DVD AND HD DISC PLAYERS:
Only a couple years after the DVD format was launched in March 1997, DVD had become the fastest growing new technology ever topping even VHS or the CD. The DVD video format is the successor to both the LaserDisc and the audio Compact Disc, combining the best qualities of both formats and adding a few new benefits. Using a 5" optical disc that looks outwardly identical to a CD, DVD's store anywhere from 4.7 gigabytes (GB) to 18 GB (compared to a CD's capacity of 650 or 700 MB -- 0.65 GB or 0.7 GB). For a detailed analysis of DVD, try Jim Taylor's DVD FAQ, but the next paragraph will give you a brief summary. Once we get that good news out of the way, I'll discuss the latest 5" optical discs that have brought about another dreaded format war.
We'll start all of this off with a detailed look at the DVD format. First, the DVD disc itself. DVD's are simply optical data discs, and as such can store data in many different ways. These can include DVD-video (which is what we will be concerned with here), DVD-ROM for your computer, and DVD-audio (a high-resolution audio disc format using the DVD that was one-half of a small format war). A DVD can be configured in several different ways: one or two sides, and one or two layers on a side. Early discs were single-layer, because of the manufacturing challenges involved in mass production of dual-layer discs. A single layer disc can hold 4.7 GB, and is sometimes referred to as a DVD-5 (for approximately 5 GB). A dual-sided single layer disc can hold 4.7 GB on each side. These are sometimes called DVD-10 (for approximately 10 GB). Dual-sided discs were used in early DVD releases for particularly long movies, in which case the viewer had to get up and flip the disc over to see the end of the movie (these are generally referred to as "flipper" discs). Dual-sided discs can also be used to store different versions of the movie on different sides (widescreen on one side, pan-and-scan on the other), or to store the movie on one side and extra features on the other. Dual-layer discs have two layers of data stored on one side, requiring the player to adjust it's laser to read from one or the other. For these discs, the capacity per layer is less, at somewhere around 4.3 GB per layer or 8.6 GB overall; these are often referred to as DVD-9 discs. For longer movies, it is possible to use "RSDL" (reverse spiral dual layer) encoding to spread a movie across both layers and play it back without interruption. In other cases, one layer can be used for a movie and the other for extra features. Once the bugs were worked out of the manufacturing process for DVD-9 discs, it became widely used as a way to avoid "flipper" discs. Lastly, it is possible (albeit expensive) to produce dual layer, dual sided discs (DVD-18), which can store 8.6 GB per side. It took several years for manufacturers to be able to successfully mass produce DVD-18 discs, and in many cases they even now choose to use two DVD-9 discs instead (Terminator 2: Ultimate Edition was one of the first DVD-18 titles released, but production problems forced them to produce a batch of two-disc DVD-9 sets to meet the demand of the original release). Lastly, DVD's look identical to CD's, so to help avoid confusion the packaging for DVD is different from the traditional CD jewel case. The two main packages originally were the snapper case (a rather cheap-feeling cardboard and plastic case produced by a company owned by Warner Brothers) and the keepcase (an all-plastic case with a clear plastic cover that can hold the package graphics), but the snapper case eventually died off due in part to consumer hatred. Several different companies manufacture keepcases, but the most common two are the Alpha and Amaray, both of which are made by the same manufacturer. The Alpha has a center clasp that resembles the "yin and yang" symbol, and the Amaray has a more solid hub.
That covers the discs themselves, but what about the information? DVD's store audio and video information in a compressed digital format. The video is compressed using MPEG codecs, and the audio is generally encoded in one of a few digital formats. DVD offers 480 lines of video data; this is one of the principle reasons that DVD looks better than VHS, which is restricted to 250 lines of resolution. The typical audio formats offered by DVD are Dolby Digital (2.0 or 5.1) and DTS. Dolby Digital is the standard, although the audio may use only one or two channels (mono or stereo) or 4.1 or 5.1 (surround formats with stereo, a discrete center channel, mono surround or discrete left and right surrounds, and a low frequency LFE channel) channels. DTS is a 5.1 channel format that provides more bandwidth for the audio, although it requires more space on the disc. DTS has slowly become more and more common, and many people feel that it provides superior sound to Dolby Digital. In addition to this, DVD allows for multiple audio tracks, so a single disc can have multiple languages or commentary tracks available. In order to get full benefit from these surround formats, it is necessary to either connect the DVD player to a Dolby Digital/DTS-decoder-equipped receiver or pre-amp/processor using a digital audio cable or to rely on a decoder in the DVD player and connect six separate analogs cables to a receiver or pre-amp. Players with built-in decoders are available, but they are typically more expensive and still require a receiver capable of accepting a six-channel analog input. If none of these are available, the DVD player's two-channel analog audio outputs can be used; this signal can be decoded using a Dolby Pro-Logic decoder if one is available or it can be connected directly to a TV. The video options are in some ways less complicated. Output can be by composite, S-video, component video, or (in a few cases) DVI or HDMI connections as described in the Display section. If none of those are available at the TV, an RF modulator ($30 at Radio Shack) can be used to connect the DVD player to a TV that lacks any of these inputs.
Perhaps because DVD was seen as the successor to LaserDisc (which was a format that never expanded beyond the niche market of consumers who are often called "early adopters" people who embrace new technology without waiting for it to become established), there was always a strong consumer interest in preserving movies' original aspect ratio (OAR) on DVD. This meant that the format could expect to see many discs that contained widescreen video with black bars "letterboxing" the image at the top and bottom. To allow the format to make maximum use of its resolution, the DVD format includes provisions for video to be stored in anamorphic form (sometimes called 16x9 enhanced). The video is formatted as a 16x9 image (or a 1.78:1 ratio), with much smaller black bars at the top and bottom to preserve the original aspect ratio of 1.85:1 or 2.35:1. Players that are configured to operate with a traditional 4:3 display squeeze the source video into the middle of the screen and generate black bars at the top and bottom to allow the image to display correctly. When the players are connected to a 16x9 display, however, the player is able to make maximum use of its native resolution by having as few lines as possible wasted on black bars. It is this maximized use of the video resolution (which can add up to 33% more lines available for image data) that makes anamorphic video such a great benefit for the format. For more specific information on anamorphic video, check out Bill Hunt's Ultimate Guide to Anamorphic Widescreen DVD at The Digital Bits.
Since we're talking about making best use of DVD's native resolution, perhaps we should explain what that resolution is. The native video format for DVD is 480i (see the Terms and Technology or Displays sections for details on what that means). With the arrival of enhanced definition and high definition TV's in the late 1990's, there became interest in incorporating deinterlacing video processing into DVD players to allow them to output a progressive scan signal (or 480p). The concept of progressive scan video has been around since the inception of the DVD format, but it took several years for players capable of generating a progressive video output to reach the market. By 2003, however, progressive scan had become a standard feature for new DVD players at any price point. Viewing progressive scan video requires the use of component video connections and a display capable of supporting progressive video playback (in general, this means an HDTV-compatible display); owners of standard definition televisions can not make use of progressive scan playback. With a standard (interlaced) video signal, the display refreshes every 1/60 of a second, but each refresh only re-draws every other line; each individual line is refreshed 30 times in one second. With progressive scan, however, the display re-draws all of the lines at once each time it refreshes; each individual line is refreshed 60 times in one second. For comparison, film provides 24 individual frames every second (the difference between 24 and 60 requires some manipulation as well, which is often referred to as "2-3 pulldown" or "3:2 pulldown"). The end result of progressive scan video is that it eases the burden on our eyes of merging the stream of still images into a continuous video image, behaving more like a projected film in a theater. As a result, progressive scan video can provide a clearer and more life-like picture.
A logical successor to progressive scan video is video upscaling players that include scalars that can convert a DVD's 480i source to 720p or 1080i (the two principal HD resolutions). Typically, these players can only output these higher resolution images over digital video outputs (DVI or HDMI), although a handful of players have offered 720p and 1080i output over component video. By 2005, upscaling had become common on most higher-end players such as those from Denon, Yamaha, Pioneer, Panasonic, and others. It was a handful of less costly players that really put the approach on the map, however the Bravo D1 and D2 from V, Inc. (now Vizio), inexpensive players from Samsung and Zenith/LG, and an unlikely offering from OPPO Digital (the OPDV971H) that appeared in early 2005. For many people, these small but mighty players offer a great compromise between the untapped potential of their HDTV's and the HD format war between HD-DVD and Blu-ray (which we'll discuss in detail shortly).
One final note on DVD video has to be a mention of the "chroma bug" -- a problem common to many DVD players' MPEG decoders that existed for several years without being detected before being discovered and becoming general knowledge thanks to an article at Secrets of Home Theater and High Fidelity. It is described here, and is essentially a chroma upsampling error that generates horizontal streaks on brightly colored objects. The bug is very common in older players and is directly related to the decoder chip used. Some manufacturers escaped almost unscathed, including Panasonic. Others that were affected by the bug in at least some of their players included Sony, Toshiba, and Pioneer. The really cheap players seen in grocery store check-out lines may still suffer from the bug, but others will have typically resolved the problem.
Alongside all of this audio and video information are the "extra" features of DVD: navigation menus, commentary tracks, theatrical trailers, deleted scenes, documentaries, and DVD-ROM features like scripts, web links, games, and screen savers that must be accessed through a computer with a DVD-ROM drive. The navigation menus are a basic requirement of the format, a way to get access to the disc's content. In many cases, however, the menus can still be very interactive, with animated screens, video transitions between menu components, and hidden "easter egg" features. The rest are included on discs in some cases -- commentary tracks and trailers are fairly common. Expect "movie-only" discs to be just that: the movie and a menu to let you start playing it. Special editions will generally include some or all of the extras mentioned above.
A variation on the DVD format is DVD-Audio, a replacement for CD that uses DVD discs and a multi-channel audio format that offers greater audio quality than CD. Sony has released a competing format for the "CD-replacement" called Super Audio CD, or SACD. Both formats were developed in response to the decades-old complaint about CD's limitations in digitally storing and reproducing music. By changing the manner in which analog audio is converted to digital data, both formats allow for more lifelike audio reproduction; lossless compression and the inclusion of as many as six separate audio channels (as compared to CD's two channels) further differentiate the two "high resolution" formats from their 16-bit successor. There is a great deal of debate over which format is superior; both were seen as serious piracy concerns by the music industry, and therefore both were required to do all D/A conversion internally for several years and output their 5.1 signal in an analog format. The industry eventually developed and agreed on a standard digital output for DVD-Audio and SACD, but the development of this standard proceeded slowly in large part due to copy protection concerns raised by the RIAA. The interface selected for DVD-Audio and SACD was IEEE-1394, also known as FireWire or iLink. Development of the standard encryption used across the FireWire connection delayed the introduction of players and receivers using this connection so long that both formats had time to dwindle to niche status; FireWire is almost nonexistent in the market, and most consumers continue to rely on 5.1 analog audio connections for both formats. More recently, HDMI v1.1 allowed for the transmission of DVD-Audio signals and HDMI v1.2 allowed for the transmission of SACD (see my HDMI FAQ for more details about this). Some manufacturers have also introduced proprietary digital interfaces for DVD-Audio, SACD, or both. In general, though, most DVD-Audio and SACD players are restricted to analog output. The format war between DVD-Audio and SACD has been slow, fairly even, and largely unnoticed by the general public. Initially, players would support either DVD-Audio or SACD, requiring consumers to buy two players to enjoy both formats. Beginning in late 2002, the first "universal" players (progressive scan DVD players that could also play back both DVD-Audio and SACD) began to appear, although these players were expensive and often presented compromises in playback of at least one format. Starting around the end of 2003, the first of a new generation of universal players began to appear, offering better prices and better performance. These players were also some of the first to begin to include some effective bass management for DVD-Audio and SACD's analog outputs. Prior to this, nearly all DVD-A and SACD players lacked any bass management. In response to this omission, Outlaw Audio developed the ICBM-1 multi-channel analog bass manager. For people interested in using both DVD-Audio and SACD but unwilling to buy a universal player, the analog outputs require either two 5.1-channel analog inputs on your receiver (very rare) or some means of switching between them. Early adopters grudgingly took to switching six analog cables from one player to another whenever changing formats. Eventually, some people began using several Radio Shack audio switchboxes to switch between DVD-Audio and SACD players connected to a single 5.1 analog input. Sony produced a multi-channel analog pre-amp called the TA-P9000ES for a time (It was developed to provide multi-channel SACD support on their TA-E9000ES pre/pro), and some hobbyists built their own switchboxes. The TA-P9000ES is no longer in production, but some people still use it as a means of switching between multiple multi-channel analog sources.
HD Discs Blu-ray and HD-DVD
The spring and early summer of 2006 ushered in a new era for the 5" optical video disc: high definition. In April, HD-DVD (which stands for "High Definition DVD" if you hadn't already guessed) arrived with much fanfare, a few players that were somewhat limited by design shortcuts to save cost, and a handful of software titles. In late May or June, the first Blu-Ray discs and players joined HD-DVD on store shelves. Sony's Playstation 3 is slated to arrive in November 2006 and will offer Blu-ray disc playback in a manner very similar to the PS2's DVD support. Both new formats offer true high definition (up to 1080p) video resolution, which is a noticeable step up from DVD's 480 lines of resolution. This greater video resolution is accomplished in both cases by changing from the red laser that CD and DVD use to a blue laser, which allows the data to be stored much more densely. They also offer the same ease of use and audio quality that helped make DVD so popular, and they use the same 5" disc format that CD and DVD users have become accustomed to. This format war is of course reminscent of the VHS/Beta war of the early 1980's. It could also be compared to the much less publicized format war between DVD-Audio and SACD; that war left us with nothing but losers, as SACD limps on and DVD-Audio is largely absorbed by the dubious DualDisc concept. Whether we will see one of these HD formats emerge victorious over the other or both formats coexist in some manner remains to be seen. Blu-ray has the advantage of being supported by seven of the major studios (four of those exclusive to Blu-ray) while HD-DVD has only four (with only one of those exclusive), and the PS3 may grant them a larger user base once it starts shipping in large quantities. The depth of the format library was a deciding factor in the VHS/Beta war, and it looks like Sony remembers that this time, they seem committed to coming out on the winning side of that issue. Whether it is enough to win the war outright remains to be seen, however.
DVD has succeeded so remarkably since its introduction in 1997 for a number of reasons. The improved video quality is noticeable on average TV sets, even if the full benefit is only realized with an EDTV or HDTV display. The improved audio quality is remarkably noticeable by anyone with a home theater sound system, even if that system is little more than a $400 HTiB (Home Theater in a Box). The discs are more compact than VHS tapes, never need to be rewound, and do not suffer from the degradation and wear tape experiences after repeat viewings. The bonus features are often a useful selling point, too, and the pricing structure for DVD has led to many consumers buying movies rather than renting them. HD-DVD and Blu-Ray will face a bit more of a challenge winning over the general consumer. The principal benefit of the two formats over standard DVD is picture quality, but both formats will require an HDTV for that improved picture qualtiy to be experienced. The other features of the two discs will be largely indistinguishable from DVD by most consumers: slightly better audio quality (which I'll touch on below), same optical disc advantages, same sorts of bonus features. The technical differences between the two formats are few: Blu-Ray can store 25GB of data per layer or 50GB on a two-layer disc, HD-DVD can store 15GB of data per layer or 30GB on a two-layer disc, Blu-Ray's standard includes provisions to support two different video compression schemes (Microsoft's VC-1, based on WMV9, and H.246, also called MPEG-4 Part 10) while HD-DVD has locked into H.246 exclusively, and both formats offer the basic read-only format (BD-ROM and HD DVD-ROM) as well as recordable (BD-R and HD DVD-R) and rewriteable (BD-RE and HD DVD-RW) formats with capacities similar to their read-only alter-egos. HD-DVD is more of an evolution of the original DVD format, and as such production costs for discs is lower the same machinery currently used to press DVD's can be retooled relatively easily to produce HD-DVD's. Blu-Ray includes more changes to the underlying disc structure (layers closer to the surface, for example, which allows the data to be packed more tightly and gives Blu-Ray its edge in raw data capacity), which will require entirely new equipment to press the discs and will incur a higher per-disc production cost initially. The key to either format's success will likely lie in the size and quality of the library of titles available, which Blu-ray looks likely to do better in as of late 2006 based on studio support. The only things certain now are that we will be seeing a new format war in the near future, and that it is still far too soon to tell who the winner might be.
I mentioned audio benefits for the two formats, but didn't get into details. Both disc formats will offer three new audio formats: Dolby Digital Plus, DTS-HD, and Dolby TrueHD. DD+ and DTS-HD are basically a logical evolution of the older Dolby Digital and DTS formats offered by DVD. Both provide 7.1 discrete channels (with the capability to support up to 13.1 channels) plus the ability to provide downmixed DD or DTS bitstreams for use with existing receivers and surround processors. Dolby TrueHD can trace its roots primarily back to DVD-Audio and the MLP (Meridian Lossless Packet) lossless compression used there. TrueHD takes MLP and gives it a boost, increasing the bitrate and upgrading to 7.1. All three formats provide the opportunity for improved audio quality over DVD's two formats. As with the arrival of Dolby Digital and DTS back in the 1990's, however, these new formats bring with them a need to support them at the receiver or surround processor as well as at the player. Both formats are turning to digital video as their preferred method of output, meaning that both are going to use HDMI as their primary output. (DVI is pin-compatible with HDMI for video, so DVI displays will work with the new players, but DVI doesn't carry audio.) HDMI is still an evolving platform, unfortunately. HDMI Version 1.1 allows for up to eight channels of PCM audio (or digital bitstreams from DVD-Video and DVD-Audio) and HDMI Version 1.2 adds support for SACD digital bitstreams. Using this delivery system requires the player to decode the original DD+, DTS-HD, or Dolby TrueHD bitstream into PCM before outputting the audio, but that still requires a receiver or processor with support for HDMI and multichannel PCM over HDMI both of which are rare. Players will also have the option of taking those eight PCM channels and decoding them to analog, then using eight analog audio interconnects to deliver the signal to a receiver or processor's multichannel analog input. This multichannel analog input is quite common today (often offering only 5.1 channels, although most newer units allow for 7.1) due to the disappointing format war (or perhaps "format skirmish" since neither side appears to have actually achieved any sort of victory) between DVD-Audio and SACD. A future version of HDMI (HDMI Version 1.3) will probably allow the digital bitstreams to be passed from player to receiver or processor without any processing at the player, much like coaxial and optical digital audio connections behave today for DVD players, but with the ink still drying on the specs for HDMI Version 1.2 it's hard to say when HDMI 1.3 might emerge. My HDMI FAQ contains all the information I've found about HDMI.
So now that you know all about the way DVD and the HD disc formats work, what do you get? A basic DVD player will cost anywhere from $50 to $100; this will get you a progressive scan player with composite and S-video outputs, a component video output, analog stereo audio outputs, and a digital audio output that will pass Dolby Digital and DTS signals. For $200 or so, you can choose from a few players capable of upsampling to HD video resolutions, and if you want to spend more there are players available for well in excess of $1,000. Your player may also offer either DVD-Audio support, SACD support, or both. Any player will support DTS digital output, but don't expect them to have built-in Dolby Digital decoders unless they also include multi-channel support for DVD-Audio (which will generally only appear in players costing $120 or more). These players will also play audio CD's and Video CD's (a video format based on the CD, rarely seen in the US but common in parts of Asia). CD-R and CD-RW discs were once rarely supported, but a recent trend in including MP3 playback support has made CD-R support standard. Most players also support DVD-R (recordable DVD) playback, although support for the other recordable DVD formats (DVD+R, DVD-RW, and DVD-RAM) is less predictable.
What about HD-DVD and Blu-ray? At the moment, that's a tough question to answer: as I write this, none are shipping to the US market. Toshiba's first HD-DVD offerings are less expensive than anything that will be initially available for Blu-ray: $500 to $800. Unfortunately, these players are already known to only offer 5.1 analog audio outputs, Dolby TrueHD support only for stereo output, and video output that is limited to 1080i. The initial wave of Blu-ray players will support 1080p and cost at least $1,000 but we don't know details yet about other features. LG and Samsung have both announced plans to pursue combo players units similar to the "universal" DVD-Audio/SACD players that can play both HD formats but Samsung has not committed to any time table. LG may have something out by the end of 2006 or the beginning of 2007, but there's no word on what the price tag might be.
An important factor in your decision making will be what type of TV you have. If your TV's best input is s-video or less (composite or RF), you will see very little difference between a $70 player from a good brand like Toshiba, Pioneer, or Panasonic and a $1,000 Denon pick up the $70 player and enjoy. If you have an HDTV, however, you can begin to contemplate a few options. HDTV's tha lack a digital video input are probably best off paired with a good progressive scan player. HDTV's with DVI or HDMI inputs can benefit from the upsampling abilities of players like the OPPO Digital for $200, you'd be hard pressed to do better. If your budget can handle more and you also want to enjoy both DVD-Audio and SACD, a player like Denon's DVD-1920 or one of its higher-end siblings could be a good fit. And of course if you have an HDTV and want to try the bleeding edge, either HD-DVD or Blu-ray should give you some amazing picture quality. You may find my DVD Player Chart useful in starting your search; it offers data on a number of current players and I update it once or twice a year. I plan to also assemble an HD Disc Player Chart later this year, once more data is available on the first generation of Blu-ray and HD-DVD players.