VMR Renderless Playback Mode

This topic applies to Windows XP Home Edition and Windows XP Professional only.

In renderless playback mode, the VMR does not do its own rendering, but instead uses a custom Allocator-Presenter supplied by the application. This mode is useful for game writers, and HTML+TIME and other types of applications that do sophisticated video effects. Renderless playback mode enables applications to create and control their own DirectDraw surface, and/or to obtain access to the video bits at presentation time.

In renderless playback mode, the Application:

• Manages the playback window.
• Allocates the DirectDraw object and the final frame buffer.
• Notifies the rest of the playback system of the DirectDraw object being used.
• “Presents” the frame buffer at the correct time.
• Handles all Resolution Mode, monitor changes and “surface losses” – advising the rest of the playback system of these events.

The VMR:

• Handles all timing related to presenting the video frame.
• Provides quality-control information to the application and the rest of the playback system.
• Presents a consistent interface to the upstream components of the playback system, which are not aware that the application is providing the frame buffer allocation and performing the rendering.
• Provides any mixing of video streams that may be required prior to rendering.