Philip De Lancie

With the market for DVD still so new–and fraught with potential pitfalls–multimedia developers and publishers may initially find the idea of “reissuing” existing CD-ROM titles on DVD to be a safer bet than developing new DVD content from the ground up. In a previous article (December’s “Mining the CD-ROM Vaults”), we looked at how two successful multi-disc CD-ROMs, Riven and The Journeyman Project 3: Legacy of Time (both from Red Orb Entertainment, a division of Broderbund Software in Novato, California), were prepared for re-release on DVD-ROM with the help of DVD developer DVant Digital (also from Novato). This time, we’ll examine–once again through DVant’s eyes–the tougher job of converting a CD-ROM title to play back on DVD-Video players. The title in this case is a two-CD set called Shadoan from Digital Versatile Disc, Inc. in Van Nuys, California.

According to Lee Kasper, CEO of Digital Versatile Disc, the CD-ROM version of Shadoan was awarded “Best of Show” at MacWorld 1998, and received the “Parent’s Choice Approval Award” for excellence in children’s entertainment in 1997. “Shadoan is an interactive children’s title,” Kasper says, “which follows the heroics of its central character Lathan Kandor, who must reassemble the missing parts of a magic amulet and return them to the beautiful Princess Grace Delight in order to defeat the evil wizard Torloc. It has a unique Parental Guidance Mode which enables parents to adjust the level of cartoonish fighting scenes to what they consider appropriate for their children.”

Kasper says Shadoan features “more than 70,000 hand-painted cells or animation, and took over nine months to complete using over 300 animators working around the clock. The soundtrack contains 30 original musical scores which were created by composers known for their arrangements for Pocahontas and Beauty and the Beast. Julie Eisenhower’s CD of the soundtrack is on the music charts.”

The DVD version of Shadoan is scheduled for worldwide release in November at a list price of $49.95 for a product that includes both DVD-ROM and DVD-Video versions of the game. “They will both be on one DVD-9,” Kasper says. “One layer will be DVD and the second layer will be DVD-ROM, all packaged in the same box.” The title will feature DTS 5.1 channel sound, six languages, and IBM speech recognition technology for voice input. “The DVD format needs something great in this genre,” Kasper says. “We feel that Shadoan will be the most interactive product out on DVD for a long time.”

While Kasper is evidently excited about Shadoan’s place on the front lines of DVD gaming, converting the title to DVD has apparently proven more of a challenge than originally anticipated. “We did not expect this project to be 20 weeks or longer when we first decided to put it out on DVD,” he says. “We are on schedule, but we did not realize the extent of the project.”

For the DVD-Video portion of the title, DVant is handling the authoring, but not the audio and video encoding. DVant’s “project lead” for Shadoan has been Jesse Hiller. “I wrote the project outline and did all of the testing and development,” Hiller says, “and will handle the bulk of project development through completion. Mark Johnson, our CTO, has helped me uncover many of the solutions to the technical challenges.”

What makes Shadoan a good candidate for conversion to DVD, Hiller says, is that “Shadoan is basically 350 video clips strung together with navigational menus and commands. This makes it ideal for the DVD-Video format, which works by linking video clips together in the same way.” Hiller points out that the DVD-Video portion will be playable from a PC DVD-ROM drive as well. “The reason we at DVant Digital focus on the DVD-Video format is that it is an open platform, which means that you can play a DVD-Video title on your set-top box and also on your Mac or PC with a DVD-ROM drive. This way you can reach more people with the same product and have it work the same on all platforms.

As far as taking advantage of the capabilities offered by the DVD-Video specification, Hiller says Shadoan was done with “Disney-style animation and award-winning audio, so that is a natural for DVD-Video’s MPEG-2 video format and hi-fidelity audio formats. And DVD-Video really lends itself to this type of interactivity.” Delivering CD-ROM-style interactivity under the DVD-Video specification is no mean feat, however, because set-top players have nowhere near the processing power or memory capacity of multimedia computers, and the navigational possibilities are tightly defined by the commands available within the DVD-Video specification.


Because CD-ROM and DVD-Video are fundamentally different beasts, the process of recreating the functionality of a CD-ROM within the structure of the DVD-Video specification is not a matter of a simple port or language translation. “This is essentially starting from scratch,” Hiller says. “We take the project specs for the CD-ROM and map it into the DVD-Video spec. The game script is directly portable, but there are aspects of game play that require special handling. It is essentially a process of translating a movie script into machine code.”

“The first thing we did for Shadoan was to write a project specifications paper. To do this, we tested the feasibility of the project,” Hiller recalls. “There are some fairly non-trivial authoring obstacles that had to be thought out and tested thoroughly. After finding the solution to each authoring obstruction, we developed a production schedule, laying out the stages in which tasks must be accomplished, what assets will be required for each stage, and approximately how long each stage will take. The difficulty at this stage lies in the amount of testing done. A poorly tested layout will blow your schedule and that is what clients need to know–how long will this take?”

Hiller continues, “The next step is to begin work on the project layout. That entails organizing all of the assets into logical groupings, according to game play. There are portions of the game that need to reside physically next to each other on the disc in order to work. An intimate knowledge of the game is paramount to the developer at this stage. I can’t tell you how many times I’ve played Shadoan,” admits Hiller, “but I can’t imagine authoring it without experiencing the game first hand.”

The final stages of the development cycle center on testing. “As there is nothing like this out on DVD-Video yet,” Hiller says, “it will be a great opportunity for testing players. All of the authoring is being done in Daikin’s Scenarist II DVD on an SCI O2,” Hiller adds. “We also have an NT emulator with a Cinemaster II board in it. We have all of these systems networked via 100BaseT Ethernet, so we can zip things around fairly quickly; a project like Shadoan has hundreds of assets and all have to be processed at some level. For testing and development, all of the graphics are being pulled off of the original CD-ROM and manipulated on either a Mac or PC. On the CD, all of the graphics are in Targa [.TGA] format and animations are movie files [.MOV] with some Targa file overlays. These files have to be re-formatted to TIFF (.tif) files and resized for playback on NTSC monitors. So even for testing, there is a considerable amount of prep work done.”


The primary challenges identified by DVant in the initial feasibility evaluation centered on processing power, memory limitations, and navigational flexibility. “Since a DVD-Video player has limited processing power in comparison to an average desktop or laptop computer and DVD-Video has a very limited amount of memory,” Hiller says, “all of the processing that those computers would do while playing a CD-ROM must be done before it hits the player.

“In Shadoan, for example, there are timed segments that display sands slipping through an hourglass while a clock is ticking. On the CD-ROM version, this is done by displaying a slideshow of the hourglass over the current frame of video, creating a composited effect. To do this in DVD-Video, you have to actually create a video clip of the scene with the hourglass running and the clock ticking. I refer to this as `hard-coding’ the video because you are physically compositing the video clip of the hourglass and the frame of video together. Thus, instead of displaying three separate streams of information to the screen for varying amounts of time, you are sending one stream of information with all of the `overlaid’ streams embedded into it.”

DVD-Video’s memory constraints, meanwhile, pose enormous problems when attempting to emulate the game play of a CD-ROM. “There just isn’t any memory,” Hiller says, “and with Shadoan, memory is needed at every step of the game. The game is split up into finite points on a map. At every location on that map, alternate takes are shown to the player according to the game-state: the player’s health, objects the player has picked up, objects the player has used at that location, and the like. There is also the matter of storing what types of objects the player has acquired during the game, whether the player has overcome certain obstacles, what stage of the game the player is at, and a number of other various parameters.” To handle all these variables, Hiller says, “there are only 256 register bits available for temporary storage. This storage comes in the form of 16 General Parameters (GPRMs), which are 16-bit storage units.”

These limitations forced DVant to rethink the way memory was used, with efficiency as the number one criteria. “The first storage issue we faced was how to keep track of the inventory objects,” Hiller explains. “In Shadoan, there are 20 items that you can take with you in a magical backpack. This problem was solved by assigning a bit to each inventory object. This way you just flip the bit when you acquire an item, and flip it again when you use it or lose it, so the entire inventory can be handled with just two GPRMs. In general, that is the approach we took with the rest of the game. Each decision that made an impact on the game is stored in memory as one or more bits. When decisions are made that refer to the original decision, those bits are called up from memory and used to direct the player to the appropriate response.”

As for emulating the CD-ROM’s conditionality and navigational flexibility, DVant’s options were basically limited to the pre- and post-commands associated with DVD-Video’s “program chains” (PGCs). One hundred-twenty-eight such commands–broken into categories such as “Jump and Link,” “Calculation,” “Comparison,” “Parameter Setting” and “Program Flow”–are defined in the

specification’s DVD command set. “Shadoan is a scene-based progression of events,” Hiller explains. “At every scene, there are a number of different choices available for selection by the player, and these options may change as the game progresses. So the scene-mapping for an early stage in the game is different from a later stage. Thus, we are programming dynamism into the static DVD-Video structure.”

As an example of how this works in practice, Hiller says that “in many cases, for a given location on Shadoan’s main map, there are three alternate scenes available. The first time the player gets there, the encounter scene is viewed, the second time, a second scene is viewed, and for the rest of the game, a third and final scene is viewed. The bulk of this decision-making is done in the pre-command area of the PGCs. Each time the player comes to this location, he is actually sent to the first scene (PGC 1). If he has already been there, then he is sent to the next scene (PGC 2), and if he has already viewed that scene, he is sent to the last scene (PGC 3). So, at each scene, a decision is made based on whether the player has already viewed that scene, all handled in the pre-command. It really makes decision-making much easier.”

All in all, then, DVant’s experience with Shadoan shows that a DVD-Video title adapted from a CD-ROM is more like a twin than a done: the appearance of the two may be essentially similar, but many details and internal workings are actually quite individual. Translating one to the other can be a formidable chore, but for titles that rely more on rich atmosphere than instantaneous “twitch” response, DVD-Video potentially delivers an enhanced experience despite its limitations, capturing the essence of the CD-ROM, while imbuing it with the delights of premium quality visuals and sound.

companies mentioned in this article

Digital Versatile Disc, Inc. 15210 Keswick Street, Van Nuys, CA 91405; 818/994-2980; Fax 818/994-1575;; INFOLINK #403

DVant, Inc. 1850 Ignacio Boulevard, Suite 212, Novato, CA 94949; 415/9068; Fax 415/883-9563;; INFOLINK #405

Philip De Lancie ( is a freelance writer covering media production and distribution technology based in Berkeley, California.

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