Intel® 865G/865GV Chipset Datasheet - download.intel.nl - Intel

Functional Description5.4.3 Video EngineHardware Motion CompensationThe Motion Compensation (MC) process consists of reconstructing a new picture by predicting(either forward, backward, or bidirectionally) the resulting pixel colors from one or more referencepictures. The GMCH receives the video stream and implements motion compensation andsubsequent steps in hardware. Performing Motion Compensation in hardware reduces theprocessor demand of software-based MPEG-2 decoding, and thus improves system performance.The motion compensation functionality is overloaded onto the texture cache and texture filter. Thetexture cache is used to typically access the data in the reconstruction of the frames and the filter isused in the actual motion compensation process. To support this overloaded functionality thetexture cache additionally supports the following input formats:• YUV420 planarSub-Picture SupportSub-picture is used for two purposes; one is Subtitles for movie captions, etc., which aresuperimposed on a main picture, and another is for Menus to provide some visual operationenvironments for the user of the player.DVD allows movie subtitles to be recorded as Sub-pictures. On a DVD disc, it is called “Subtitle”because it has been prepared for storing captions. Since the disc can have a maximum of 32 tracksfor Subtitles, they can be used for various applications; for example, as Subtitles in differentlanguages or other information to be displayed.There are two kinds of Menus, the System Menus and other In-Title Menus. First, the SystemMenus are displayed and operated at startup of or during the playback of the disc or from the stopstate. Second, In-Title menus can be programmed as a combination of Sub-picture and Highlightcommands to be displayed during playback of the disc.The GMCH supports sub-picture for DVD and DBS by mixing the two video streams via alphablending. Unlike color keying, alpha blending provides a softer effect and each pixel that isdisplayed is a composite between the two video stream pixels. The GMCH can use four methodswhen dealing with sub-pictures. The flexibility enables the GMCH to work with all sub-pictureformats.5.4.4 PlanesA plane consists of a rectangular shaped image that has characteristics such as source, size,position, method, and format. These planes get attached to source surfaces that are rectangularmemory surfaces with a similar set of characteristics. They are also associated with a particulardestination pipe.5.4.4.1 Cursor PlaneThe cursor plane is one of the simplest display planes. With a few exceptions, this plane has a fixedsize of 64x64 and a fixed Z-order (top). In legacy modes, cursor can cause the display data below itto be inverted.Intel ® 82865G/82865GV GMCH Datasheet 173