MB86296 Datasheet, PDF (88/352 Pages) Fujitsu Component Limited. – PCI Graphics Controller Specification

FUJITSU LIMITED PRELIMINARY AND CONFIDENTIAL
8.2 Video Buffer
8.2.1 Data Form
The video capture unit of MB86296 “Coral-PA” accepts YUV422 video data primarily, but RGB video
data is also accepted via an internal RGB preprocessor which converts RGB to YUV422.
Captured pixels are stored in YCbCr format in graphics memory, 16 bits per pixel. The video data is
converted to RGB when it is displayed.
31
24 23
16 15
87
0
Y1
Cr
Y0
Cb
Y0,Y1
Cr,Cb
76543210
Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
C7 C6 C5 C4 C3 C2 C1 C0
8.2.2 Synchronous Control
Writing to the graphics memory of video image data and scan for a display are performed
independently. The graphics memory for video captures is controlled by the ring buffer system. It
displays the frame, when the image data for one frame can be preparing on a memory. When the
frame rate of a video capture differs from the frame rate of a display, the continuation display of top
omission or the same frame occurs.
8.2.3 Area Allocation
Allocate an area of about 2.2 frames to the video capture buffer. The size of this area is equivalent
to the size that considers the margin equivalent to the double buffer of the frame. Set the starting
address and upper-limit address of the area in the CBOA/CBLA registers. Here, specify the raster
start position as the upper-limit address.
To allocate n rasters as the video capture buffer, set the upper-limit value as follows:
CBLA = CBOA + 64 (n-2) × CBW
In addition, the head addresses of n+1 raster are 64n×CBW, and CBLA+2 raster becomes a buffer
domain. For reduced display, allocate the buffer area of the reduced frame size.
MB86296S<Coral-PA>
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Specification Manual Rev0.1