Feature Article
Widescreen FULL-Mode Lock: The Full Digital Scaling Solution Part 3
Tapping the Hidden Power of Native Widescreen

As we saw in the previous section, FULL-mode lock is a problem because most consumer DVD players format their output for 4:3 displays instead of 1.78:1, and that the solution is to use a DVD player without this limitation. But where can we find players that correctly format all DVD material, not just 16x9-enhanced, for 1.78 screens? Some high-end set-top DVD players already offer 1.78:1 output for 16x9-enhanced discs. Another player, the mid-range Panasonic RP-91, will reformat 4:3 and non-enhanced letterboxed for widescreen displays. However, the former do not offer scaling, and the latter does not work 100% correctly with "odd" aspect ratios like 1.66:1 (the tops and bottoms of the image are cropped off, something that is especially problematic when the material has subtitles). There are also external "scalers" that will reformat DVD output for 1.78:1, but they are expensive and likely too complex for the average user for the likings of the average user.

One modestly priced solution that is available, though, is the home theater PC or HTPC. HTPCs are PCs, usually Windows-based, that are configured and tuned for audio-visual use. They are capable of a variety of home theater tasks, including DVD playback, scaling, deinterlacing, and decoding HDTV signals; it is the first and second that interest us for the purposes here. Big advances in CPU and multimedia power over the last four years, combined with falling prices, mean that budget machines are now capable of taking over DVD playback away from set-top units, and bringing out the hidden potential locked away in HD-ready displays.

HTPCs excel when used as "scaling" DVD players, capable of reformatting DVD material into native, properly proportioned 1.78:1. There are several ways to implement one of these, but arguably the simplest and most popular is through use of a software DVD player, especially if it is designed for HTPC use (like TheaterTek). By configuring the resolution of the HTPC's video card to an HDTV-derived mode like 856x480 (which we our next example uses for the sake of simplicity), the player's window takes on an aspect ratio of 1.78:1, and henceforth, it is a simple matter for it to format the raw DVD image using the sophisticated scaling implemented in the video hardware. Applying appropriate vertical and horizontal "stretching" (the surplus black bar area is properly cropped off), the image takes on its correct proportions, and is ready for input to the display with no further formatting needed.

Viva Las Vegas appears courtesy of MGM
  Start with raw DVD image of 720x480  
  Start with raw DVD image of 720x480  
  "Stretch" vertically...  
  "Stretch" vertically by 33%...  
  ...and horizontally to fit for a properly proportioned 1.78:1 image  
  ...and horizontally by 19%  

The other type of non-enhanced DVD material requiring formatting is 4:3, and again, it is a relatively simple matter to reshape it for proper proportioning on 1.78:1 displays. If the vertical resolution is 480, though, we have to scale it by "squeezing," which involves throwing away horizontal resolution. A better idea is to set the display resolution higher, at the HD-derived mode of 960x540, in which case the correction is a vertical "stretch" of about 12%.

The Night Stalker appears courtesy of Anchor Bay Entertainment
  Start with raw DVD image of 720x480 (in 960x540 player window)  
  Start with raw DVD image of 720x480 (in 960x540 player window)...  
  ...and "stretch" it by about 12%  
  ...and "stretch" it vertically by about 12%  

In both cases, not only is the image properly formatted to fit the screen without any cropping or resolution loss, by "upscaling" to the higher resolution through scaling in the digital domain (instead of the "dumb" analog stretching employed by most widescreen displays), substantial image quality improvements are realized through finer scan lines and the smoothing of jagged edges (staircasing). All DVDs can benefit from this, especially enhanced ones; reference-quality DVDs like Warner Home Video's Ghost Ship can deliver breathtaking clarity and depth of image, almost bordering on high-definition.


FULL-mode lock is a behavior common to many widescreen displays, especially older designs, where all progressive-scan signals are considered to be 1.78:1, and if anything other, are reformatted to be so. The problem for many widescreen owners is that the progressive-scan output of typical set-top DVD players only works properly with these sets if the DVD software is 16x9-enhanced; non-enhanced letterboxed or 4:3 DVDs will be displayed as distorted, their images stretched out of proportion. This is not due to design flaws or oversights in the displays, but rather to the fact that most DVD players format their output for 4:3 rather than the native 1.78:1 of widescreen displays. By employing a playback solution that formats DVD for 1.78:1 instead of 4:3, such as an HTPC, this is no longer a problem. In addition, if the solution involves upscaling the image in the digital domain, significant improvements in image quality can be realized, especially with reference quality 16x9-enhanced material. Working with native widescreen resolution instead of against it can aid in obtaining maximum performance from these advanced displays, and a tremendous complement to the home theater experience.

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