2/24/2008 9T6WP
BCM7405 Preliminary Hardware Data Module
Functional Description 06/29/07
Broadcom Corporation
Page 1-44 Video and Graphics Display Document 7405-1HDM00-R
GRAPHICS SUBBLOCK DESCRIPTION
The Memory-to-Memory Compositor interacts directly with memory only. There is no real-time processing of graphics (apart
from the graphics feeder in the video block). This allows the graphics system to be divorced from the video that reduces the
real-time scheduling (RTS) requirements. This real-time scheduling was becoming more and more restrictive as more
graphics features have been added to the system requirements.
The purpose of a compositor is to manipulate memory in an efficient manner—where the memory contains graphics or other
data that displays. The simplest of these operations is a memory-to-memory DMA function (a.k.a. copy BLT). More complex
operations include ROP, blend, and/or scale options.
Features
• Picture Size: Up to 8191 pixels per line and 8191 lines per picture for both input and output.
• Pixel Format: Accept and supply many raster-ordered formats. Each input and output can be stored in different formats.
• Scaling Capability: FIR filters available for both upscale and downscale. To improve vertical filtering, a vertical mode of
operation has been introduced to facilitate anti-flutter filtering and other advanced visual filtering algorithms.
• Non-real-time operation: The concept of using the compositor to handle the graphics processing is to divorce this
operation from the real-time display and compositing of the resulting video.
• Processing performance of up to one pixel per clock
• Color Keying
• Color Matrix
• Scaler
• Compositing operations can also be used to handle format conversions (such as replacing ARGB4444 with AYUV8888
data)
CLUT inputs cannot be converted to another CLUT (the reverse look-up table is not available).
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