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DVD Authoring with Adobe Encore DVD
A Professional Guide to Creative DVD Production and Adobe Integration
By Wes Howell
Elsevier ScienceCopyright © 2004 Elsevier Inc.
All rights reserved.
In this chapter, we are going to go over the elementary considerations of a DVD author. If you are new to DVD authoring, then this is a great starter. If you are a seasoned pro, we are optimistic that there are a few new tricks you can pick up along the way. We'll talk about the different types of DVD media, DVD formats, and what to think about while you are planning your project.
Many books go into extreme detail, covering the most technical and complicated aspects of DVD. There's even a big, thick book that costs $5,000.00 and is guaranteed to suck at least a good year from your life. (This is the DVD specification, or DVD spec.) This rigid standard is what keeps everyone on the same page. It also covers every technical detail you could imagine.
Encore is about making DVD authoring simple, incorporating many of the most complicated aspects of authoring "under the hood." Encore doesn't require you to be a programmer or a full time author; instead it sticks with a graphical concept that makes advanced functions simple and accessible. Likewise, the goal of this book is to present some of this information, helping you become productive without bogging you down with too many details. We'll refer to the DVD spec from time to time, but our goal is to offer the most clear, concise, and pertinent information that will help you become proficient and productive with Encore.
If you are truly interested in the most technical aspects of DVD production, or if you want to expand your knowledge of the DVD standard, there are several good books on the market. We'll include these and some other good resources in Appendix B.
Now let's get down to business.
Disc capacity and data rate
Organizing and planning your project
With the introduction of Encore, Adobe finally brings affordable and professional DVD authoring to the PC. Many of Encore's features are offered at a small fraction of what they would have cost a few years ago. DLT support, copy protection, and "under the hood" scripting capabilities establish Encore as a serious player in the world of DVD software.
Encore is an even better value for those of you who already use Adobe applications. Taking advantage of the natural synergy between applications, Encore bridges the gap between Photoshop, After Effects, and Premiere, opening up new creative opportunities and workflows not available on any other platform.
It's an exciting time to be a DVD author. Modern tools, such as Encore, have brought the power of desktop DVD authoring to anyone with a PC and a desire to master the technology. It's getting cheaper, faster, and easier too! Can't complain about that.
Disc Capacity and Data Rate
Capacity and data rate are two of the most important concepts in DVD authoring. It's only fitting that we cut right to the chase and address these right from the start.
By default, Encore automatically sets compression parameters according to the size and quantity of assets used in the project. These automatic transcoding features will automatically compress non-DVD compliant content, preparing them for use on the finished disc. This takes a lot of the guesswork out of producing a DVD and is a good starting point for beginning authors.
Encore also provides access to all compression settings, allowing authors direct control over bitrate and other important details.
There are many advantages to specifying your own settings. Taking control over the encoding process can aid project management, provide more control over bit allocation, and improve the quality of video content. Although Encore is a very intuitive program, it cannot read minds to determine which assets require more attention than others.
The capacity is the maximum amount of data that can be stored on the DVD. Total available capacity will vary by project and is also dependent on the delivery medium. Encore provides several templates including options for Single-Layer or Dual-Layer DVDs as well as options for general and authoring media.
Most readers will be using general purpose DVD-R / DVD+R media, which have a capacity of 4.7 GB. This is the most popular consumer format. Another popular format offering increased capacity, DVD-9, is available from professional replication houses and is typically used for most commercial movies. DVD-9 can store up to 8.54 billion bytes or 7.95 (computer) gigabytes. There are many other formats that offer multiple layers (on one side of the disc) as well as dual layer, dual sided discs with a maximum capacity of 15.9 gigabytes. These capacities will only continue to increase as new technologies are introduced.
The data rate, or bitrate, refers to how many bits are utilized, measured in bits per second, to playback or encode streams for the DVD. This figure can represent individual streams, such as audio or video, or the final multiplexed DVD-video stream that includes all audio, video, and subpicture content.
According to the DVD specifications, the maximum combined bitrate for DVD is 10.08 Mbps. This includes all video, audio, subtitles, subpictures, etc. The maximum bitrate for video alone is 9.8 Mbps.
Most authors will find themselves working with average combined bitrates between 5 and 7 Mbps.
Bitrate is specified by the author when encoding assets. Higher bitrates produce higher quality content, so most authors strive to set the bitrate as high as they can. Unfortunately, higher bitrates take up more disc space. The goal is to find the perfect balance between quality and file size. To find the target bitrate when encoding video streams, we simply take the available capacity and divide by time. (See section on non-video assets.)
In order to determine data rate, first we need to know the maximum capacity of the disc. For example, is the project destined for a single or dual layer, single- or dual-sided disc? DVD-5, DVD-9, DVD-18?
Once disc capacity is established, we need to determine how many bits all the different assets in the project will require. The amount of space that non-video assets require also needs to be taken into consideration before the video encoding rate (bitrate) can be determined.
Here are a few questions to help insure that non-video assets are accounted for:
How much space will is needed for DVD-ROM content (i.e., screensavers, PC files)?
How much space is required for menus? Will there be motion menus?
How many audio tracks will be used? How many languages will be used on the disc?
Will the disc require subtitles? If so, How many?
After these factors are taken into account an additional reserve of 5% to 7% should be deducted to compensate for overflow and disc file structure.
Finally, the remaining bits can be used to encode the main video streams for the project.
If all of this seems a bit overwhelming at this point, don't worry. We'll cover these topics in greater detail in Chapter 3.
Determining the perfect bitrate is somewhat of a balancing act. A small project that doesn't utilize all of the available space on a disc might not be living up to its potential in terms of picture quality. In many cases, a higher bitrate could increase video quality substantially. On the flip side, a project that is too big won't fit on the disc and could require re-encoding and re-authoring. Not only can a few minutes of planning improve the quality and flow of your production, it can also eliminate hours of wasted time, money, and frustration. To learn more about calculating the perfect bitrate, see Determining Bitrates in Chapter 3.
DVD formats can be divided into two separate categories: physical and logical formats.
The physical format refers mainly to how the disc is physically configured. Every DVD will have a specific format. Some of the most common physical formats are: DVD-ROM, DVD-R, DVD+R, and DVD-RAM.
The physical format also refers to how the disc is constructed. The main consideration for most authors will be what type of discs are supported by their DVD burner. Some burners were designed to burn DVD-R media, while others support a rival format, DVD+R. This is becoming less of an issue as modern burners begin to support multiple formats. Below, several common physical formats are listed.
DVD-ROM refers to both the physical structure as well as the file system used on the disc. In other words, DVD-ROM can be considered both a physical and logical format. DVD-ROM is the foundation of DVD and includes several variants listed in this section. Although DVD-ROM can hold virtually any kind of digital information, variants such as DVD-Video and DVD-Audio are logical formats limited to specific data types that cater to video and audio playback.
DVD-R is a write once, read many times format adopted by the DVD consortium that allows consumers and professionals alike practical access to the DVD spec. Two types of media are available—General and Authoring. 4.7 GB general media discs are the most common. These are the discs supported by devices such as the Pioneer DVR-A04, A05, and A06 burners. Authoring media, designed as more of a professional format, requires specific hardware that supports it, such as the Pioneer DVR-S201. The authoring format has become less relevant as most authors will find DLT to be a superior format for delivery to a duplication facility. DLT is less expensive, supports copyright protection, and is also more reliable as a master.
DVD-RW allows the author to rewrite (overwrite) content to the same disc up to 1,000 times. This format is often used to test projects while eliminating the expense of "wasting" write once, DVD-R media. Most new set top players can read DVD-RW; however, the discs are less compatible than regular DVD-R media. So keep this in mind when doing final compatibility tests.
Panasonic and Hitachi have championed DVD-RAM, another DVD format. DVD-RAM allows for multiple session recording and is recognized as a great format for tasks such as data backup and archiving. Unfortunately, it has never enjoyed the same compatibility and acceptance as the DVD-R and DVD+R formats.
Sony and Phillips, promising better compatibility than the existing DVD-R format, introduced DVD+R. This format is similar in many ways to DVD-R, offering write once capability and a 4.37 GB maximum capacity. While many people swear by this new format, the same can be said for die-hard proponents of the DVD-R format. It's not readily apparent which format is superior. Most users find the two formats very comparable. Realistically, other factors such as media quality and player performance are more important. In addition, most newer burners such as the DVR-A06 and the Sony DRU-510 support both DVD-R and DVD+R formats.
Comparable to DVD-RW, the DVD+RW is in accordance with the DVD+R format, adding the ability to write multiple times to the same disc.
Logical format refers to the type of data that a DVD contains.
The DVD-ROM file structure can hold just about any type of digital information. This includes files that are created by and intended for use on a computer. DVD-ROM discs can hold many different types of data including audio and video content. This format is quickly replacing CD-ROM in the computer industry.
This variant holds video that is formatted for use with a set top player or a computer with a DVDROM drive and a software player. DVD-Video can deliver full screen 720×480 pixel frames at 23.97 or 29.97 frames per second in NTSC, or 720x576 pixel frames at 25 fps in PAL. Progressive NTSC sources can be displayed on progressive displays or can be converted inside the player to a 29.97 fps interlaced signal for playback on interlaced sets. NTSC players also support a process known as 3:2 pulldown that converts 23.976 progressive content into 29.97 interlaced video. This process is commonly used to transfer film to video for NTSC playback. DVD-Video discs contain a Video_TS folder, and some may also include an Audio_TS folder; however, this is not required.
As the name implies, Hybrid DVDs contain a mix of information. A Hybrid disc contains DVD-Video files and a file structure that accommodates playback on a set top player. Hybrid discs also contain content that is intended for use on a PC, such as supplemental information, HTML pages, or screen savers.
DVD-Audio was introduced as a replacement for the audio CD. Taking advantage of increased capacity, DVD-Audio offers much higher fidelity provided by higher sample rates and bit depths. Audio CDs offer 44.1 kHz, 16-bit audio while DVD-Audio can support 24-bit audio with sample rates as high as 192 kHz. Encore does not support DVD-Audio at this time.
There are several different factors that contribute to the overall compatibility and playback of burned DVD media.
Excerpted from DVD Authoring with Adobe Encore DVD by Wes Howell. Copyright © 2004 by Elsevier Inc.. Excerpted by permission of Elsevier Science.
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