DVD’s have revolutionized the way we think about television. The digital disc with its remarkably clear picture has shown us that “home theater,” once an exotic concept reserved for the privileged few, can now be embraced by all. For that ultimate movie-watching experience, a new generation of High Definition Televisions (HDTVs), flat panels, plasma screens, and more recently even home projectors can deliver bigger, sharper, brighter, and more enveloping video images than the small, boxy televisions of the past. However, simply buying a larger screen is not enough to truly achieve that movie theater-like ideal. For all of DVD’s advances, it remains a Standard Definition (SD) video format that can use a little help translating to a High Definition (HD) medium. As it turns out, buying your HD display is only the first step in fulfilling your big-screen, home theater dreams .
The Right DVD Player for the Job
Once you’ve found the right HDTV display to center your home theater around, the next step is connecting the right DVD player to it. A common misconception is that DVD is a “plug and play” technology, and that all you need to do is connect any DVD player to the TV by the most convenient video cable and everything will be instantly ready to go. After upgrading to a HD display, home theater fans quickly learn the folly of that mistake. The quality of video on the screen is only as good as the source delivering it, and chances are that the old DVD player you were using with your SD TV will be insufficient for the new display.
In order for an HDTV to show the best possible picture quality, the video signal must be converted to the “native rate” of the display (the primary resolution that the screen supports). This can be performed either within the TV itself, or externally at the video source. How well the conversion from SD to HD is performed by the circuitry in the electronic devices will determine how good the video image looks on screen. Generally, HDTV manufacturers use basic, unsophisticated scaling chips that do an inadequate job of this. In the case of DVD’s, which are still encoded at SD resolution, this is almost always best performed within the DVD player so that the display’s own internal components won’t have to struggle with these steps and can simply present exactly the signal provided to them.
Unfortunately, not all DVD players are created equal. Connecting an average DVD player to a HD display can be a disconcerting experience. Converting the SD DVD signal to a HD resolution may cause a host of video artifacts if not performed properly. These flaws will be especially noticeable on large and high-resolution screens. Quality deinterlacing and scaling are the key components to stable, artifact-free movie watching, and frequently the components built into many DVD players to perform these tasks are not up to the challenge. Low-end DVD players may not even have them at all.
The first criteria to look for in a suitable DVD player for an HDTV display is a direct-digital video connection of either the Digital Video Interface (DVI) or High Definition Media Interface (HDMI) type (the two cable types are compatible; a DVI output on the DVD player may be connected to an HDMI input on the TV via a simple adaptor cable). With this type of connection, the data stays entirely in the digital domain, bypassing the digital-to-analog conversion required with analog output cables such as S-video or Component video. A pure digital video interface avoids the risk of analog signal noise, filtering, or transcoding errors affecting the data. DVI and HDMI deliver exactly the bits encoded on the disc and result in a far more compelling image that is razor sharp and wonderfully vibrant.
The Complexities of Deinterlacing
Since DVD video is stored on disc in a SD interlaced format, in order to view this material on a progressive scan HDTV screen the separate video fields must first be combined into whole frames through a process called deinterlacing. Although the change from interlaced to progressive seems trivial, it greatly enhances the video quality. Lack of interlacing is the primary reason why small text is easily legible on a computer monitor, whereas it has traditionally been difficult to read on a SD TV due to flickering and poor detail.
In order to achieve this result, two interlaced picture fields are merged into a single progressive frame. This may sound simple, but in actuality turns out to be surprisingly difficult to do well. Poor quality deinterlacing will result in soft pictures, “jaggies”, and combing artifacts when interlaced fields are not matched together correctly. Unfortunately, deinterlacing can be easily complicated by the nature of film-based, video-based, or mixed-source content. Good progressive scan DVD players can detect, adapt to, and compensate for the motion in both film and video scenes. For example, the OPPO Digital OPDV971H (www.oppodigital.com) utilizes the renowned “Directional Correlation Deinterlacing”, or DCDi solution by Faroudja, to produce smooth and stable pictures no matter what the content is.
The Benefits of Upconversion
After deinterlacing, the SD DVD video must then be scaled (or “upconverted”) to the higher resolution of the HD display. Scaling involves creating new pixels by selectively copying pieces of the surrounding pixels using various mathematical techniques to interpolate what the video signal would look like at a different resolution. A good upconverting DVD player scales the DVD video using fast processing electronics and intelligent algorithms. It can detect and compensate for motion, scene transitions, foreground and background objects, and noise from video in real time and handle each situation intelligently. The scaled-up video is rich in detail, with little or no visible artifacts introduced by the upconversion process.
There are some upconverting DVD players on the market that cannot do the job well, often because they employ low-quality detail enhancement circuitry to simply enlarge video pixels from the original DVD to fill up the HD screen. Viewers will notice artifacts such as visible pixelation, color shifting, jagged lines, and “ringing” borders introduced by the poor upconversion. These artifacts are often mistaken for digital compression flaws in the DVD itself, when in fact the DVD player and/or display may be causing them. The high-quality upconversion performed by a player such as the above-mentioned OPPO OPDV971H makes certain that what you see on screen accurately represents what is really on the disc.
Once you’ve limited your choice of DVD player to those with direct-digital video connections, sophisticated motion-adaptive deinterlacing for both film and video content, and high-quality intelligent upconversion algorithms, the next step is to look at the feature set and convenience factors that make a specific DVD player the right fit for your needs.
Versatility is the key. Home theater fans require flexibility in the amount and types of content they play. Will the machine play both NTSC and PAL discs with accurate conversion of either video format to the viewer’s display type? Does it offer the stunning sound quality of the high-resolution DVD-Audio format for an audiophile audience? In addition to standard DVD-video, is it compatible with DivX or XviD files with subtitles in multi-formats? Can it support playback of DVD-R, DVD+R, DVD-RW, DVD+RW, CD, VCD, SVCD, HDCD, CD-R, CD+R, CD-DA, Kodak Picture CD, WMA and other audio formats, MPEG1, MPEG2, and JPEG content? Home theater is about more than just DVD. Sometimes the content we desire to watch comes in unusual formats. A quality DVD player must also be a versatile hub ready for all of your multi-media needs.
To further enhance the DVD-viewing experience, select an upconverting DVD player that offers a digital frame buffer to provide an extremely fast layer change transition. Most DVD titles are on dual-layer discs, and a fast layer change helps avoid distractions from unwanted pauses in the middle of a movie.
Another criteria for any home theater connoisseur to have in a DVD player is the ability to upgrade via firmware. As new features are developed for the player, easy-to-install user-upgradeable firmware updates ensure that your DVD player will never be outdated.
As your video display moves into the HD era, don’t leave your DVD collection behind. Even while looking forward to a future with more HD content availability, we must not forget the great wealth of material already available on the DVD format. A DVD collection can represent a sizable investment, both financially and emotionally, in our favorite content. That content deserves to look its very best on any type of screen.
Contributed by: Jason Liao, CTO & VP of Product Development for OPPO Digital Contact information: Telephone: 650-961-1118 or email: firstname.lastname@example.org OPPO Digital, Inc. (www.oppodigital.com), manufactures and markets digital electronics for A/V enthusiasts and video savvy consumers that deliver style, innovation, value, and performance.