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AMD Geode™ SC2200 Processor Data Book
Video Processor Module
32580B
7.2.2.2
Horizontal Downscaler with 4-Tap Filtering
The Video Processor implements up to 8:1 horizontal
downscaling with 4-tap filtering for horizontal interpolation.
Filtering is performed on video data input to the Video Pro-
cessor. This data is fed to the filter and then to the down-
scaler. There is a bypass path for both filtering and
downscaling logic. If this bypass is enabled, video data is
written directly into the line buffers. (See Figure 7-8.)
Filtering
There are four 4-bit coefficients which can have pro-
grammed values of 0 to 15. The filter coefficients can be
programmed via the Video Downscaler Coefficient register
(Memory Offset 40h) to increase picture quality.
Horizontal Downscaler
The Video Processor supports horizontal downscaling. The
downscaler can be implemented in the Video Processor to
shrink the video window by a factor of up to 8:1, in 1-pixel
increments. The downscaler factor (m) is programmed in
the Video Downscaler Control register (Memory
Offset 3Ch[4:1]). If bit 0 of this register is set to 0, the
downscaler logic is bypassed.
The horizontal downscaler supports downscaling of video
data input format YUV 4:2:2 only.
The downscaler supports up to 29 downscaler factors.
There are two types of factors:
•
Type A is (1/m+1). One pixel is retained, and m pixels
are dropped. This enables downscaling factors of 1/16,
1/15, 1/14, 1/13, 1/12, 1/11, 1/10, 1/9,1/8, 1/7, 1/6, 1/5,
1/4, 1/3, and 1/2.
•
Type B is (m/m+1). m pixels are retained, and one pixel
is dropped. This enables downscaling factors of 2/3, 3/4,
4/5, 5/6, 6/7, 7/8, 8/9, 9/10, 10/11, 11/12, 12/13, 13/14,
14/15, and 15/16.
Bit 6 of the Video Downscaler Control register
(Memory Offset 3Ch) selects the type of down-
scaling factor to be used.
Note:
There is no vertical downscaling in the Video Pro-
cessor.
Figure 7-8. Horizontal Downscaler Block Diagram
Bypass
4-Tap
Horizontal
4x4
Downscale
Video
Input
Filtering
Coefficients
Downscaler
Factors
To Line
Buffers
Summary of Contents for Geode SC2200
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Page 16: ...16 AMD Geode SC2200 Processor Data Book Overview 32580B...
Page 70: ...74 AMD Geode SC2200 Processor Data Book Signal Definitions 32580B...
Page 350: ...366 AMD Geode SC2200 Processor Data Book Debugging and Monitoring 32580B...
Page 422: ...440 AMD Geode SC2200 Processor Data Book Electrical Specifications 32580B...