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MillimeterDefensive DVD Authoring
Mar 8, 2006 12:44 PM
Barry Braverman
You know what I'm talking about. Your check disc comes back from the replicator and there are problems. Maybe one or two menu buttons mysteriously don't work or the disc plays back in fits and stumbles. Perhaps the navigation is exhibiting erratic tendencies, illogically executing post-commands or end jumps. Of course the replicator blames YOU and insists that you (or your client) pay for a new glass master to the tune of $1000-$2000.
But wait a second. You proofed this project a half-dozen times and verified it in the authoring software's simulator. You even burned an image from the authoring software to a recordable DVD-R (or +R) and all seemed well. So why does the replicator, or worse your client, automatically blame you?
Two reasons: 1) because scapegoating is a universal human attribute, and 2) because you the DVD author oversees enormous complexity (whether aware of it or not) and therefore have ample opportunity to screw things up. So when things do go wrong, as they are apt to in some way on almost every project, guess who takes the heat. It's not the replicator's blurry-eyed QC tech on the graveyard shift or the heavily abstracted DVD authoring software that's easy to use but produces a nasty and convoluted mess of a file structure. Clients and replicators will readily blame the author for every playback anomaly, which only underscores the need to protect your reputation and career by authoring defensively.
STUPID DVD PLAYER
I emphasize this unfortunate fact in my studio-level DVD authoring classes in Hollywood. Stupid players prone to doing stupid things are the scourge of the industry and mankind, and if allowed to control events, will quickly torpedo the work of even the most vigilant authors.
Remember DVD players are NOT computers. They have no reasoning power beyond the ability to apply basic logic mostly in the form of if, then commands and generally in the context of a single variable(1). DVD players without direction or a firm instruction can be highly unpredictable; indeed, you never know what the player might do. In a common failure scenario, a LINK/Next command initiated by the viewer might not have a legal destination such as a Part of Title or chapter marker specified by the author. The player may simply do nothing in response to the viewer's request, display the next asset physically configured on the disc, or venture somewhere else, say, to an unauthorized Easter egg.
I had one student working in a DVD facility in Hollywood who would surreptitiously insert his business card into every project he authored. Of course he walled off the navigation he thought to the concealed TIFF in order to prevent access except by a secret series of keystrokes. Of course some stupid player somewhere stumbled onto the author's Easter egg quite by accident, and the rest is history: that author is in another line of work right now.
One implication of stupid DVD players is the shifting of complexity from the display environment as in computer games, to the authoring realm where elementary streams of audio, video and subpictures(2) are precisely merged (multiplexed) to form a single stream that can be imaged to disc, DLT, glass master or stamper.
AUTHORING SOFTWARE
Your authoring software is responsible for managing this complexity. And while these programs must all arrive at the same multiplexed VIDEO_TS folder, the efficiency with which this process is performed is often less than ideal in heavily abstracted authoring programs that rely on idiot-proof interfaces. These programs among the most popular on the market offer the apparent benefit of ease-of-use, but often at the price of a sprawling file structure that can give some DVD players conniptions.
SIMULATION VS. EMULATION
The most popular authoring programs today provide proofing in simulation. This approach facilitates the construction of menus, for example, inside the authoring environment and obviates the need for a potentially more reliable and substantial hardware solution. In simulation the elementary media streams are proofed in rough synchronization; audio and subpictures/subtitles are not locked to picture and are allowed to drift to ensure smooth playback on the computer desktop. Proofing in simulation does not reflect the eventual performance in a DVD player, however, as players can only reproduce projects from the multiplexed volume that has been imaged to disc.
DVD players decode the audio, video and subpictures from a single multiplexed stream called a VOB (Video Object). The proofing of VOBs in the authoring software will yield a far more accurate picture of how a project will actually perform when imaged to disc. Proofing in emulation as this process is called was actually much more common several years ago in early versions of Apple DVD Studio Pro, for example, in versions 1.0 - 1.5. Proofing the multiplexed VIDEO_TS volume and VOBs in a software player like the Apple DVD Player should be a regular part of your proofing ritual.
Keep in mind that outputting DVD-R, +R, or DL media is the only reliable way to truly proof your work and gain necessary piece of mind. Recordable DVD media is quite different, however, from a true DVD-Video disc, the former containing microscopic droplets of dye that change color when "burned" to simulate the physical pits in a replicated "pressed" true DVD-Video disc. Since the recordable disc is only a facsimile of a DVD, many players scoff at the apparent ruse and erratically play back the home-brewed DVD variety. Of course during proofing, the competent author must distinguish between anomalies in playback due to recordable media snafus and potential authoring errors that will ultimately appear in the replicated title.
SUBMISSION VIA DVD-R (OR +R)
Submission of the DVD image for replication is still best achieved via DLT (Digital Linear Tape). Yes, these vintage machines are notoriously ornery, and they require an oh-so-retro SCSI card for your Mac or PC. The drives are also quite slow and the tape cartridges themselves rather expensive. But as the industry's last read-after-write format, DLT uniquely provides a perfect bit-for-bit clone of the muxed volume output by your authoring script.
The use of Firewire drives and DVD recordable media for plant submissions do not offer anywhere near the necessary assurance that all is well in DVD-Land. Submitting DVD-R General Media discs for replication can be particularly risky as abundant errors burned into the disc's substrate are ultimately transferred to the glass master or stamper, where additional errors introduced there may compound the problem. The accumulation of errors atop of errors can well lead to playback anomalies in the replicator's check disc.
DEFENSIVE MANEUVERS
You can protect yourself against an unforeseen calamity by following a few key defensive authoring techniques:
- Proof DVD-R and DL discs on multiple players. Actual authoring errors will be apparent and consistent across several playback environments.
- Recruit a fresh set of eyes for proofing chores. After umpteen hundred viewings, the omniscient DVD author can become oblivious to the most obvious defects. Pay particular attention to such matters as misspellings in menus and background composites. You might not think so, but as an author such content defects are as much a part of your business as an incorrect programming command.
- Verify in particular that the MENU, TITLE, NEXT and PREVIOUS buttons on the player remote work and navigate properly. Inoperable buttons or buttons that go nowhere are invariably construed as serious defects by the client, and will often lead to a client's rejection of the check disc.
- Output directly from the authoring script to DLT. Then check the DLT image by burning it to disc. If you can produce a working DVD, your replicator should be able to do the same. In DVD Studio Pro 4, the READ DLT option now allows easy retrieval of the submitted image for verification. PC users can opt for the indispensable GEAR Pro suite of utilities to accomplish the same goal. [www.gearsoftware.com]
Having a fully functional DVD on the shelf is the single best thing you can do to protect yourself against the Blame Game, which most assuredly will occur. It will give you ultimate piece of mind. Sure, the anguish of a defective check disc may still come a-knockin', but the presence of the working DVD should a long way to rightfully deflect the blame to where it belongs.
1) Two variables are compared in bitwise operations. 2) Subpictures can be subtitles or menu overlays.
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