THE THX FACTOR by Peter M. Bracke

Certainly, the quest to set consistently workable and comprehensive standards for the production of home theater software and hardware continues unabated within the entertainment industry. Up until the introduction of THX in 1982, there hadn't been any independent, third-party organization to evaluate and apply strict guidelines to the art of motion picture exhibition, nor home consumer products. Unarguably, THX made a significant impact in these areas over the past 15 years, helping to ensure quality presentations in the theater and the home with their Theatrical Alignment, Home Theater and Laserdisc Mastering Certification Programs. Indeed, the moniker THX has become nearly synonymous with the best, and is one of the more instantly-recognizable brand names around.

Though THX has enjoyed a tremendous ride so far, the onslaught of new technology never lies dormant for very long. While not everyone agreed on how soon it would arrive or how profound the impact would be, by the mid-90's, a new technological revolution was clearly on the horizon, and its name was digital. Up until 1996, and the debut of the THX DVD Certification Program, THX's area of expertise had almost solely been in the analog realm. The technological building blocks which celluloid, home theater equipment and the laserdisc and VHS formats rested upon were made up of antiquated components such as magnetic tape heads, sprocket holes, circuits and springs. So despite the improvements THX had helped pioneer in equipment, software and architectural design, the fact remained that such technology was decades old, as was the NTSC television standard on which both the laserdisc and VHS formats were founded.

Digital, Meet NTSC

Certainly, digital technology would not render all of these formats moot overnight, nor would it even aim to replace them. Rather, it would help provide the utmost performance possible from current delivery methods and formats, as well as usher in the arrival of High-Definition Television and digital recording techniques. This issue of "convergence" is perfectly illustrated by the Digital Video Disc format itself, which does not actually alter our current television standard so much as showcase NTSC video to the nth degree of performance. Now, thanks to DVD, for the first time in our own homes (or anywhere, for that matter), consumers could see NTSC video the way most experts and technicians had seen it for years, with quality comparable to that of the original D1 master. Such high performance levels at such low prices would certainly have been unheard of even a couple of years prior.

But, more than just offering higher audio and video quality to the masses, digital technology would redesign the entire process of how content would be created, stored and reproduced. Though on the equipment side digital technology still had to coexist very closely with analog to work, relying on those aforementioned archaic artifacts of wires, springs, analog-to-digital converters and the like, on the software end, it was an entirely different matter. With analog mediums like videotape and laserdisc, production was more a matter of setting your levels, rechecking against your master and then dubbing en masse (though that is a very simplified description). But with digital content and especially DVD, it was now required to author and compress a piece of software, much like a computer game or application. Factor in the added complexity and multitude of interactive options inherent in DVD, like multiple audio and video streaming, variable aspect ratios, and DVD-ROM and DVD-Video convergence capabilities, and the format quickly shattered most of the old paradigms of content creation and duplication.

But it wasn't just the technical side of the equation that was changing. With the rise of DVD, no longer did studios, manufacturers and filmmakers sit back and let a select few independent companies lead the way in terms of licensing, distribution and sales of their products, like they did with the Laserdisc. While format remained, for better or for worse, a niche product, most in the industry sensed that the DVD format offered the sizable opportunity to finally build a true mainstream successor to the venerable VHS format, and of course afford them the opportunity to make tons and tons of money along the way. Indeed, in a matter of just a few short months, scores of industry giants that had previously only taken a token interest in laserdisc and home theater jumped right into DVD with both feet pointing forward.

Leading studios such as New Line, Columbia, Warner and Universal, along with major manufacturers including Sony, Toshiba and Pioneer, took charge of their own product lines and began creating state-of-the-art hardware and software products. Of course, some of these players created the DVD format itself, so it should come as no surprise they would take such an aggressive and early role in the growth of the technology. However, what was new was the fact that unlike the VHS format, which most studios fought kicking and screaming in the early 70's (only to embrace it later as it became apparent that profits would be astronomical), the support for DVD was granted amazingly fast for a new consumer product. Though at the time it seemed like an excruciating wait for DVD enthusiasts anticipating when the latest studio which jump onboard, in reality it was less than two years until all the major studios and hardware manufacturers actively supported the format. By all accounts, DVD succeeded where laserdisc had "failed" with the masses and the industry. It was now big time.

So, were does THX fit into this emerging digital future? Certainly, the THX name carried 15 years of prior experience and esteem, and their plans for DVD were actively anticipated and monitored by consumers, the press and the industry alike. And, of course, Lucasfilm is widely known as a pioneer digital technology, in both the production of motion pictures (most notably with Hollywood's leading special effects house, Industrial Light & Magic) as well as exhibition (with Lucasfilm being the first to project digitally a mainstream commercial release, The Phantom Menace). When THX announced in 1996 that the Laserdisc Mastering Program would soon include the VHS and DVD formats and be renamed The THX Digital Mastering program, the move was not an unexpected one (thought the VHS program was not, however, greeted with the same unanimously positive response by all segments of the industry).

However, as is often the case with pioneers with a considerable history behind them, those who were once students often take notes along the way and soon apply the lessons they learned independently. Thus, many studios, such as the aforementioned New Line and Columbia, began taking their own steps in-house to institute strict quality assurance and standards programs, as well as erecting extensive QC (Quality Control) departments to oversee the final product. With so many studios (who coincidentally were often owned in whole or in part by major consumer electronics manufacturers) no longer looking to third-parties for DVD production, and even usurping some of the methods and practices introduced by THX, would the standard-bearer of the analog age continue to be able to play a significant role in the art of digital software creation and production?

It is worth noting that it was reported by the press that there was allegedly some internal fission occurring within THX at the time of the inclusion of VHS and DVD into the mastering program. Also, there was a measurable displeasure by some home theater consumers (most notably on Internet message boards and forums) about the inclusion of VHS into the program. Though no one would go on record for this story in regards to any internal strife in regards to the inclusion of the VHS format in the mastering program, it hsa been publicly known that there was considerable personnel changeovers aroudn the time, and Tom Holman, who had realized George Lucas' original vision of THX back in the early 80's, would leave the organization completely in 1996. Along with these controversies, further debate ensued afters changes to the THX Home Theater Program were announced. The creation of the THX Ultra and THX Select divisions to their home consumer products cause many enthusiasts and press to accuse THX of attempting to water-down their standards to offer more commercially-viable "higher" and "lower" end products.

With the mandate of the original laserdisc program being to not only provide the highest quality presentation possible but also that which best reproduces the original theatrical presentation, there was even further some dissenting opinion in trade magazines, home theater publications and on web sites regarding the validity of even certifying VHS tape at all, with its limited resolution and other deficiencies of the format versus Laserdisc and DVD. Short of calling it a "backlash," any successful company, especially one as pioneering as THX, is bound to come under criticism. Also, the DVD format is certainly by far the most complicated home video technology yet, and more akin to software than analog technologies like VHS and Laserdisc. And consumer confusion may also have been a factor in the minor debate took place in online message forums in early 1997 that some initial DVD releases bearing the THX logo, such as Warner's early DVD release Twister, were not fully certified by THX. Many questioned the validity of the THX mark so early in the arrival of the format, as the distinction between the mastering of only the transfer versus overseeing the complete DVD authoring and replication processes left some to speculate just what THX was really supervising.

So, with the continued success of THX in the theatrical and home theater markets but yet continuing controversy, we now address these issues and take a more in-depth look at the THX Digital mastering Program today. In researching the following, we were fortunate enough to be able to sit down with THX's Director of DVD Technical Services JC Mitchell, who helped us understand better the technical and quality assurance procedures employed in the THX Digital Mastering Program, as well as Marketing & Sales Representative Charles Busslinger, who shed light on some of the creative and cost factors that effect decision-making on a number of controversial issues. In addition to a brief overview of what differentiates the DVD part of the Digital Mastering Program from Laserdisc and VHS, we'll look at how they face the challenges of such a complex format like DVD, the issues of economics versus faithfulness to the original artistic intent, as well as a look ahead to future developments.

The DVD Certification Process

"(Our) goal in DVD mastering is to preserve the subtle nuances of sound and picture that would bring the home viewing experience as close as possible to the 35mm film experience in a THX certified cinema."

-- Promotional quote from the THX web site

"Our job is to provide the highest quality presentation possible of the best source elements available" THX's JC Mitchell explained, and THX "covers all aspects of the DVD production process from assessing the master through telecine, authoring to replication." Much like they have done with Laserdisc and then VHS, THX offers DVD content suppliers exacting quality control guidelines and specifications to help ensure the best presentation possible, as well as supervising the work from start to finish.

With a strong basis already established with the Laserdisc Mastering Program, much of the procedures and processes employed by the Digital Mastering Program are built upon this previously-established foundation. THX helps the filmmaker choose the best possible film elements, and subsequently supervises the telecine and creation of the masters, including calibration of all equipment used. The patented THX Vertical Interval Test Signal is again embedded as a point of reference in which to track the quality of the image and sound throughout the entire production process against the original master. Concurrent with work on the video portion, THX engineers supervise the Dolby Digital and/or DTS soundtracks to ensure they remain transparent (indistinguishable) from the original master recording, again via the use of their patented test signals. Further, strict inspection of all stages of disc master "stamping" and duplication are assisted, and cross-checking of finished discs over a wide variety of players is employed. (See Part Two for the complete overview of the program,)

However, the complexities inherent in authoring software (and DVD is indeed software) present some new challenges, especially the use of the MPEG-2 compression scheme, as well as the delicate encoding and decoding process. A long period of research and development was conducted prior to the announcement of the Digital Mastering Program, much the same as for Laserdisc. Unlike Laserdisc, however, there is not a conversion from digital to analog anywhere in the chain. Thus, "the encoding and decoding process is extensively supervised and checked, and only THX-approved encoders and equipment can be used." The MPEG-2 scheme employed by DVD uses multiple "passes" to compress redundant information, and therefore fit the large amounts of audio and video data onto a 5" DVD (or multiple discs if required). If you are unfamiliar with the MPEG-2 codec, it looks for information that is repeated over time to reduce into simpler commands. For example, if a single pixel in the same spot were the same color blue for thirty frames of video, those 30 instructions that say "make this pixel blue" could be reduced to a simpler command that says "repeat this pixel 30 times." Though a very simplistic analogy, it hopefully illustrates the cornerstone of MPEG-2, which is its ability to reduce complex commands into simpler ones to increase storage capacity.

THX supervises these multiple encoding "passes" to fine tune the presentation and ensure top quality. With MPEG-2, the first pass is made after deciding on the amount of space allocated on the disc that will be allocated for the video (which is affected by the amount of supplemental amount of material, the soundtracks and type of DVD disc type chosen). Since DVD is a variable bit rate format (i.e., more storage space can be allocated to any part of a program than others), the first "pass" generally encodes the material at a single bit rate over the entire length of the program. Then, compressionists go in and fine tune individual scenes and segments, allocating a higher bit rate for sections that need the boost. Generally, parts with complex action and much movement need more of an allotment, as there is less redundant information in scenes of heavy movement and change from frame to frame. Thus, several "passes" are needed to ensure that artifacts resulting from compression are eliminated, and frame by frame assessements are often made, and the process can take endless days or weeks of work.

Further elaborating on the laserdisc mastering program overview in Part Two, Mr. Mitchell expounded upon the use of the test signals and comparisons to the original master made during the entire process. THX makes three evaluations during the course of the production. First is of the original film source itself to the intial D1 master. The talent is again consulted to make sure all the intial creative decisions (such as color correction, etc.) are maintained from what the original intent for the telecine was. The text signals are compared to ensure there has been no degradation or errors in the conversion. The second check made is perhaps the biggest change between the Laserdisc and DVD mastering programs. Since there is never a conversion to analog made for DVD, there is no D2 master. However, instead, Mr. Mitchell revealed that a "virtual disc" is created (pre-glass master, i.e., the final press master made to physically replicate the discs on the factory line) that contains the fully completed DVD, including full menu navigation, any instructions for Reverse-Spiral-Dual-Layer play, added supplements and all soundtracks and subtitle streams. This "virtual disc" is then again checked against the test signals on both the audio and video portions.

The third, and final, check is made with the completed end product. Again, test signals are compared, as is extensive QC of the disc(s) in a variety of players. Mr. Mitchell added that "player manufacturers are often contacted" about any incompatibility problems, and discs are rejected if there are any defects or glitches in any area of the disc on any player. And as with the laserdisc program, THX supervises and assists in the actual physical duplication and pressing process, as outlined in Part Two.

Another area that is new with DVD is the extensive value-added supplements and interactivity options available to content producers. THX fully advises on most other areas (though not the creative end) of DVD production, including menu navigation, subtitle and language tracks, any streaming or branching features, as well as the use of RSDL (dual-layer). However, as of this writing, THX is not yet overseeing the full certification of DVD-ROM playback in DVD-ROM players. (See the last section of this piece on future plans by THX in this regard).

Content, Creative Decisions and Economics

Just like with Laserdisc, the initial stages of THX's work comes after a content supplier approaches them with a DVD-based project. The first step is assessing the source elements that are available to work with, the budget and and the time frame for completion. Projects can be canceled if the anything in terms of quality, time and/or budget would be detrimental to the finished product. Mr. Mitchell explained that THX sits down with the studio and talent (often the Director and Director Of Photography) to "come to grips with issues such as aspect ratio, formats and any restoration of the original elements" needed or recommended.

However, given the complexity of DVD and the multitude of possibilities it presents, the format presents some unique challenges in the decision-making process on what to leave on or off a disc. THX leaves most of these matters to the content suppliers themselves, making distinctions between what they term creative versus technical decisions. Within THX, whether to mandate options such as the creation of new high-definition masters, anamorphic enhancement, aspect ratio, soundtrack, language and closed captioning options were all issues "that were debated and discussed, and ultimately it was decided that there are certain issues where a hard line in the sand can be drawn, and others where it cannot" Mr. Mitchell stated. Also, other economic concerns by studios are valid reasons to withhold certain format choices, and of course title selection itself is not a part of the THX certification process. "Studios may have their own one-year, two-year or ten-year plans for a title" Mr. Busslinger said, and the studios "have better market awareness and can decide best" what decisions to make in this regard to what format options to release when.

Likewise, though THX does certify High-Definition masters and downconverted anamorphic transfers, these format options are not necessarily required by THX to earn their DVD Certification Program seal of approval. The requirement by THX to only use the "best elements available" is affected by some issues but not others. Complicating factors are what prints and/or film and sound elements can be obtained and how well they have been stored, However, the requirement is not bound by any financial considerations. THX will not turn down a project if a studio or content producer is not willing or unable to come up with funds to improve the quality of the materials or make new masters. However, "there have been some projects that were not undertaken" Mr. Busslinger explained, when the quality of the elements were not acceptable enough to continue.

Sometimes, the issue of artistic intent and the original theatrical presentation can seemingly conflict. The origins of THX were certainly firmly rooted in the theatrical arena, and in accordance to the original intentions laid out in the work of Tomlinson Holman per George Lucas' original vision, as well as via current publicity comments by THX themselves (see the quote that precedes this section), the goal of the Digital Mastering Program was to offer an experience as close to that of the original theatrical presentation as possible. The issue of aspect ratio is certainly a prime example of how replicating the theatrical experience versus a filmmaker's and studio's ain on the home video release can become potentially oppositionall. Mitchell and Busslinger indicated that the goal of THX, however, is always to leave the choice to the studios and filmmakers.

Often a filmmaker will often prefer a full frame version be released instead of the original theatrical widescreen aspect ratio, or times when it will be offered as a coexisting choice to the consumer. A good example are the THX-certified discs of James Cameron's The Abyss, True Lies and Titanic, amongst others, where both P&S and Widescreen versions were certified. Other times, it is a studio decision for marketing and/or economic reasons. As Mr. Mitchell explained "we don't want to dictate or specify an aspect ratio that they (the studio) cannot sell," again pointing to the content producers as being the best able to decide those matters. Likewise, the quality of the source materials are often dependent on budget and availability. The content supplier must asses the market realities and materials at hand, not THX. In essence, with the multitude of aspect ratio and anamorphic options now available, THX functions to offer the best quality presentation within the parameters set by the owners of the material. After source elements are assembled, "recommendations are made by THX to the content producer," in regards to these issues, but ultimately once the project is greenlighted, "we take what we are provided with and make it look and sound the best possible."

The Future

Certainly, many of the decisions made by content suppliers on what to add or not add on a DVD is a factor of not only cost but storage space. Enticingly, THX's Mitchell teased that "we are expecting advancements that will come in the next year or two that will affect today's decisions and open new avenues" for DVD and future advancements. With the imminent arrival (as of this writing) of DVD-18 (double-sided, dual-layer discs), new avenues will indeed open up in terms of the amount of material that can be included on one disc, as well as provide further aspect ratio and viewing options.

Additionally, THX has definite intentions to further the art of DVD-Video and DVD-ROM production by expanding their certification by more thoroughly cover the navigation and interactive elements of DVD. Mr. Mitchell indicated research is currently underway to help content suppliers and manufacturers better utilize the DVD format in terms of increasing ease-of-use in menu navigation and offering more extensive owner setup options in players. For example, options to be addressed include letting the viewer decide whether the menu starts at the beginning of play or at the end, allowing audio tracks to be accessed "on the fly," as well as better player/disc compatibility, to name but a few.

Perhaps the biggest innovation THX is now pioneering is the recent intorduction of their new 6.1 surround sound process, THX EX Surround. Matrixing an additional rear center surround channel into existing Dolby Digital 5.1 sountracks, this added dimension to home theater sound promises to offering filmmakers and artist an expanded canvas upon which to realize their ideas. For more on THX EX Surround, visit our in-depth Spotlight Report.

So, with over 15 years of pioneering work and experience in the art of theatrical and home theater presentation, THX certainly will continue to play a role in the advent of digital technology and the furthering of the DVD format. THX can legitimately claim to having played a key role in the great strides made in analog technology for the consumer market. Given the complex nature of DVD software and the relative infancy of the format, there may be more controversy and divergent opinion (and competition) on what standards should be set, by whom, and how. But in any event, the THX story will continue...

Special thanks to THX, JC Mitchell, Charles Busslinger, Tomlinson Holman, and all the DVD production experts and consultants who offered their time and talents to the writing of this article. For more information, visit the web sites of THX and Dolby Labs.