2/24/2008 9T6WP
BCM7405
Preliminary Hardware Data Module
Functional Description
06/29/07
Bro a d c o m C o rp o r a ti o n
Page 1-44
Video and Graphics Display
Document
7405-1HDM00-R
G
RAPHICS
S
UBBLOCK
D
ESCRIPTION
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).
