DVD-Video discs typically contain programs such as feature films, interactive games, or video reference materials like encyclopedias. The end user can play back those programs on a DVD-Video player or on a DVD-ROM-equipped computer. Some of the features of DVD-Video include support for multiple languages, parental control, different camera angles, and closed captioning.
This article discusses the unique features of DVD that are not available in pure MPEG-2 (its parent format) and outlines the interfaces and methods DirectShow provides in support of those features.
DVD-unique features include the following:
Title vendors can create feature-rich applications by taking advantage of these DVD-Video features.
Note: This release of DirectShow supports DVD-Video. It does not support pure MPEG-2.
See Additional DVD Resources on the Web for a list of DVD resources on the Web.
Contents of this article:
DVD Interfaces
DirectShow provides the following DVD-related interfaces.
Interface | Purpose |
IDvdGraphBuilder | Allows the DVD application writer to easily build a filter graph for DVD-Video playback. |
IDvdControl | Controls the playback and search mechanisms of a DVD-Video disc that contains one or more video movies. |
IDvdInfo | Allows an application to query for attributes of available DVD-Video titles and the DVD player status. It also allows for control of a DVD player beyond Annex J in the DVD specification. |
Later sections of this article group methods from these interfaces into functional categories.
DirectShow also provides a number of events. See DVD Events for more information.
DVD Control Data Structure
DVD-Video contains a nested hierarchy that provides search capabilities at several levels in the DVD data. This nested "control data" points to the real video and audio data. The following table outlines the structure of the control data for a DVD-Video volume. Each DVD volume can contain from one to 99 video title sets, which can contain one or more titles, which can contain one or more program chains. This nested structure continues to the smallest unit, which is the "pack." DirectShow provides seeking capabilities for DVD at three distinct levels, as outlined in Seeking in DVD.
DVD-Video Volume Structure
Control Data | Description |
Video Title Set (VTS) | Collection of movies. A single volume can contain one to 99 video title sets. |
Title | Individual movie. This may be a simple linear movie, consisting of one program chain, or it might consist of several program chains. |
Program Chain (PGC) | A collection of programs (often chapters in a movie). |
Chapter/Part of Title (PTT) | Collection of programs. Can delimit scenes or provide optional scenes from which to choose. Possible options include different ratings, camera angles, or a different storyline. |
Program (PG) | Collection of cells, which normally make up a scene. |
Cell | Collection of Video Object Units. Typically all the video and audio data from a certain number of Video Object Units. |
Cell-Part | Stream of data (multi-angle only). |
Video Object Unit (VOBU) | Usually half a second of video. |
Pack | 2KB of data, consisting of only one media type (such as video or audio). |
Pure MPEG-2 supports only the title and pack from the list above.
DVD Features
This section outlines features specific to DVD-Video and lists the DirectShow methods that provide these features.
Seeking in DVD
DirectShow allows you to seek at several different levels within the DVD content. Since pure MPEG-2 supports only title and pack control data, it does not provide the flexibility in seeking that DVD does.
Seeking Level | Control Data | IDvdControl Methods |
Title Seeks | Video Title Set (VTS), Title, Program Chain (PGC) | TitlePlay |
Chapter Seeks | Chapter/Part of Title (PTT), Program (PG), Cell | ChapterPlay (specifying title and chapter number), ChapterSearch (search for a chapter within the same title), PrevPGSearch, TopPGSearch, NextPGSearch |
Time Seeks | Cell-Part, Video Object Unit (VOBU), Pack | TimePlay (start playing specified title from specified time), TimeSearch (start playing from specified time within the same title) |
Subpicture
Subpicture is an extra media type that is decoded and alpha blended. The data on the alpha channel could be text for closed-captioning, buttons to provide a user interface, menus, subtitles, credits, and so on.
Methods relating to subpicture include the following:
Multiple Language Support
DVD-Video provides support of up to eight audio tracks to accommodate various languages. It also supports text in different languages for statistics related to the DVD title such as cast, crew, or title.
Methods relating to language support include the following:
Variable Speed Play
DirectShow provides variable speed play through the IDvdControl::ForwardScan and IDvdControl::BackwardScan methods:
Consumer DVD Interactivity
The consumer of a DVD title can interact with the title by selecting and activating buttons, displaying menus, and using the mouse to select and activate buttons.
Methods relating to consumer interactivity include the following:
Seamless Video Angle Change
DVD-Video supports up to nine camera angles. These angles can be completely independent video streams, or different camera angles of the same scene. The fast seeking of the DVD disc allows switching angles seamlessly.
Methods relating to video angles include IDvdControl::AngleChange and IDvdInfo::GetCurrentAngle.
Parental Control
Parental control provides security for parents who want to prevent children from viewing certain types of content. Content might be authored at a particular level, or might contain the same scene shot at different rating levels to provide a viewing alternative for children.
Methods relating to parental control include the following:
Additional DVD Resources on the Web
The following list contains links to a few of the Web sites that provide DVD information. Search the Web for other DVD resources. Note that most of these external links point to servers that are not under Microsoft's control. Please read Microsoft's official statement regarding other servers.
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