Intel 815 Manuel D’Utilisation
Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0
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15.4.6. Overlay Scale Factor Registers
These registers provide the scaling information that is used to specify the amount of vertical and
horizontal scaling. In the case of YUV formats, there are independent scale factors for Y and UV data to
compensate for the various formats that include sub-sampled UV data. Up or down scaling is set using
the bits of the command word. In the case of down scaling, the integer portion of the scale factor can be
up to three in the vertical and is assumed to be one in the horizontal.
horizontal scaling. In the case of YUV formats, there are independent scale factors for Y and UV data to
compensate for the various formats that include sub-sampled UV data. Up or down scaling is set using
the bits of the command word. In the case of down scaling, the integer portion of the scale factor can be
up to three in the vertical and is assumed to be one in the horizontal.
15.4.6.1.
YRGBSCALE—Y/RGB Scale Factor Register
Memory Address Offset:
40h (R/W)
On-chip Reg. Mem Addr Offset:
30140h (RO; debug path)
Default Value:
00h
Access:
see address offset above
Size:
32 bits
31
20 19 17
16 15
14
3 2 1
0
Vertical Scale Factor
Y/RGB
Reserved Horizontal
Scale
Factor
Y/RGB
Integer
Integer
X Scale Factor Y/RGB
Re
ser
ved
Vertical
Down
Scale
Scale
Integer
Bit Description
31:20
Vertical Scale Factor Y/RGB. This is a fractional positive number that represents the scale factor to
be used in vertical scaling. For packed formats, it applies to all color components and for planar YUV
formats it is use for the Y component only. Always Bit 31:20 1 > scale
be used in vertical scaling. For packed formats, it applies to all color components and for planar YUV
formats it is use for the Y component only. Always Bit 31:20 1 > scale
≥ 1/64 (the maximum vertical up
zoom is 64X) (1/Scale for up scale fractional portion of the scale factor for down scaling)
19:17
Reserved.
16:15
Horizontal Scale Factor Y/RGB Integer. This field is used only for horizontal down scale. In the case
of planar formats, it specifies the integer portion of the scale factor for Y data. Only Horizontal down
scaling of 2 (or less) to 1 is supported.
of planar formats, it specifies the integer portion of the scale factor for Y data. Only Horizontal down
scaling of 2 (or less) to 1 is supported.
14:3
Horizontal Scale Factor Y/RGB. This is a fractional positive number that represents the scale factor
to be used in horizontal scaling. Always 1>scale
to be used in horizontal scaling. Always 1>scale
≥0
2
Reserved.
1:0
Vertical Down Scale Integer. This field is used only for vertical down scale. In the case of planar
formats, it specifies the integer portion of the scale factor for Y data.
formats, it specifies the integer portion of the scale factor for Y data.