This article originally appeared in issue #3 of Surround Professional in Februry 1999.

It's been exactly two years since the first DVD-Video hardware and software was made available to consumers in the US. During the first few months after the introduction of DVD, not very many people knew about it and even fewer had the equipment and know-how to create one. The price of purchasing an MPEG-2 encoder, AC-3 compression system, and authoring software was well over $200K and together with all of the other necessary audio and video equipment, computers, hard drives, monitors, and network systems brought the total cost close to $500K. I know because my company, AIX Media Group, was one of those early entrants into the world of DVD-Video.

In April of 1996, we became beta partners for a DVD-Creator system from Sonic Solutions and began to learn the production skills necessary to create a finished DVD-Video master. It took us seven months to produce our first replicated disc (and we beat most of our competitors)! In November of that year during our open house, we played a disc containing the "Tonight, Tonight" music video by the Smashing Pumpkins on a Japanese DVD-Video player. The disc was manufactured in Japan and hand delivered to the studio the day of the party. Unfortunately, after all of the time and expense spent making the disc, flying a person with the DLT to Japan and back with the two discs, the music was out of sync with the video by almost a half a second! Thus we entered the DVD-Video authoring and compression business.

Luckily things are much better in 1999 than they were two years ago, but just exactly how much better is an open question. The price and availability of the software and hardware systems have come down dramatically and there's now a market for the finished product. The public has enthusiastically embraced the DVD-Video format, making it the most successful newly introduced consumer format in history! But the process of creating the various media components, whether it be graphics, audio and/or video, and successfully assembling them into a disc image that conforms to the DVD-Video specification is still a daunting task for even the most experienced production houses. A highly interactive, engaging DVD-Video title is the result of a team of skilled artists, engineers, and designers all working in a carefully coordinated manner. Producing a DVD-Video title is not quite rocket science but it's a lot closer than most people think.

Putting It All Together

It doesn't matter whether you're a major Hollywood Studio or a small independent producer, if you're interested in producing a DVD-Video title there are essentially two different approaches. You can act as your own DVD producer and assemble a team by hiring graphic artists, audio engineers, videographers, translators, voice over talent, editors, special effects houses, authoring and compression experts and testing labs. Or you can off-load the entire job by contracting an experienced DVD production company with all of those capabilities under one roof. The method you choose is determined by your own style, the number of titles you have to produce, the total budget for the projects, and the delivery schedule for finished goods. No matter which method you go with, an experienced team and close communication between all concerned are the most important aspects in the development of a compelling DVD-Video title. After producing over 300 DVD-Video titles for clients such as 20th Century Fox, Morgan Creek Home Video, Warner Bros. Music Group, Capital Records, Sonic Solutions, Motorola, Philips Consumer Products, and Troma Team Video, the most efficient processes become very evident.

In the broadest view, building a DVD-Video title involves creating an interactive plan, designing the menuing graphics, encoding the video and audio and authoring the media components into a completed disc image ready for replication. A more careful investigation of these basic production steps reveals a level of complexity that can confound even experienced developers. Graphic artists used to developing screens for CD-ROM projects are suddenly being asked to understand the production requirements for delivering imagery through an NTSC monitor at 720x480 rather than 640x480 pixels, for example. Developing for DVD-Video can also be difficult for the audio engineers when confronted with choosing between high resolution linear PCM tracks (96 kHz/24 bit stereo) for a music title or 5.1 mixes encoded with Dolby Digital® or DTS®. Even an authoring specialist using the most up to date tools must make creative programming decisions while implementing an interactive design. An end user's experience with a given DVD-Video title can vary greatly depending on the author's knowledge of the DVD format and the design philosophy taken by the interactive designer/publisher. Have you noticed the rather unsettling differences between DVD-Video titles developed by different facilities? Maybe it's time to unify the approach and move the business forward.

Designing For DVD-Video

For graphics professionals looking to create their first set of menus for an interactive DVD-Video title, the tools and techniques are pretty much the same as working on screen graphics for CD-ROM productions.

Designers will use Adobe Photoshop to create the 2D artwork for a menu and then create moving elements with After Affects also from Adobe. However, working with graphics that are eventually going to be displayed on a television monitor requires a starting canvas size of 720 x 480 pixels for static menu screens and 720 x 540 pixels for those intended to include motion elements. And that's only for NTSC standard monitors. Things are different for countries that adhere to the PAL standard. If the product design is specified as a 16:9 formatted screen then the horizontal dimension changes to 960 x 480 (or 540 for motion graphics).

Television monitors have something else to contend with called "underscan" and "overscan". Roughly ten percent of the screen area at the top/bottom and sides can be lost when your artwork is displayed on a TV, not a good thing if you're placing critical elements of your design or navigation buttons in that area. When working in Photoshop, I maintain my "safe" areas by having a grid as the top layer of my design. You can create this grid if you have Adobe After Affects by creating a new composition at your desired screen size (i.e. 720 x 480), turning on the "Action and Title Safe" areas grid and capturing the screen for importation into Photoshop. Remove the opaque black area leaving only the grid lines by using the magic wand tool and you've got a safety grid that can be used for all of your menu design work. By staying within the Title Safe area of your grid even if you're preparing graphics for 16:9 screens, you can effectively produce one master screen graphic for all NTSC formats.

In order to prepare menu screens that have motion and/or composited video elements, the design process includes additional considerations. Instead of working with 720 x 480, the screen should begin with 720 x 540 pixels. After the 2D layered design is complete, a graphics person familiar with Adobe After Affects can create and render a menu full of interesting motion graphics or video. During this final rendering stage the artwork is scaled to 720 x486 (D-1 NTSC resolution) and pixel shape changed from the square type used on computer monitors to the rectangular ones found on television monitors. Check out the recent Leslie Nielsen movie, "Wrongfully Accused", from Morgan Creek to see menus with lots of interesting motion and video transitions.

One final design phase that graphic artists need to supply to the author of a DVD-Video title, is a complete set of "sub-pictures" which exactly match the underlying artwork of a menu screen. These sub-pictures are composed of only four colors: black, red, blue, and white (all 100% color values and therefore heavily aliased!). The author uses the sub-picture overlay to activate up to four other colors (from a flexible palette) that highlight the navigation areas on the final DVD-Video product. It is critical that the sub-picture has exactly the same screen dimensions and placement as the menu screen or the highlight will "jump" when selected instead of residing right on top of the underlying button or text. For still menus, the size of the sub-picture is 720 x 480. For menus that have motion elements, the size changes to 720 x 486 to match the D-1 NTSC rendered video.

There are a few other general things to consider when preparing graphics for television monitors which will insure your screens end up looking like you intend them to look. Design your menus using NTSC colors. There is filter in Photoshop that will convert a standard RGB palette to NTSC safe colors. Avoid using thin horizontal lines or serif fonts smaller than about 24 points. They cause problems on television screens. Finally, remember that your designs are primarily functional and intended to make navigation easy and obvious. A cluttered screen with obscure icons or small text can result in user frustration and product alienation.

Audio for DVD-Video

Audio engineers, artists, music producers, and the record industry have a new creative medium with the DVD format. DVD-Video, together with the eventual introduction of DVD-Audio, can deliver high quality, multi-channel audio with or without video that will fundamentally change the way we create and enjoy music. If you haven't yet experienced stereo music recorded and mixed at high resolution (96 kHz/24 bits) or listened to a well-mixed 5.1 surround music track, you're going to be thoroughly engaged with the possibilities with these new formats. The creative choices afforded musicians and producers will require the engineering community to have new production tools and methodologies in order to realize the true potential of the DVD format. Fortunately, equipment manufacturers have begun to respond with high-resolution digital converters and digital consoles equipped with 5.1 surround capabilities. For consumers, its going to mean a completely new audio experience using home entertainment systems upgraded to handle the increased bandwidth.

The DVD-Video specification accommodates a wide variety of digital audio formats and quality levels. Depending on the design of a proposed DVD-Video title and the space availability on the planned disc, audio can be prepared accordingly. Because it is possible to switch between up to eight simultaneous audio tracks in the DVD-Video format, producers can provide consumers with a choice in their selection of audio formats depending on their particular hardware setup or personal preference. DVD-Video producers can place stereo PCM (48 kHz), 5.1 surround in Dolby Digital or DTS, or even SDDS on several of the tracks allowing users to select between them using the AUDIO button on their DVD-Video remote controllers. Most new DVD-Video players provide DACs capable of playing high resolution stereo audio at 96 kHz/24 bits (we'll leave open the question of the actual playback quality!) which could be included on a disc under a separate menu item. Due to the bandwidth required for 96 kHz 24 Bit audio, simultaneous video playback is usually avoided.

Audio engineers should make every effort to capture their mixes, whether stereo or 5.1 surround, at the highest sample rate and longest word size possible. As recording and mastering studios acquire the new machinery required to work in these high resolution formats, the possibility for delivering and archiving 96 kHz/24 bit audio will become commonplace. For now, the choices are limited. Most audio for DVD-Video titles is delivered at 48 kHz 16 bit on one of the 8mm 8-track digital formats such as DA-88 or PCM-800. Some of the newer multi-track digital machines are starting to include 20 and 24 bits but few have embraced higher sample rates. One notable exception is the new Genex 8500 MO recorder/reproducer from HHB, a machine capable of high-resolution recording and playback using internal or external converters. The deck can also be outfitted with DSD for those favoring the new SONY/Philips digital format.

One of the most over-looked production steps associated with audio intended for DVD-Video delivery is the crucial and final mastering stage. Because most DVD-Video titles were originally Hollywood features, they are generally converted into the Dolby Digital format (either 2.0 or 5.1) without any additional dynamic processing by the authoring and compression facility. If, as is now quite common, the DVD-Video producers have included lots of additional materials such as interviews, trivia questions, previews or special features, the non-linear capabilities of the DVD-Video format require the audio to be consistent in level and harmonic content. The situation is even more critical for music-centric products. What might be a simple conversion of a series of music videos or a live concert video when interspersed with interviews or behind-the-scenes footage demands a mastering session. Mastering engineers must deal with audio in a variety of formats, from stereo to full 5.1 mixes and with sample rates from 48 to 96 kHz.

Only after carefully preparing all of the audio in linear PCM format should the encoding step be taken. Most DVD-Video movies have audio that is "perceptually encoded" in Dolby Digital format in 2.0 stereo or full 5.1 surround. Most of the music DVD-Video titles that we have prepared for Capitol Records, Warner Music Group, or Image Entertainment have, in addition to the Dolby Digital tracks, PCM audio versions at 48 kHz 16 bits. Producers also have the choice of encoding their audio in stereo or 5.1 surround using a method developed by DTS (Digital Theater Systems) that substantially increases the audio fidelity, but requires the use of a DTS decoder. Producers developing DVD-Video music titles should definitely check out tracks encoded using DTS.

Video: MPEG-2 Compression

The video quality of the DVD-Video format is what has prompted many reviewers and industry observers to laud the format. And they're right with a comment. The quality of any MPEG-2 video stream is critically dependent on three things: the quality of the source material, the visual content of the program, and the bandwidth allocated to the video based on available disc space and program length. Of the two types of MPEG-2 video encoding methods being used in the preparation of DVD-Video titles, VBR (variable bit rate) and CBR (constant bit rate), the former is the most common.

As previously stated, Hollywood movies make up the vast majority of DVD-Video titles and are generally about two hours long. In order to accommodate the entire movie, the menus, the various language tracks, and special features, the actual video content needs to be compressed within the smallest space possible without sacrificing quality. Using the VBR method of encoding, the bandwidth allocated to any given scene in the film is dependent on the complexity of the material present on the screen. If the section is fairly static then the bit rate can be lower, and conversely, if there is lots of action on the screen then the compressist needs to increase the bit rate. CBR, on the other hand, maintains the same bit rate throughout the film. For shorter features or music video projects, CBR can offer higher quality and less production time (and therefore less expense).

Authoring a DVD-Video

The DVD-Video specification is a very complex document describing all aspects, both physically and digitally, of a properly formatted disc. The process of assembling the graphics, audio and video into a finished product is known as authoring. The process involves the importation of all media elements over a high-speed network to the local machine, building the navigation and highlighting using the menu graphics and sub-pictures, and simulating the user experience prior to multiplexing the final disc image. Authoring specialists must be intimately familiar with the capabilities of the DVD-Video specification, the software system they're using to build the title, and the computer operating system and hardware platform.

From a predetermined interactive map, the author assembles the component media parts into the TITLE MANAGER section of the disc and within VIDEO TITLE SETS (VTS) using PROGRAM CHAINS of video and audio. A comprehensive explanation of the inner workings of the authoring process is beyond the scope of the present article, but it is important to realize that the format is fundamentally a random access, high quality video and audio delivery platform playable in your home entertainment system. And the biggest benefit for producers of DVD-Video titles is the lack of technical support required after the sale (contrast that with CD-ROMs)!

There is great flexibility in the manner in which an individual author assembles a DVD-Video title, a situation that unless clarified could slow the growth of the format. For example, some authoring and compression facilities have opted to ignore the TITLE function and others restrict themselves to a single VTS rather than exploiting the full range of DVD-Video's navigational possibilities. DVD-Video can be a highly interactive format complete with conditional branching and limited score keeping. One of the most robust uses of the format can be seen in the re-release by Digital Leisure of Dragon's Lair, the 1980's arcade game, in the DVD-Video format.

DVD: It's Here Now

DVD-Video is already transforming the home video industry. For the record industry, the implications of the DVD-Video and DVD-Audio formats are even more promising and profound. This new format is a true convergence medium accessible to every consumer, not just those comfortable in front of a multimedia computer system.

Imagine a single disc containing a complete album experience in 5.1 surround or high-resolution stereo, complete with a series of music videos or a live concert shot in multi-camera angles. The same disc could contain printable sheet music unlockable through a web connection, direct access to the band's or label's Internet sites, interviews, lyrics, games, posters, and anything that can be digitized and pressed into the surface of an optical disc. The format can to do all of these things. It's limited only by our imaginations.

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Mark Waldrep, Ph.D. is the Founder, CEO, and Chairman of AIX Media Group, a company specializing in the innovative use of emerging technologies such as DVD and the Internet. He is also an associate professor in the Division of Performing and Media Arts at the California State University at Dominquez Hills.