Intel 815 manual Overlay Source Color Key Registers, SCLRKVH-Source Color Key Value High Register

Models: 815

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Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

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15.4.9.Overlay Source Color Key Registers

There is an overlay source key per overlay stream, which is used on a pixel basis. The Source comparison occurs after the horizontal zooming, but in the YUV formats before the color space conversion. If the source data (overlay) is within the range, then the primary display is selected.

If the overlay is in RGB mode, the most significant bits are duplicated on the least significant to form 8 bit channels:

R<4:0> -> R<4:0 ‘ 4:2>

G<5:0> -> G<5:0 ‘ 5:4>

B<4:0> -> B<4:0 ‘ 4:2>

before the source key comparison is made.

Destination Color Key failing takes precedence over the Source Chroma Key failing. If both fail, then the primary display is selected.

15.4.9.1.SCLRKVH—Source Color Key Value High Register

Memory Address Offset:

 

58h (R/W)

On-chip Reg. Mem Addr Offset:

30158h (RO; debug path)

Default Value:

 

00h

Access:

 

 

see address offset above

Size:

 

 

32 bits

31

24

23

0

 

 

 

 

Reserved

 

Source Key value High

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

 

Description

 

 

 

 

 

 

 

31:24

Reserved.

 

 

 

 

 

 

 

23:0

Source Key Value High. This value is the high value that is compared with the overlay pixel per 8 bit

 

 

 

channel. An overlay value greater than this field on any channel that is enabled fails the comparison

 

 

 

and passes the overlay pixel.

 

 

 

 

 

 

 

 

 

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Page 290
Image 290
Intel 815 manual Overlay Source Color Key Registers, SCLRKVH-Source Color Key Value High Register