From the time your video content has all been shot, acquired, and compiled, your post-production efforts are likely to include thoughts of DVD. DVD is an inexpensive, efficient way to deliver your work to your audience, whatever the content and purpose. Though you may have mastered some of the intricacies and challenges of production, getting your work onto DVD requires attention to some technical considerations that may be unfamiliar to you.
Taking the Long View
The individual steps required to go from a digital video production to a DVD aren’t particularly complicated, but there are decisions with technical ramifications at each step in the process. From the proverbial 20,000 foot view, here are the primary stages involved in the process, each of which will be discussed in more detail.
- Plan the Approach. A DVD can be as simple as a video that just starts playing when you insert it in a player, or a complex, multi-layered interactive piece with many chapters, options, and extras. Know going in what level of complexity best suits your work (and your budget). This will help the authoring service determine what assets are needed and what the costs will be.
- Collect the Assets. Decide which DVD features you want to use and collect the assets needed for authoring them. For example, if you want to include a Director’s Commentary option, create a time-coded audio track to submit with the running commentary. Or, if your feature will have subtitles, you’ll need a script for each language you want to support. Similarly, make sure you have necessary graphics assembled for packaging, DVD labels, and menus.
- Submit Content in Appropriate Formats. The best results, as is the case with most
kinds of digital production, are achieved if you start with the highest resolution content. For hand-off to an authoring house or replication service, the closer to uncompressed source material, the better.
- Communicate Your Project Intentions. The more clearly you communicate your intentions for the DVD menus, features, and design to the authoring professionals involved, the less chance of missteps along the way. Too much information is better than too little.
- Check and Verify the Results. Many authoring services provide interim proofs or PDFs of packaging, navigation menus, and label designs. Just prior to replication, you’ll typically get a proposed final master disc for approval. Don’t skimp on this vital step. Check and verify every second of disc content.
Planning the Approach
From a multitude of options, you need to narrow your approach and decide the scope and parameters of the content for your DVD project. At the very least, you have a central video or slide presentation that forms the core of your project.
To the core digital content, you can add subtitles in different languages, a commentary track, extra features, additional material for computer DVD-ROM users, reference materials, surround-sound audio, and other bells and whistles. As would be expected, each additional feature you specify will require additional time for the authoring service to implement and add to your costs. And for each addition of this sort, you need to supply the digital content in appropriate formats.
If you’re knowledgeable and technically fluent, you can do all of these tasks yourself using a tool such as Apple’s DVD Studio Pro and then submit a DVD-R master or DLT tape to go directly to replication. Be forewarned, however, if you’re new to the process there are many potential pitfalls and a host of technical issues to consider. Until you gain some experience with the medium, for your first DVD at least, it might be wise to enlist the services of a professional authoring house.
Once you’ve determined the features you want to have on the DVD, catalog all of the assets to be handed off to a replication service, as described in the next section.
Collecting the Assets
The best results for a DVD project will be achieved when you store and submit all digital assets in the highest resolution file formats possible. You want to avoid lossy compression codecs, compressed photographic images, low quality audio files, and similar compromised content.
To produce a DVD, digital video content is encoded for delivery on disc and then decoded when played back on a computer or DVD player. Heavy compression on top of compression usually results in artifacts or unsatisfactory quality, so minimize the use of compression in your digital content at every stage in the process.
You can’t entirely avoid compression, since all digital video undergoes some compression from the time it is initially captured on videotape. Depending on the format, this might be as low as 3.3:1 for Digital Betacam MPEG IMX to 5:1 for miniDV. The higher-end formats (such as Digital Betacam) typically support more detailed color sampling (4:2:2 in the case of Digital Betacam) versus the more modest color sampling used for miniDV, 4:1:1. Consequently, the higher end formats deliver richer color detail, better suited to DVD.
Replication and authoring services sometimes have different requirements for materials that are submitted, so check with a contact or sales representative to ensure you’re gathering materials in a format suitable for submission.
As a guideline for preparing assets, the following table lists common acceptable file formats to submit materials for DVD authoring:
The hand-off of digital media assets and explanation of what to do with them is a vital step in the authoring of a DVD. One technique that is often employed by authoring houses and replication services is to have the materials consolidated on an external hard disk drive and then shipping that drive to the service. This has the advantage of providing all content on one easily accessible device, as well as giving you the ability to organize the content in named folders that let the authoring service quickly identify and begin using the files.
Because you will be transferring extremely large files, recordable disc formats—such as DVD-R and DVD+R—may not have the capacity to store your material for submission. For example, digital video in NTSC format typically generates files of around 101GB (10-bit uncompressed at 720×486) for each hour of material. A single DVD-R may be able to store content for submission if you have a 15-minute marketing presentation, but—for longer movies and training videos—purchasing an external drive that you can ship to the authoring house provides a better solution.
Before storage system costs dropped in price dramatically, Digital Linear Tape (DLT) was the standard method for supplying replicators the Data Description Protocol (DDP) files to use when making a DVD. Many services still rely on this durable, reliable storage medium, but it is usable only if you are submitting a final DDP image (which the replication service uses to make a DVD glass master); DLT is not suited for delivering a collection of files to an authoring service.
If you are ready to submit a DDP image to a replicator and you don’t have a DLT drive, software such as GEAR PRO Mastering lets you write DDP images to a variety of storage devices, including hard disk drives, 4mm tape (DAT), or even directly to the replicator using FTP. Regardless of how your files are transferred, if your content will be mastered to a dual-layer DVD, talk with your replication service or authoring house to ensure that the layer break will be placed at the appropriate location. If you plan on using copy protection on the DVD, this also needs to be discussed before files are submitted.
The more professional authoring services can routinely enhance your video content with color correction and other types of enhancements. If you need these services, be sure to submit the video on hard disk, tape cartridge, or video cartridge (rather than as a finished DVD). It’s possible to break apart the video from a DVD into elementary streams and raw files for further processing, but it’s time consuming (and expensive) to do this. Also, because the files extracted from the DVD have already been compressed, the quality of the video content will suffer. The best practice is to return to the original tape masters if any kind of video enhancement is needed.
Communicating Your Intentions
At the authoring stage, all of the files you’ve submitted need to come together in a structured way to create a DVD that plays as intended. This is the point where clear communication is vital to obtaining the results you want, whether you convey your intentions in person to a representative or complete a printed or electronic form that describes chapter breakdowns, feature lists, file uses, and other essential data.
The more detailed and organized you are, the less opportunity for unexpected glitches or problems to creep into the process. If you don’t understand any part of this process, now is the time to ask questions. A customer-oriented authoring service won’t rush you through this process and will patiently walk through the details and explain all the processes to your satisfaction.
Video content on a DVD gets encoded to the MPEG-2 file format for disc storage and playback. MPEG-2 can compress the video content to greater or lesser levels, but obviously the more compression you use (to fit more video content on disc), the lower the video image quality. At some point, usually when you get beyond trying to fit 90 minutes of content on disc, the lowering of quality becomes unacceptable. By authoring the content for a dual-layer disc (DVD-9), you can overcome bandwidth limitations and obtain higher quality video for longer movies.
There is an art and science to video encoding, so pick a service you trust with experience in this area. Commonly, video content that is submitted on tape cartridge is handled using a hardware encoder, a dedicated device that can achieve consistently high results. Video content submitted on disc or on a hard drive can typically be handled using either hardware or software encoding, depending on the equipment in use at the authoring facility.
Software encoding is frequently employed when the video content has frames that change frequently, such as action movies and animated content. By increasing the time the computer uses to encode each frame of the movie, more precise results can be obtained and difficult imagery can be handled successfully. Discuss the tradeoffs and the nature of your video content with your chosen service to determine which form of encoding would be best and whether a one-layer or two-layer disc would be optimal for your DVD project. Keep in mind that each custom (non-automated) service that you request will likely bear an additional cost.
The cost of the authoring service will typically vary from about $400 to $2,400, depending on DVD features selected and the individual vendor’s business practices. As might be expected, the more ambitious your intentions, the higher the cost. However, a basic package that includes two individual DVD menus with a Play All selection and individual scene selection with 10 or 12 chapters can be found at the lower end of the cost scale. The expertise of the selected vendor and their experience in this field should be one of your primary considerations.
Verifying the Results
Once you turn the authoring service loose to start work on your DVD project, you will receive interim updates and project samples for approval or correction. This process is handled in a number of different ways, depending on the service. Craig Hanna of The Authoring House, a division of Disc Makers, describes the process this way: “Once the customer sends in all their information – the video, the chapter points, and any kind of artwork, we base our design on the packaging. A lot of times the customer has already put together their packaging or uses our Design Studio to do their packaging. We repurpose those materials or that design for the DVD menu design, which helps provide a unified look to the package. Then, we make a PDF of the design and send that by email. If we are doing a motion menu, we email a Flash file to show the functionality of the motion on the menu. Once they approve their menu, we put together the DVD and send the customer a DVD-R proof for their approval.”
The proof you receive from an authoring service is a final check – an opportunity to inspect the DVD material and navigation to ensure that everything meets your specifications and that there are no audio glitches or video defects. When you receive the proof, check all menu functions and chapter entry points carefully, as well as screening all the video content from beginning to end. Is everything in sync? Do the colors look right? Are there any artifacts appearing in the frames?
If your project includes subtitles or director commentary, run through it again, listing each problem and noting where it occurs. Usually, problems can be corrected following a brief phone call or email message. Expect that you may have to view at least two proofs and maybe as many as three or four to get the DVD exactly right. You’ll be rewarded for your concentration and effort at this stage with a much cleaner, much more professional final product.
Lee Purcell writes about technology topics – including ray tracing, parallel computing, alternative energy, and open-source software – from Arlington, Vermont. Visit his blog at lightspeedpub.blogspot.com for spirited insights into energy advances.