2001 Sep 25
12
Philips Semiconductors
Product specification
Digital video encoder
SAA7102; SAA7103
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.
WhentheauxiliaryVGAmodeisselected,theoutputofthe
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.
Thecircuitgeneratestheinterlacedoutputfieldsbyscaling
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 94.
Theprogrammingissimilartothehorizontalscaler.Forthe
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 7
row 0
column
11
...
row 0
column
27
row 0
column
31
...
row 31
column
27
row 31
column
31
row 0
column 2
row 0
column 6
row 0
column
10
...
row 0
column
26
row 0
column
30
...
row 31
column
26
row 31
column
30
row 0
column 1
row 0
column 5
row 0
column 9
row 0
column 0
row 0
column 4
row 0
column 8
1
2
...
6
...
...
row 0
column
25
row 0
column
29
row 0
column
24
row 0
column
28
7
...
254
...
...
row 31
column
25
row 31
column
29
row 31
column
24
row 31
column
28
255
CURSOR
PATTERN
CURSOR MODE
CMODE = 0
CMODE = 1
00
01
10
11
second cursor colour second cursor colour
first cursor colour
transparent
inverted input
first cursor colour
transparent
auxiliary cursor
colour