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HD-DVD Should Be All That It Can Be: 1080 Progressive
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There's a lot of talk about High Definition DVD going around. Joe Kane has been singing the virtues of a 720 progressive DVD format for the next-generation of HD-DVD. Others have talked about going with a 1080I version of HD-DVD to compliment the many 1080I displays that are becoming available. But both of these positions are shortsighted; 1080 progressive should be the minimum resolution accepted for any new HD-DVD format.
The short version of this story is that 1.) we already have 1080P source material, 2.) 1080P DVD players could easily downconvert to any other display resolution such as 720P or 1080I, and 3.) it won't be long before 1080-Progressive video displays not only become the norm, but become affordable. Want the details? Read on... VIDEO RESOLUTION
First, when we introduce a new DVD format for High Definition video signals, we shouldn't limit it; it should be all that it can be. Who wants to reintroduce a new format that requires new video players every year or so to follow the trends of technological evolution? Let's just do it right the first time, shall we? Any HD-DVD format based on 720P or 1080I encoding would become obsolete before it reached any significant consumer base. Studios are already mastering film in a 1080-line Hi Definition resolution that is perfectly suitable as source material for a 1080P DVD format. Why take a step backward right from the start?
Second, now that we're talking about digital signals, it makes the most sense to record the medium with the highest resolution possible and then rely on the playback hardware to downconvert that signal for less-than-optimal displays. Right now we have 16:9 DVDs which are downconverted to 4:3 letterbox for non-16:9 compatible displays (variations in the quality of conversion software exist, but the software is improving and will continue to improve) so the DVDs you buy can be recorded with maximum resolution regardless of what aspect ratio of television you have. Likewise we have HD-DTV tuners that take 1080I and 720P signals and (down) convert them to whatever resolution/scanning rate matches with your particular display.
In the same way, 1080P DVD signals could be easily downconverted to 1080I, 720P, 480P, and 480I (both 16:9 and 4:3 aspect ratios).
Even if HD-DVDs were encoded as "1080I Format" we could still generate 1080P output from tomorrow's HD-DVD players the same way we output 480P from today's DVD players. However, without a true "1080P" designation our software might still be limited in some respects. The difference between a progressive encoded signal and its interlaced counterpart (just talking about film for the moment) is not just the scanning rate. Before a progressive-scan signal can be interlaced it is first filtered for much of its vertical detail to reduce shimmering and aliasing in the final interlaced image. It's important that the future HD-DVD system be established with a vertical resolution of 1080 progressive because you don't want the studio applying the vertical-filtering to the signal for you, thereby compromising the signal on your disc. With a true 1080P DVD source, the DVD player would provide the necessary vertical filtering if and only if the image was to be downconverted for an interlaced display, thereby allowing maximum vertical resolution for those who are progressive-scan-capable.
It should be pointed out that when film is the source, it doesn't require any more bits to store 24 frames of progressive-scan video vs. splitting those frames into 48 fields and storing it as interlaced. This is a concept that many industry "experts" and studio execs have a hard time grasping, as their thinking can often be locked into the analog world from our shadows and all it's real-time bandwidth limitations.
BUT WILL 1080P EVERY BECOME AFFORDABLE FOR THE MAINSTREAM?
YES, and probably within just a couple of years. Currently, only very costly and high-precision CRT projectors are capable of delivering 1080P without overlapping scanlines which is why many are quick to dismiss 1080P as ever becoming a market reality. But this is going to change.
Firstly, we're currently looking at a price-structure for high-end projection products that are not influenced by mass production. Heck, a radio once cost the average man's yearly salary! Secondly, who says that CRT is the only way? The future is DLP, LCD and other chip-based digital projection technologies. Hey, if you've got a chip with 1080 vertical pixels of resolution...you've got 1080P! The performance of such digital display systems will only get better and their price will drop dramatically over the next few years. Just watch and wait.
DON'T PLACE LIMITS!!!
It's important not to arbitrarily limit the quality or features of HD-DVD to only what is a commercial reality upon its inception. Joe Kane may like 720P because it's easy to build CRT projectors that can do it, but anyone who doesn't have their head in the sand can see that CRT technology is stepping aside for digital projection technology as it slowly, but surely, evolves. Joel Silver from the Imaging Science Foundation supports this perspective when he says:
"We must not limit ourselves to short term CRT based thinking when planning a system for the future. Even though 720p is certainly CRT friendly, solid state systems such as Texas Instruments DLP, JVC DILA, Sony GLV, LCD and plasma devices will certainly be able to take advantage of 1080p. Any serious discussion regarding HDTV must take into account the natural progression towards solid state devices from our vacuum tube based roots."
Thanks for agreeing with me Joel! Anybody interested in a more technical discussion expressing how the ISF and other industry HDTV gurus feel, please click here for an excellent paper written by Dr. William Glenn.
1080P AND BEYOND...
HD-DVD should be forward-thinking and include in the HD-DVD specifications yet-unutilized features of the MPEG2 spec like 20:9 encoding. This is useful for 2.35:1 movies that still get letterboxed in a 16:9 frame, thereby sacrificing vertical resolution. In a 20:9 frame, 2.35:1 films fit with only a handful of scan-lines/vertical pixels above and below offering a significant increase in vertical resolution over normal 16:9 encoding. If you thought that 16:9 encoding of DVD increased resolution for widescreen films as compared to 4:3 letterboxing, 20:9 encoding offers the same advantage for 2.35:1 films over 16:9 letterboxing that 16:9 offers with 1.85:1 films over 4:3 letterboxing.
An example of how this is important: The digital projections of the 2.35:1 Star Wars: Episode One used a 1080-line Hi Definition signal, but "anamorphically" encoded the film to use all 1080 lines rather than "letterboxing" the 2.35:1 aspect ratio image in the 16:9 frame (the digital projector used an anamorphic lens to unsqueeze the image). In other words, digital projection in theaters will be making the most of all 1080 vertical pixels for maximum resolution, and since 20:9 encoding is already a part of the MPEG2 specification, it easily could be offered as an option for those studios seeking to provide HD-DVDs (of 2.22:1 films or wider) with the highest native resolution. Do you want the public theater to get more resolution than your home theater?
It's also important to leave plenty of room for future technologies like greater than 1080P resolution and 3-D video. As stunning as our current HD-system may be, it's clearly got some room for improvement after stepping out of a 3-D IMAX presentation. Let's not pretend our 1080 lines have really given us that long hoped-for "window" to look through just yet.
Talk to many DVD collectors who also collected laserdisc and they're likely to tell you that while DVD offers a better picture than that of laserdisc (dramatically so, if you're taking advantage of DVD's 16:9 and component-480P potential), the Dolby Digital compressed sound just doesn't quite deliver the visceral realism of the old-fashioned 16/44.1 PCM on laserdisc when comparing channel-for-channel fidelity (which is scary when you think that audiophiles even criticize 16/44.1!!!). Higher bitrates for DD as well as the provision for DTS can do wonders for audio, and many hold the opinion that DTS, providing 20-24-bit resolution, despite lossy compression, can sound superior to 16/44.1 linear PCM.
But why stop there? Our HD-DVD should deliver the highest quality image and sound. Therefore, Merdian's Lossless Packing (MLP) should be part of the standard (handling resolutions of up to at least 24/196) as well as Sony's Direct Stream Digital (DSD) audio. More than six channels should also be permitted. Why matrix a center rear-channel for Dolby Digital EX when you could record it discretely? The future may prove to have more bandwidth and bit storage than we need. Why not allow for audio that is virtually transparent to the source?
IF HIGH-QUALITY VIDEO AND MULTICHANNEL AUDIO ARE PART OF HD-DVD, THEN WE DON'T NEED ANOTHER FORMAT FOR AUDIO
In this way the same HD-DVD platform could provide both video and high quality audio even for audio-only applications. Why create two separate disc incarnations deemed "video" and "audio?" Why not have one simple disc platform that plays in all players and does everything?
THE FUTURE HAS PLENTY OF BIT SPACE
New developments like C3D's (http://www.c-3d.net) Fluorescent Multi-layer Disc with the promise to hold 140GB on a DVD-sized disc will negate the issues that have limited our audio and video quality in the past. Only political ownership and copyright issues will stand in the way (not to underestimate their significance) of quality. The profound increase in storage capacity along with data bandwidth of such technologies makes all of our videophile/audiophile dreams possible.
Why try to close the lid now with 1080I or 720P? If Joe Kane wants he can watch his HD-DVD movies downconverted to 720P for his CRT display while I watch my them in full-1080P resolution on my digital projector. Whose guest would you rather be when HD-DVD starts spinning?