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 1-40
Video and Graphics Display
Document
7405-1HDM00-R
AVC/MPEG-2/VC-1 Feeder
The AVC/MPEG-2/VC-1 feeder supports a number of frame buffer formats. In addition, a number of frame buffer formats
commonly used by software codecs are included and registered in Microsoft as Four-Character Code (FOURCC). The scope
is limited to 4:2:0 and 4:2:2 formats only, and other formats are not supported (such as 4:4:4). The AVC/MPEG/VC-1 feeder
is capable of HD resolutions and can support pan-scan operations.
The following sections describe the following frame buffer formats.
Advanced Video Decoder Format
The Advanced Video Decoder (AVD) uses the linear image format. Image data is stored in DRAM in a striped format i.e.,
slicing an image into a series of equal-sized vertical strips and then tacking the strips together. The height of a stripe is a
programmable parameter, this must be at least as large as the 'tallest' image that will be stored in the buffer. It is generally
made a little larger than that to achieve optimal DRAM bank alignment. Though the stripe width is programmable but feeder
supports only 64-bytes stripe width. A picture in the AVD format contains two separate arrays, one is for luma (Y)
components, and the other is for chroma (Cb and Cr) components. Chroma components are stored Cb/Cr interleaved, with
the same stripe width and a programmable stripe height.
Packed YUV
For a 4:2:2 picture, pixels are paired together as CbYCrY quadruplets. They are organized in a raster scanning order. There
are a number of permutations within a quadruplet. They are represented in FOURCC as:
•
CbYCrY (UYVY)
•
YCbYCr (YUY2)
•
YCrYCb (YVY2)
Video Feeder
The Video feeder supports a subset of the number of frame buffer formats that the AVC/MPEG/VC-1 feeder supports. Its
scope is limited 4:2:2 formats only. Other formats are not supported (such as 4:2:0 and 4:4:4).
Packed
For a 4:2:2 picture, pixels are paired together as CbYCrY quadruplets. They are organized in a raster scanning order. There
are a number of permutations within a quadruplet. They are represented in FOURCC as:
•
CbYCrY (UYVY)
•
YCbYCr (YUY2)
•
YCrYCb (YVY2)
Graphics Feeder
The Graphics feeder only supports 4:4:4 or ARGB formatted graphics or video. Other format are not supported (such as
4:2:0 and 4:2:2). The 4:4:4 data requires that the data be stored in one of the following selections:
•
32-bit formats
-
AYCrCb_8888
-
YCrCbA_8888
-
ARGB_8888
-
RGBA_8888
•
17-bit format