2004 Mar 01
12
Philips Semiconductors
Product specification
Digital video encoder
SAA7102; SAA7103
It can have any position in the bit map. The actual position
register 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
Table 5
Cursor modes
7.5
RGB Y-C
B
-C
R
matrix
RGB input signals to be encoded to PAL or NTSC are
converted to the Y-C
B
-C
R
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.
The matrix and formatting blocks can be bypassed for
Y-C
B
-C
R
graphics input.
When the auxiliary VGA mode is selected, the output of the
cursor insertion block is immediately directed to the triple
DAC.
7.6
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 SAA7102; SAA7103 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.
7.7
Vertical scaler and anti-flicker filter
The functions scaling, Anti-Flicker Filter (AFF) and
re-interlacing are implemented in the vertical scaler.
Besides the entire input frame, it receives the first and last
lines of the border to allow anti-flicker filtering.
The circuit generates the interlaced output fields by scaling
down the input frames with different offsets for odd and
even fields. Increasing the YSKIP setting reduces the
anti-flicker function. A YSKIP value of 4095 switches it off;
see Table 95.
The programming is similar to the horizontal scaler. For the
re-interlacing, the resolutions of the offset registers are not
sufficient, so the weighting factors for the first lines can
also be adjusted. YINC = 0 sets the scaling factor to 1;
YIWGTO and YIWGTE must not be 0.
Due to the re-interlacing, the circuit can perform upscaling.
The maximum factor depends on the setting of the
anti-flicker function and can be derived from the formulae
given in Section 7.17.
BYTE
D7
D6
D5
D4
D3
D2
D1
D0
0
row 0
column 3
row 0
column 2
row 0
column 1
row 0
column 0
1
row 0
column 7
row 0
column 6
row 0
column 5
row 0
column 4
2
row 0
column
11
row 0
column
10
row 0
column 9
row 0
column 8
...
...
...
...
...
6
row 0
column
27
row 0
column
26
row 0
column
25
row 0
column
24
7
row 0
column
31
row 0
column
30
row 0
column
29
row 0
column
28
...
...
...
...
...
254
row 31
column
27
row 31
column
26
row 31
column
25
row 31
column
24
255
row 31
column
31
row 31
column
30
row 31
column
29
row 31
column
28
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