AMD Geode LX 800@0.9W - Manual (Page 427)

AMD Geode™ LX Processors Data Book 427
Video Processor Register Descriptions 33234H
6.8.3.7 Video Color Mask (VCM)
23:0 VID_CLR_KEY Video Color Key. The video color key is a 24-bit RGB or YUV value.
• If VG_CK (VP Memory Offset 008h[20]) is set to 0, the video pixel is selected within
the target window if the corresponding graphics pixel matches the color key. The color
key is an RGB value.
• If VG_CK (VP Memory Offset 008h[20]) is set to 1, the video pixel is selected within
the target window only if it (the video pixel) does not match the color key. The color key
is usually an RGB value. However, if both GV_SEL and CSC_VIDEO (VP Memory
Offset 098[13,10] are set to 0, the color key is a YUV value (i.e., video is not converted
to RGB).
The graphics or video data being compared can be masked prior to the compare via the
Video Color Mask register (VP Memory Offset 030h). The video color key can be used to
allow irregular shaped overlays of graphics onto video, or video onto graphics, within a
scaled video window.
VP Memory Offset 030h
Type
R/W
Reset Value 00000000_00000000h
VCK Bit Descriptions (Continued)
Bit Name Description
VCM Register Map
63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
RSVD
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RSVD VID_CLR_MASK
VCM Bit Descriptions
Bit Name Description
63:24 RSVD (RO) Reserved (Read Only). Reads back as 0.
23:0 VID_CLR_
MASK Video Color Mask. This mask is a 24-bit RGB value. Zeros in the mask cause the corre-
sponding bits in the graphics or video stream to be forced to match.
For example:
A mask of FFFFFFh causes all 24 bits to be compared (single color match).
A mask of 000000h causes none of the 24 bits to be compared (all colors match).
For more information about the color key, see VP Memory Offset 028h on page 426. The
video color mask is used to mask bits of the graphics or video stream being compared to
the color key. It allows a range of values to be used as the color key.