Overview of the DVD Production Process

As with similar processes for other interactive multimedia formats, the preliminary design steps for DVD-Video include the following:

Creating a project plan, such as a script or flowchart, that illustrates the program flow of the DVD. The plan will define the content that is included, the menus that are needed, and the destination or consequence of activating each option on every menu (e.g. a given button begins playback of a given video clip, while another button takes you to a menu to set the soundtrack language).

Creating a list of the individual assets (video, audio, stills and subpictures) that make up both the content and the menus defined in the plan.

Preparing the assets in a way that makes them usable within the framework of the DVD-Video specification.

Once the planning is complete and the assets are prepared, ReelDVD makes the final authoring steps surprisingly fast and easy. These steps are explained in detail in Asset Import and Authoring and Simulation and Writing. They include:

Adding the video assets

Adding audio streams to the video

Adding captions or subtitles

Inserting chapter breaks

Creating slide or still shows

Creating menus, and defining menu buttons and the button paths

Adding navigational commands to menus and other assets

While it is easiest to explain these authoring steps in a linear order, the actual order in which they are executed is generally a matter of individual preference. At any stage in the process, you can simulate playback of your project or of individual assets using the built-in Preview window.

Project Planning Rules

The DVD specification spells out exactly what kinds of data can be included in a DVD-Video title, and how that data is organized. ReelDVD also makes certain additional assumptions about the source assets used in a project. To ensure that a project will play back correctly on a DVD player, it’s crucial to keep these rules in mind during title planning and development. The rules include:

No Mixing of Video Encoding Types in a Project

DVD-Video supports playback of motion video and still images encoded in either the MPEG-1 or MPEG-2 video format. But it is not allowed to mix the two video formats within a single project. (It is, however, acceptable to vary the encoding parameters—bit rate, for instance—of visual content within a project.) Once video assets of one format have been imported into a project, ReelDVD will no longer accept assets of a conflicting format for that project.

No Mixing of Video Frame Sizes in a Project

All of the motion video and still images in a project must have the same frame size Acceptable sizes for NTSC are 352x240, 704x480, or 720x480; for PAL they are 352x288, 704x576, or 720x576.

No Mixing of Video Aspect Ratios in a Project

All of the content in a project must be of the same aspect ratio, either 4:3 Standard or 16:9 Widescreen. It is not possible to mix content of different aspect ratios. Once video assets of a given aspect ratio have been imported into a project, ReelDVD will no longer accept assets of an alternate aspect ratio for that project.

No Pan & Scan Video

ReelDVD does not support the use of Pan & Scan video. Because few video encoders are capable of creating Pan & Scan content, this constraint rarely has any practical impact.

No Mixing of Audio Formats or Bit Rates in a Stream

ReelDVD supports up to eight audio streams per Track, each of which is assigned a number (1–8). Once the audio format and bit rate of a given stream is defined in any Track in the project, the audio streams of the same number in all other Tracks of the project are reserved exclusively for audio in that same format and bit rate. For example, if the audio format of the first source-file assigned to stream #2 in any Track is Dolby Digital (2/0) encoded at 192Kbps, then whenever audio stream #2 is used in any other Track it must use Dolby Digital (2/0) encoded at 192Kbps. (This means it is not possible to include both Dolby Digital and Linear PCM in the same stream number in a project.) ReelDVD will generate an error message if you attempt to mix audio formats or bit rates in a stream.

No Gaps in Audio or Subpicture Stream Numbers

In each Track, audio and subpicture streams must be used in ascending numerical order. In other words, for each stream type (audio or subpicture), a stream of a given number can only be used if the Track also uses streams of a lower number. For example, to use audio stream #3, you must also have data in streams #1 and #2. In situations where no actual data is needed in a given stream position, placeholder data (a few seconds of silence or a single transparent subpicture) can be used to comply with this requirement. During authoring, ReelDVD assumes that any gaps in stream numbers will be filled with additional stream data before the project is compiled. If gaps remain when the Make Disc operation is started, ReelDVD will abort the process and generate an error message.

Linear PCM or Dolby Digital Audio Data Required for NTSC Projects

If a project using NTSC video contains any audio at all, the DVD specification requires that it contain at least one stream of audio in Linear PCM or Dolby Digital. The project can also contain an optional stream in MPEG Audio, but playback support for MPEG audio is not required of NTSC DVD players. If an NTSC project is created with only MPEG Audio, ReelDVD will abort the layout process and generate an error message.

Note that PAL DVD players are required to support all three audio formats, and therefore one is allowed to create a PAL title using only MPEG Audio. However, due to reports of players that may not play back MPEG Audio correctly, its use is not widely recommended.