SAA7108AE 데이터 시트보기 (PDF) - Philips Electronics
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SAA7108AE Datasheet PDF : 197 Pages
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Philips Semiconductors
HD-CODEC
Product specification
SAA7108AE; SAA7109AE
Table 3 Layout of a byte in the cursor bit map
D7 D6
pixel n + 3
D1 D0
D5 D4
pixel n + 2
D1 D0
D3 D2
pixel n + 1
D1 D0
D1 D0
pixel n
D1 D0
For each direction, there are 2 registers controlling the
position of the cursor, one controls the position of the
‘hot spot’, the other register controls the insertion position.
The hot spot is the ‘tip’ of the pointer arrow. It can have any
position in the bit map. The actual position registers
describe the co-ordinates of the hot spot. Again 0,0 is the
upper left corner. While it is not possible to move the
hot spot beyond the left respectively upper screen border
this is perfectly legal for the right respectively lower border.
It should be noted that the cursor position is described
relative to the input resolution.
Table 4 Cursor bit map
BYTE D7 D6 D5 D4 D3 D2 D1 D0
0
row 0
row 0
row 0
row 0
column 3 column 2 column 1 column 0
1
row 0
row 0
row 0
row 0
column 7 column 6 column 5 column 4
2
row 0
row 0
row 0
row 0
column 11 column 10 column 9 column 8
...
...
...
...
...
6
row 0
row 0
row 0
row 0
column 27 column 26 column 25 column 24
7
row 0
row 0
row 0
row 0
column 31 column 30 column 29 column 28
...
...
...
...
...
254 row 31 row 31 row 31 row 31
column 27 column 26 column 25 column 24
255 row 31 row 31 row 31 row 31
column 31 column 30 column 29 column 28
Table 5 Cursor modes
CURSOR
PATTERN
CURSOR MODE
CMODE = 0
CMODE = 1
00
second cursor colour second cursor colour
01
first cursor colour first cursor colour
10
transparent
transparent
11
inverted input
auxiliary cursor
colour
8.5 RGB Y-CB-CR matrix
RGB input signals to be encoded to PAL or NTSC are
converted to the Y-CB-CR colour space in this block. The
colour difference signals are fed through low-pass filters
and formatted to a ITU-R BT.601 like 4 : 2 : 2 data stream
for further processing.
A gain adjust option corrects the level swing of the
graphics world (black-to-white as 0 to 255) to the required
range of 16 to 235.
The matrix and formatting blocks can be bypassed for
Y-CB-CR graphics input.
When the auxiliary VGA mode is selected, the output of the
cursor insertion block is immediately directed to the triple
DAC.
8.6 Horizontal scaler
The high quality horizontal scaler operates on the 4 : 2 : 2
data stream. Its control engines compensate the colour
phase offset automatically.
The scaler starts processing after a programmable
horizontal offset and continues with a number of input
pixels. Each input pixel is a programmable fraction of the
current output pixel (XINC/4096). A special case is
XINC = 0, this sets the scaling factor to 1.
If the SAA7108AE; SAA7109AE input data is in
accordance with “ITU-R BT.656”, the scaler enters
another mode. In this event, XINC needs to be set to 2048
for a scaling factor of 1. With higher values, upscaling will
occur.
The phase resolution of the circuit is 12 bits, giving a
maximum offset of 0.2 after 800 input pixels. Small FIFOs
rearrange a 4 : 2 : 2 data stream at the scaler output.
2004 Jun 29
20
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