ARRIS Enterprises, Inc. Confidential Information

Graphics Renderer Control

Compared to earlier versions of KreaTV we have tried to give the graphics rendering in the application layer more freedom to control different aspects of the graphics handling, e.g. whether to use double buffering and how graphics and video are composed on different outputs. This also means that more responsibilities are put on the application layer.

Graphics composition: No graphics composition is performed in KreaTV at all. This means that the application layer itself must compose its own graphics with subtitles, for instance. This gives the application freedom to decide the z-order of different graphics components, including subtitles.
Hole punching: The graphics rendering engine in the application layer is responsible for "punching" a transparent hole in the graphics to make video visible when a video layer has been set up. This makes it possible for the application to control the level of transparency and which parts that shall be transparent, e.g. to set up rounded or fuzzy corners.
Output handling: With KreaTvGfx the application layer can decide to show different graphics and/or video on HD and SD displays. This also means that the application layer is responsible for "flipping" graphics with correct size on both outputs.
Double buffering: The graphics rendering engine is responsible for doing double buffering if needed. It may choose to not do so if smooth animations are not needed or if the amount of graphics memory is limited.
Blitter: With KreaTvGfx the graphics renderer is able to use the blitter to perform copy and fill operations. This gives a significant performance boost if used wisely (e.g. not blitting many small portions).
Alpha blending: With KreaTvGfx the graphics renderer is able to use alpha blending to achieve transparency effects with graphics on top of graphics, or graphics on top of video.
Pixel formats: With KreaTvGfx the graphics renderer can use different types of pixel formats suitable for different purposes, e.g. colour look-up tables (CLUT) for images with few colours.