since both layers are read from the same side, a dual-layer disc can hold almost twice as much as a single-layer disc, typically 4 hours of video (see 3.3 for more details). Many discs use dual layers. Initially only a few replication plants could make dual-layer discs, but most plants now have the capability. The second layer can use either a PTP (parallel track path) layout where both tracks run in parallel (for independent data or special switching effects), or an OTP (opposite track path) layout where the second track runs in an opposite spiral; that is, the pickup head reads out from the center on the first track then in from the outside on the second track. The OTP layout is designed to provide continuous video across both layers. The layer change can occur anywhere in the video; it doesn't have to be at a chapter point. There's no guarantee that the switch between layers will be seamless. The layer change is invisible on some players, but it can cause the video to freeze for a fraction of a second or up to 4 seconds on other players. The "seamlessness" depends as much on the way the disc is prepared as on the design of the player. OTP is also called RSDL (reverse-spiral dual layer). The advantage of two layers is that long movies can use higher data rates for better quality than with a single layer. See 1.27 for more about layer changes.

There are various ways to recognize dual-layer discs: 1) the gold color, 2) a menu on the disc for selecting the widescreen or letterbox version, 3) two serial numbers on one side.

The DVD specification requires that players and drives read dual-layer discs. There are very few units that have problems with dual-layer discs--this is a design flaw and should be corrected for free by the manufacturer. Some discs are designed with a "seamless layer change" that technically goes beyond what the DVD spec allows. This causes problems on a few older players.

All players and drives also play double-sided discs if you flip them over. No manufacturer has announced a model that will play both sides. The added cost is hard to justify since discs can hold over 4 hours of video on one side by using two layers. (Early discs used two sides because dual-layer production was not widely supported. This is no longer a problem.) Pioneer LD/DVD players can play both sides of an LD, but not a DVD. (See 2.12 for note on reading both sides simultaneously.)

[1.19] Is DVD-Video a worldwide standard? Does it work with NTSC, PAL, and SECAM?

The MPEG video on DVD is stored in digital format, but it's formatted for one of two mutually incompatible television systems: 525/60 (NTSC) or 625/50 (PAL/SECAM). Therefore, there are two kinds of DVDs: NTSC DVDs and PAL DVDs. Some players only play NTSC discs, others play PAL and NTSC discs. Discs are also coded for different regions of the world (see 1.10).

All DVD players sold in PAL countries play both kinds of discs. These multi-standard players partially convert NTSC to a 60-Hz PAL (4.43 NTSC) signal. The player uses the PAL 4.43-MHz color subcarrier encoding format but keeps the 525/60 NTSC scanning rate. Most modern PAL TVs can handle this "pseudo-PAL" signal. A few multi-standard PAL players output true 3.58 NTSC from NTSC discs, which requires an NTSC TV or a multi-standard TV. Some players have a switch to choose 60-Hz PAL or true NTSC output when playing NTSC discs. There are a few standards-converting PAL players that convert from a NTSC disc to standard PAL output. Proper standards conversion requires expensive hardware to handle scaling, temporal conversion, and object motion analysis. Because the quality of conversion in DVD players is poor, using 60-Hz PAL output with a compatible TV provides a better picture. (Sound is not affected by video conversion.)

Most NTSC players can't play PAL discs. A very small number of NTSC players (such as Apex and SMC) can convert PAL to NTSC. External converter boxes are also available, such as the Emerson EVC1595 ($350). High-quality converters are available at TenLab and Snell and Wilcox.

There are three differences between discs intended for playback on different TV systems: picture size and pixel aspect ratio (720x480 vs. 720x576), display frame rate (29.97 vs. 25), and surround audio options (Dolby Digital vs. MPEG audio). (See 3.4 and 3.6 for details.) Video from film is usually encoded at 24 frames/sec but is preformatted for one of the two display rates. Movies formatted for PAL display are usually sped up by 4% at playback, so the audio must be adjusted accordingly before being encoded. All PAL DVD players can play Dolby Digital audio tracks, but not all NTSC players can play MPEG audio tracks. PAL and SECAM share the same scanning format, so discs are the same for both systems. The only difference is that SECAM players output the color signal in the format required by SECAM TVs. Note that modern TVs in most SECAM countries can also read PAL signals, so you can use a player that only has PAL output. The only case in which you need a player with SECAM output is for older SECAM-only TVs (and you'll probably need a SECAM RF connection, see 3.1).

A producer can choose to put 525/60 NTSC video on one side of the disc and 625/50 PAL on the other. Most studios put Dolby Digital audio tracks on their PAL discs instead of MPEG audio tracks. 

There are actually three types of DVD players if you count computers. Most DVD PC software and hardware can play both NTSC and PAL video and both Dolby Digital and MPEG audio. Some PCs can only display the converted video on the computer monitor, but others can output it as a video signal for a TV.

Bottom line: NTSC discs (with Dolby Digital audio) play on over 95% of DVD installations worldwide. PAL discs play on very few players outside of PAL countries. (This is irrespective of regions -- see 1.10.)

[1.20] What about animation on DVD? Doesn't it compress poorly?

Some people claim that animation, especially hand-drawn cell animation such as cartoons and anime, does not compress well with MPEG-2 or even ends up larger than the original. Other people claim that animation is simple so it compresses better. Neither is true.

Supposedly the "jitter" between frames caused by differences in the drawings or in their alignment causes problems. An animation expert at Disney pointed out that this doesn't happen with modern animation techniques. And even if it did, the motion estimation feature of MPEG-2 would compensate for it.

Because of the way MPEG-2 breaks a picture into blocks and transforms them into frequency information it can have a problem with the sharp edges common in animation. This loss of high-frequency information can show up as "ringing" or blurry spots along edges (called the Gibbs effect). However, at the data rates commonly used for DVD this problem does not occur.

[1.21] Why do some discs require side flipping? Can't DVDs hold four hours per side?

Even though DVD's dual-layer technology (see 3.3) allows over four hours of continuous playback from a single side, some movies are split over two sides of a disc, requiring that the disc be flipped partway through. Most "flipper" discs exist because of producers who are too lazy to optimize the compression or make a dual-layer disc. Better picture quality is a cheap excuse for increasing the data rate; in many cases the video will look better if carefully encoded at a lower bit rate. Lack of dual-layer production capability is also a lame excuse; in 1997 very few DVD plants could make dual-layer discs, but this is no longer the case. No players can automatically switch sides, but it's not needed since most movies less than 4 hours long can easily fit on one dual-layer (RSDL) side.

There is a list of "flipper" discs in the Film Vault at DVD Review. Note: A flipper is not the same as a disc with a widescreen version on one side and a pan & scan version or supplements on the other. Please send additions to info@dvdreview.com. (The list has gotten too long to keep in this FAQ.)

[1.22] Why is the picture squished, making things look too skinny?

Answer: RTFM. You are watching an anamorphic picture intended for display only on a widescreen TV. (See 3.5 for technical details). You need to go into the player's setup menu and tell it you have a standard 4:3 TV, not a widescreen 16:9 TV. It will then automatically letterbox the picture so you can see the full width at the proper proportions.

In some cases you can change the aspect ratio as the disc is playing (by pressing the "aspect" button on the remote control). On most players you have to stop the disc before you can change aspect. Some discs are labeled with widescreen on one side and standard on the other. In order to watch the fullscreen version you must flip the disc over.

See 1.38 for more on letterboxing.

[1.23] Do all videos use Dolby Digital (AC-3)? Do they all have 5.1 channels?

Most DVD-Video discs contain Dolby Digital soundtracks. However, it's not required. Some discs, especially those containing only audio, have PCM tracks. It's also possible for a 625/50 (PAL) disc to contain only MPEG audio, but so far MPEG audio is not widely used.

Don't assume that the "Dolby Digital" label is a guarantee of 5.1 channels. A Dolby Digital soundtrack can be mono, dual mono, stereo, Dolby Surround stereo, etc. For example, Blazing Saddles and Caddyshack are mono movies, so the Dolby Digital soundtrack on these DVDs has only one channel. Some DVD packaging has small lettering or icons under the Dolby Digital logo that indicates the channel configuration. In some cases, there is more than one Dolby Digital version of a soundtrack: a 5.1-channel track and a track specially remixed for stereo Dolby Surround. It's perfectly normal for your DVD player to indicate playback of a Dolby Digital audio track while your receiver indicates Dolby Surround: it means that the disc contains a two-channel Dolby Surround signal encoded in Dolby Digital format.

See 3.6 for more audio details.

[1.24] Can DVDs have laser rot?

Laserdiscs are subject to what's commonly called laser rot: the deterioration of the aluminum layer due to oxidation or other chemical change. This often results from the use of insufficiently pure aluminum during replication, but can be exacerbated by mechanical shear stress due to bending, warping or thermal cycles (the large size of laserdiscs makes them flexible, so that movement along the bond between layers can break the seal). Deterioration of the data layer can be caused by chemical contaminants or gasses in the glue, or by moisture that penetrates the acrylic substrates.

Like laserdiscs, DVDs are made of two platters glued together, but DVDs are more rigid and use newer adhesives. DVDs are molded from polycarbonate, which absorbs about ten times less moisture than the slightly hygroscopic acrylic (PMMA) used for laserdiscs.

It's too early to know for sure, but DVDs will probably have few laser rot problems. There have been reports of a few discs going bad, possibly due to poor adhesive, chemical reactions, or oxidation of the aluminum layer. See www.mindspring.com/~yerington/.

[1.25] Which titles are pan & scan only? Why?

Some titles are available only in pan & scan because there was no letterbox or anamorphic transfer made from film. (See 3.5 for more info on pan & scan and anamorphic formats.) Since transfers cost $50,000 to $100,000, studios may not think a new transfer is justified. In some cases the original film or rights to it are no longer available for a new transfer. In the case of old movies, they were shot full frame in the 1.37 "academy" aspect ratio so there can be no widescreen version. Video shot with TV cameras, such as music concerts, is already in 4:3 format.

The list of pan & scan only titles has gotten too big to keep here. You can get a list from the Film Vault at DVD Review, or from Internet Movie Database (which also includes discs with both widescreen and pan & scan versions).

[1.26] How do I make the subtitles on my Pioneer player go away?

On the remote control, press Subtitle, then either Clear or 0 (zero). No need to use the menus.

[1.27] What is a layer change? Where is it on specific discs?

Some movies, especially those over two hours long or encoded at a high data rate, are spread across two layers on one side of the disc. When the player changes to the second layer, the video and audio may freeze for a moment. The length of the pause depends on the player and on the layout of the disc. The pause is not a defect in the player or the disc. See 1.18 for details.

There is a list of layer switch points in the Film Vault at DVD Review. Please send new times to info@dvdreview.com. (The list has gotten too long to keep in this FAQ.)

[1.28] The disc says Dolby Digital. Why do I get 2-channel surround audio?

Some discs (many from Columbia TriStar) have 2-channel Dolby Surround audio (or plain stereo) on track one and 5.1-channel audio on track two. Since some studios create separate sound mixes optimized for Dolby Surround or stereo, and they feel the default track should match the majority of sound systems in use. Unless you specifically select the 5.1-channel track (with the audio button on the remote or with the on-screen menu) the player will play the default 2-channel track. (Note: Some players such as the Sony 3000 have a feature to automatically select the first 5.1 track.)

Dolby Digital doesn't necessarily mean 5.1 channels. See 3.6.

[1.29] Why doesn't the repeat A-B feature work on some discs?

Almost all features of DVD such as search, pause, and scan can be disabled by the disc, which can prevent the operation the player needs to back up and repeat a segment. If the player uses time search to repeat a segment, then a disc with fancy non-sequential title organization may also block the repeat feature. In many cases the authors don't even realize they have prevented the use of this feature.

[1.30] What's the difference between first, second, and third generation DVD?

There is no meaningful answer to this question, since you'll get a different response from everyone you ask. The terms "2nd generation" and "3rd generation," and so on refer both to DVD-Video players and to DVD-ROM drives. In general, they simply mean newer versions of DVD playback devices. The terms haven't been used (yet) to refer to DVD products that can record, play video games, or so on.

According to some people, second-generation DVD players came out in the fall of 1997 and third-generation players are those that came out in the beginning of 1998. According to others, the second generation of DVD will be HD players (see 2.12) that won't come out until 2003 or so. There are many conflicting variations between these extremes, including the viewpoint that DTS-compatible players or Divx players or progressive-scan players or 10-bit video players or players that can play The Matrix constitute the second, third, or fourth generation.

Things are a little more clear cut on the PC side, where second generation (DVD II) usually means 2x DVD-ROM drives that can read CD-Rs, and third generation (DVD III) usually means 5x (or sometimes 2x or 4.8x or 6x) DVD-ROM drives, a few of which can read DVD-RAMs, and some of which are RPC2 format. Some people refer to RPC2 drives or 10x drives as fourth generation. See section 4.2 for more speed info. See section 1.10 for RPC2 explanation.

[1.31] What's a hybrid DVD?

Do you really want the answer to this one? Ok, you asked for it...

  1. A disc that works in both DVD-Video players and DVD-ROM PCs. (The most common use of the term hybrid, but more accurately called an enhanced DVD)
  2. A DVD-ROM disc that runs on Windows and Mac OS computers. (More accurately called a cross-platform DVD.)
  3. A DVD-ROM or DVD-Video disc that also contains Web content for connecting to the Internet. (More accurately called a WebDVD or Web-connected DVD.)
  4. A disc that contains both DVD-Video and DVD-Audio content. (More accurately called a universal or AV DVD.)
  5. A disc with two layers, one that can be read in DVD players and one that can be read in CD players. (More accurately called a legacy or CD-compatible disc.) There are at least three variations of this hybrid (none were commercially available as of 12/99):
    1. A 0.9 to 1.2 mm CD substrate bonded to the back of a 0.6 mm DVD substrate. One side can be read by CD players, the other side by DVD players. The resulting disc is 0.6 mm thicker than a standard CD or DVD, which can cause problems in players with tight tolerances, such as portables. Sonopress, the first company to announce this type, calls it DVDPlus. It's colloquially known as a "fat" disc. There's a variation in which an 8-cm data area is embedded in a 12-cm substrate so that a label can be printed on the outer ring. 
    2. A 0.6 mm CD substrate bonded to a semitransparent 0.6 mm DVD substrate. Both layers are read from the same side, with the CD player being required to read through the semitransparent DVD layer, causing problems with some CD players.
    3. A 0.6 mm CD substrate, with a special refractive coating that causes a 1.2 mm focal depth, bonded to the back of a 0.6 mm DVD substrate. One side can be read by CD players, the other side by DVD players.
  6. A disc with two layers, one containing pressed (DVD-ROM) data and one containing rewritable (DVD-RAM, etc.) media for recording and re-recording. (More accurately called a DVD-PROM,  mixed-media, or rewritable sandwich disc.)
  7. A disc with two layers on one side and one layer on the other. (More accurately called a DVD-14.)
  8. A disc with an embedded memory chip for storing custom usage data and access codes. (More accurately called a chipped DVD.)

Did I miss any?

[1.32] What's the deal with DTS and DVD?

Digital Theater Systems Digital Surround is an audio encoding format similar to Dolby Digital. It requires a decoder, either in the player or in an external receiver. See 3.6.2 for technical details. Some people claim that because of its lower compression level DTS sounds better than Dolby Digital. Others claim there is no meaningfully perceptible difference, especially at the typical data rate of 768 kbps, which is 60% more than Dolby Digital. Because of the many variances in production, mixing, decoding, and reference levels, it's almost impossible to accurately compare the two formats (DTS usually produces a higher volume level, causing it to sound better in casual comparisons).

DTS originally did all encoding in house, but as of October 1999 DTS encoders are available for purchase. DTS titles are generally considered to be specialty items intended for audio enthusiasts. Most DTS are also be available in a Dolby Digital-only version.

DTS is an optional format on DVD. Contrary to uninformed claims, the DVD specification has included an ID code for DTS since 1996 (before the spec was even finalized). Because DTS was slow in releasing encoders and test discs, players made before mid 1998 (and many since) ignore DTS tracks. A few demo discs were created in 1997 by embedding DTS data into a PCM track (the same technique used with CDs and laserdiscs), and these are the only DTS DVD discs that work on all players. New DTS-compatible players arrived in mid 1998, but theatrical DTS discs using the proper DTS audio stream ID did not appear until January 7, 1999 (they were originally scheduled to arrive in time for Christmas 1997). Mulan, a direct-to-video animation (not the Disney movie) with DTS soundtrack appeared in November 1998. DTS-compatible players carry an official "DTS Digital Out" logo.

Dolby Digital or PCM audio are required on 525/60 (NTSC) discs, and since both PCM and DTS together don't usually leave enough room for quality video encoding of a full-length movie, essentially every disc with a DTS soundtrack also carries a Dolby Digital soundtrack. This means that all DTS discs will work in all DVD players, but a DTS-compatible player and a DTS decoder are required to play the DTS soundtrack. DTS audio CDs work on all DVD players, since the DTS data is encapsulated into standard PCM tracks that are passed untouched to the digital audio output.

[1.33] Why is the picture black and white?

You are probably trying to play an NTSC disc in a PAL player, but your PAL TV is not able to handle the signal. If your player has a switch or on-screen setting to select the output format for NTSC discs, choosing PAL (60-Hz) may solve the problem. See section 1.19 for more information.

Or you may have connected one of the component outputs (Y, R-Y, or B-Y) of your DVD player to the composite input of your TV. See section 3.2 for hookup details. 

[1.34] Why are both sides fullscreen when one side is supposed to be widescreen?

Many DVD's are labeled as having widescreen (16:9) format video on one side and standard (4:3) on the other. If you think both sides are the same, you're probably seeing uncompressed 16:9 on the widescreen side. It seems to be 4:3 pan & scan, but if you look carefully you'll discover that the picture is horizontally compressed. The problem is that your player has been set for a widescreen TV. See 1.22 for details.

[1.35] Why are the audio and video out of sync?

There have been numerous reports of "lip sync" problems, where the audio lags slightly behind the video, and even reports of the audio coming before the video. Perception of a sync problem is highly subjective--some people are bothered by it while others can't discern it at all. Problems have been reported on a variety of players (notably the Pioneer 414 and 717 models, possibly all Pioneer models, some Sony models including the 500 series and the PS2, new Toshiba models including the 3109, and some PC decoder cards). Certain discs are also more problematic (notably Lock, Stock, and Two Smoking Barrels; Lost In Space; TRON; The Parent Trap; and Austin Powers).

The cause of the sync problem is a complex interaction of as many as four factors

  1. Improper sync in audio/video encoding or DVD-Video formatting.
  2. Poor sync during film production or editing (especially post-dubbing or looping).
  3. Loose sync tolerances in the player.
  4. Delay in the external decoder/receiver.

Factor 1 or 2 usually must be present in order for factor 3 or 4 to become apparent. Some discs with severe sync problems have been reissued after being re-encoded to fix the problem. In some cases, the sync problem in players can be fixed by pausing or stopping playback and then restarting, or by turning the player off, waiting a few seconds, then turning it back on.

A good way to test your player is to simultaneously listen to the analog and digital outputs (play the digital output through your stereo and the analog output through your TV). If the audio echoes or sounds hollow, then the player is delaying the signal and is thus the main cause of the sync problem.

Unfortunately, there is no simple answer and no simple fix. More complaints from customers should motivate manufacturers to take the problem more seriously and correct it in future players or with firmware upgrades. Pioneer originally stated that altering the audio-visual synchronization of their players "to compensate for the software quality would dramatically compromise the picture performance." Since then Pioneer has fixed the problem on its new players. If you have an older model, check with Pioneer about an upgrade.

For many more details, see Michael D's Pioneer Audio Sync page.

[1.36] Why does the picture alternate between light and dark?

You are seeing the effects of Macrovision copy protection (see 1.11), probably because you are running your DVD player through your VCR or VCR/TV combo (see 3.2.1).

[1.37] How do I find "Easter eggs" and other hidden features?

Some DVD movies contain hidden features, often called "Easter eggs." These are extra screens or video clips hidden in the disc by the developers. For example, Dark City includes scenes from Lost in Space and the Twin Peaks movie buried in the biography pages of William Hurt and Keifer Sutherland. There's also an amusing "Shell Beach" game entwined throughout the menus. On Mallrats, perhaps indicating that DVD has already become too postmodern for its own good, there's a hidden clip of the director telling you to stop looking for Easter eggs and do something useful.

It's more fun to search for hidden features on your own, but if you need some help, the best list is at DVD Review.

[1.38] How do I get rid of the black bars at the top and bottom?

The black bars are part of the letterbox process (see 3.5), and in many cases you can't get rid of them. If you set the display option in your player to pan & scan (sometimes called fullscreen or 4:3) instead of letterbox, it won't do you much good since no DVD movies have been released with this feature enabled. If you set the player to 16:9 widescreen output it will make the bars smaller, but you will get a tall, stretched picture unless you have a widescreen TV.

In some cases, there may be both a fullscreen and a letterbox version of the movie on the same disc, with a variety of ways to get to the fullscreen version (usually only one works, so you may have to try all three):

  1. Check the other side of the disc (if it's two-sided)
  2. Look for a fullscreen choice in the main menu
  3. Use the "aspect" button on the remote control

DVD was designed to make movies look as good as possible on TV. Since most movies are wider than most TVs, letterboxing preserves the format of the theatrical presentation. (Nobody complains that the top and bottom of the picture are cut off in theaters.) DVD is ready for TVs of the future, which are widescreen. For these and other reasons, many movies on DVD are only available in widescreen format.

About two thirds of widescreen movies are filmed at 1.85 ("flat") aspect ratio or less. In this case, the actual size of the image on your TV is the same for a letterbox version and a full-frame version, unless the pan & scan technique is used to zoom in (which cuts off part of the picture). In other words, the picture is the same size, with extra areas visible at the top and bottom in the fullscreen version. In more other words, letterboxing covers over the part of the picture that was also covered in the theater, or it allows the entire widescreen picture to be visible for movies wider than 1.85, in which case the letterboxed picture is smaller and has less detail than a pan & scan version would.

For a detailed explanation of why most movie fans prefer letterboxing, see the Letterbox/Widescreen Advocacy Page. For an explanation of anamorphic widescreen and links to more information and examples on other Web sites, see 3.5.

The best solution to this entire mess might be the FlikFX Digital Recomposition System, "the greatest advance in entertainment in 57 years."

[1.39] How should I clean and care for DVDs?

Since DVDs are read by a laser, they are resistant—to a point—to fingerprints, dust, smudges, and scratches (see 1.15 for more info). However, surface contaminants and scratches can cause data errors. On a video player, the effect of data errors ranges from minor video artifacts to frame skipping to complete unplayability. So it's a good idea to take care of your discs. In general treat them the same way as you would a CD.

Your player can't be harmed by a scratched or dirty disc, unless there are globs of nasty substances on it that might actually hit the lens. Still, it's best to keep your discs clean, which will also keep the inside of your player clean. Never attempt to play a cracked disc, as it could shatter and damage the player. It doesn't hurt to leave the disc in the player (even if it's paused and still spinning), but leaving it running unattended for days on end might not be a good idea.

In general, there's no need to clean the lens on your player, since the air moved by the rotating disc keeps it clean. However, if you commonly use a lens cleaning disc in your CD player, you may want to do the same with your DVD player. I recommend only using a cleaning disc designed for DVD players, since there are minor differences in lens positioning.

There is no need for periodic alignment of the pickup head. Sometimes the laser can drift out of alignment, especially after rough handling of the player, but this is not a regular maintenance item.

Care and feeding of DVDs

Handle only at the hub or outer edge. Don't touch the shiny surface with your popcorn-greasy fingers.

Store in a protective case when not in use. Do not bend the disc when taking it out of the case, and be careful not to scratch the disc when placing it in the case or in the player tray.

Make certain the disc is properly seated in the player tray before you close it.

Keep away from radiators/heaters, hot equipment surfaces, direct sunlight (near a window or in a car during hot weather), pets, small children, and other destructive forces. Magnetic fields have no effect on DVDs. The DVD specification recommends that discs be stored at a temperature between -20 to 50 °C (-4 to 122 °F) with less than 15 °C (27 °F) variation per hour, at relative humidity of 5% to 90%.

Coloring the outside edge of a DVD with a green marker (or any other color) makes no difference in video or audio quality. Data is read based on pit interference at 1/4 of the laser wavelength, a distance of less than 165 nanometers. A bit of dye that on average is more than 3 million times farther away is not going to affect anything.

Cleaning and repairing DVDs

If you notice problems when playing a disc, you may be able to correct them with a simple cleaning.

If you continue to have problems after cleaning the disc, you may need to attempt to repair one or more scratches. Sometimes even hairline scratches can cause errors if they just happen to cover an entire ECC block. Examine the disc, keeping in mind that the laser reads from the bottom. There are essentially two methods of repairing scratches: 1) fill or coat the scratch with an optical material; 2) polish down the scratch. There are many commercial products that do one or both of these, or you may wish to buy polishing compounds or toothpaste and do it yourself. The trick is to polish out the scratch without causing new ones. A mess of small polishing scratches can cause more damage than a big scratch. As with cleaning, polish only in the radial direction.

Libraries, rental shops, and other venues that need to clean a lot discs may want to invest in a commercial polishing machine that can restore a disc to pristine condition after an amazing amount of abuse. Keep in mind that the data layer on a DVD is only half as deep as on a CD, so a DVD can only be re-polished about half as many times.

[1.40] What's a progressive DVD player?

A progressive-scan DVD player converts the interlaced (480i) video from DVD into progressive (480p) format for connection to a progressive display (31.5 kHz or higher). Progressive players work with all standard DVD titles, but look best with film source. The result is a significant increase in perceived vertical resolution, for a more detailed and film-like picture.

There's enormous confusion about whether DVD video is progressive or interlaced. Here's the one true answer: Progressive-source video (such as from film) is usually encoded on DVD as interlaced field pairs that can be re-interleaved by a progressive player to recreate the original progressive video. See 3.8 for further explanation of interlaced and progressive scanning.

You must use a progressive-scan display in order to get the full benefit of a progressive-scan player. However, all progressive players also include interlaced outputs, so you can buy one to use with a standard TV until you upgrade to a progressive TV. (You may have to use a switch on the back of the player to set it to interlaced output.)

Toshiba developed the first progressive-scan player (SD5109, $800) in mid 1998, but didn't release it until fall of 1999 because of copy protection concerns. Panasonic also released a progressive-scan player (DVD-H1000, $3000) in fall of 1999. Many manufacturers have released progressive models since then. It's also possible to buy an external line multiplier to convert the output of a standard DVD player to progressive scanning. All DVD computers are progressive players, since the video is displayed on a progressive monitor, but quality varies a lot. (See 4.1 and 2.12.)

Converting interlaced DVD video to progressive video involves much more than putting film frames back together. There are essentially two ways to convert from interlaced to progressive:
1- Re-interleaving (also called weave). If the original video is from a progressive source, such as film, the two fields can be recombined into a single frame.
2- Line doubling (also called bob). If the original video is from an interlaced source, simply combining two fields will cause motion artifacts (the effect is reminiscent of a zipper), so each line of a single field is repeated twice to form a frame. Better line doublers use interpolation to produce new lines that are a combination of the lines above and below. The term line doubler is vague, since cheap line doublers only bob, while expensive line doublers (those that contain digital signal processors) can also weave.
(3- There's actually a third way, called field-adaptive de-interlacing, which examines individual pixels across three or more fields and selectively weaves or bobs regions of the picture as appropriate. Most systems that do this well cost $10,000 and up, so it will be a while before we see it in consumer DVD players.)
(4- And there's also a fourth way, called motion-adaptive de-interlacing, which examines MPEG-2 motion vectors or does massive image processing to identify moving objects in order to selectively weave or bob regions of the picture as appropriate. Most systems that do this well cost $50,000 and up (aside from the cool but defunct Chromatic Mpact2 chip).

There are three common kinds of de-interlacing systems:
1- Integrated. This is usually best, where the de-interlacer is integrated with the MPEG-2 decoder so that it can read MPEG-2 flags and analyze the encoded video to determine when to bob and when to weave. Most DVD computers use this method.
2- Internal. The digital video from the MPEG-2 decoder is passed to a separate deinterlacing chip. The disadvantage is that MPEG-2 flags and motion vectors may no longer available to help the de-interlacer determine the original format and cadence. (Some internal chips receive the repeat_first_field and top_field_first flags passed from the decoder, but not the progressive_scan flag.)
3- External. Analog video from the DVD player is passed to a separate de-interlacer (line multiplier) or to a display with a built-in de-interlacer. In this case, the video quality is slightly degraded from being converted to analog, back to digital, and often back again to analog. However, for high-end projection systems, a separate line multiplier (which scales the video and interpolates to a variety of scanning rates) may achieve the best results.

Most progressive DVD players use an internal Genesis gmVLX1A de-interlacing chip. The Princeton PVD-5000 uses a Sigma Designs decoder with integrated de-interlacing. The JVC XV-D723GD uses a custom decoder with integrated de-interlacing. Toshiba's "Super Digital Progressive" players and the Panasonic HD-1000 use 4:4:4 chroma oversampling, which provides a slight quality boost from DVD's native 4:2:0 format. Add-on internal de-interlacers such as the Cinematrix and MSB Progressive Plus are available to convert existing players to progressive-scan output. Faroudja, Silicon Image (DVDO), and Videon (Omega) line multipliers are examples of external de-interlacers.

A progressive DVD player has to determine whether the video should be line-doubled or re-interleaved. When re-interleaving film-source video, the player also has to deal with the difference between film frame rate (24 Hz) and TV frame rate (30 Hz). Since the 2-3 pulldown trick can't be used to spread film frames across video fields, there are worse motion artifacts than with interleaved video. However, the increase in resolvable resolution more than makes up for it. Advanced progressive players such as the Princeton PVD-5000 and DVD computers can get around the problem by displaying at multiples of 24 Hz such as 72 Hz, 96 Hz, and so on.

A progressive player also has to deal with problems such as video that doesn't have clean cadence (as when it's edited after being converted to interlaced video, when bad fields are removed during encoding, when the video is speed-shifted to match the audio track, and so on). Another problem is that many DVDs are encoded with incorrect MPEG-2 flags, so the re-interleaver has to recognize and deal with pathological cases. In some instances it's practically impossible to determine if a sequence is 30-frame interlaced video or 30-frame progressive video. For example, the documentary on Apollo 13 is interlaced video encoded as if it were progressive. Other examples of improper encoding are Titanic, Austin Powers, Fargo, More Tales of the City, the Galaxy Quest theatrical trailer, and The Big Lebowski making-of featurette.

A growing problem is that many TVs with progressive input don't allow the aspect ratio to be changed. When a non-anamorphic signal is sent to these TVs, they stretch it out! Before you buy an HDTV, make sure that it allows aspect ratio adjustment on progressive input.

Just as early DVD computers did a poor job of progressive-scan display of DVDs, the first generation of progressive consumer players are also a bit disappointing. But as techniques improve, and as DVD producers become more aware of the steps they must take to ensure good progressive display, and as more progressive displays appear in homes, the experience will undoubtedly improve, bringing home theaters closer to real theaters.

For more on progressive video and DVD, see part 5 and player ratings in the excellent DVD Benchmark series at Secrets of Home Theater and High Fidelity.

[1.41] Why doesn't disc X work in player Y?

The DVD specification is complex and open to interpretation. DVD-Video title authoring is also very complex. As with any new technology, there are compatibility problems here and there. The DVD-Video standard has not changed substantially since it was finalized in 1996, but many players don't properly support it. Discs have become more complex as authoring tools improve, so recent discs often uncover engineering flaws in players. Some discs behave strangely or won't play at all in certain players. In some cases, manufacturers can fix the problem with an upgrade to the player (see 1.47). In other cases, disc producers need to re-author the title to correct an authoring problem or to work around a player defect. Problems can also occur because of damaged or defective discs or because of a defective player.

If you have problems playing a disc, try the following:

  1. Check the list below to see if it's a reported problem. Also check the list of problem discs in DVD Review's Film Vault and at InterActual's PCFriendly tech support page. Try a newsgroup search at Deja.
  2. Try playing the disc a few more times. If you don't get the exact same problem every time, then it's probably a defective or damaged disc. Make sure the disc isn't dirty or scratched (see 1.39).
  3. Try the disc in a different player. (Visit a friend or a nearby player retailer.) The problem is usually the player, not the disc. If the disc plays properly in a different player, contact the manufacturer of your player for a firmware upgrade. Or, if you bought the player recently, you may wish to return it for a different model.
  4. Try a different copy of the disc. If the problem doesn't recur, it indicates that your first copy was probably damaged or defective. If more than one copy of the disc has problems in more than one player, then it may be a misauthored disc. Contact the distributor or the studio.

For other DVD and home theater problems, try Doc DVD, or DVD Digest's Tech Support Zone. Also check the PCFriendly tech support site for info about players that have problems with some enhanced discs. If you have a Samsung 709, see the Samsung 709 FAQ. For troubleshooting DVD on computers, see 4.6. The Dell Inspiron 7000 DVD Movie List has Inspiron-specific problems.

Below are problems reported by readers of this FAQ. The FAQ author has not verified these claims and takes no responsibility for their accuracy. Please report other confirmed problems. 

Title Player Problem Solution
various Polygram titles early Toshiba and Magnavox models won't load or freezes upgrade available from Toshiba service centers
various Central Park Media (anime) titles similar problems as The Matrix
RCE titles (see 1.10) Fisher DVDS-1000,  Sanyo Model DVD5100 world map and "only plays on non-modified players" message contact tech Sanyo/Fisher support for workaround
The Abyss, SE early Toshiba models disc 2 won't load or freezes upgrade available from Toshiba service centers
many cheap players  repeats scenes player doesn't properly handle seamless branching, get upgrade from manufacturer
Apex AD-600A scenes play twice check with Apex for upgrade
American Beauty (Awards Edition) Toshiba SD-3108, Philips DVD805 won't load get upgrade from manufacturer service center (Toshiba firmware 3.30 or newer)
American Pie Philips 940 freezes at layer change (1:17:09)  
Any Given Sunday Pioneer Elite DVL90 won't load  
Arlington Road see Cruel Intentions
Armageddon Panasonic A115-U and A120-U won't load unplug player with disc inserted, plug in, turn on
Avenger's TV series (A&E) Toshiba SD-3108 locks up player upgrade available from Toshiba service centers
Philips 930, 935 won't load check with Philips for firmware upgrade
Bats Apex AD 600A wont' load check with Apex for upgrade
Big Trouble in Little China Special Edition Panasonic SC-DK3 won't load unplug player with disc inserted, plug in, turn on
The Blair Witch Project some Toshiba players doesn't play properly upgrade available from Toshiba service centers
Cruel Intentions some JVC and Yamaha error in first release messes up parental controls, causing other discs to not play reset