2004 Jun 29
189
Philips Semiconductors
Product specification
HD-CODEC
SAA7108AE; SAA7109AE
19.4
Scaler and interfaces
Table 246 shows some examples for the scaler
programming where:
prsc = prescale ratio
fisc = fine scale ratio
vsc = vertical scale ratio.
The ratio is defined as:
In the following settings the VBI data slicer is inactive.
To activate the VBI data slicer, VITX[1:0] 86H[7:6] has to
be set to ‘11’. Depending on the VBI data slicer settings,
the sliced VBI data is inserted after the end of the scaled
video lines, if the regions of the VBI data slicer and scaler
overlap.
To compensate for the running-in of the vertical scaler, the
vertical input window lengths are extended by
2 to 290 lines, respectively 242 lines for XS, but the scaler
increment calculations are done with 288, respectively
240 lines.
19.4.1
T
RIGGER CONDITION
For trigger condition STRC[1:0] 90H[1:0] not equal ‘00’.
If the value of (YO + YS) is
≥
262 (NTSC), and 312 (PAL)
the output field rate is reduced to 30 Hz and 25 Hz
respectively.
Horizontal and vertical offsets (XO and YO) have to be
used to adjust the displayed video in the display window.
As this adjustment is application dependent, the listed
values are only dummy values.
19.4.2
M
AXIMUM ZOOM FACTOR
The maximum zoom factor is dependent on the back-end
data rate and is therefore back-end clock and data format
dependent (8 or 16-bit output). The maximum horizontal
zoom is limited to approximately 3.5, due to internal data
path restrictions.
number of output pixel
--number of input pixel
19.4.3
E
XAMPLES
Table 246
Example of configurations
EXAMPLE
NUMBER
SCALER SOURCE AND REFERENCE EVENTS
INPUT
WINDOW
720
×
240 720
×
240 prsc = 1;
OUTPUT
WINDOW
SCALE
RATIOS
1
analog input to 8-bit I port output, with SAV/EAV codes, 8-bit
serial byte stream decoder output at X port; acquisition trigger
at falling edge vertical and rising edge horizontal reference
signal; H and V gates on IGPH and IGPV, IGP0 = VBI sliced
data flag, IGP1 = FIFO almost full, level
≥
24, IDQ qualifier
logic 1 active
analog input to 16-bit output, without SAV/EAV codes, Yon
I port, C
B
-C
R
on H port and decoder output at X port;
acquisition trigger at falling edge vertical and rising edge
horizontal reference signal; H and V pulses on IGPH and IGPV,
output FID on IGP0, IGP1 fixed to logic 1, IDQ qualifier logic 0
active
X port input 8 bit with SAV/EAV codes, no reference signals on
XRH and XRV, XCLK as gated clock; field detection and
acquisition trigger on different events; acquisition triggers at
rising edge vertical and rising edge horizontal; I port output
8-bit with SAV/EAV codes like example number 1;
see Table 247
X port and H port for 16-bit Y-C
B
-C
R
4 : 2 : 2 input (if no 16-bit
output selected); XRH and XRV as references; field detection
and acquisition trigger at falling edge of vertical and rising edge
of horizontal; I port output 8-bit with SAV/EAV codes, but Yonly
output
fisc = 1;
vsc = 1
2
704
×
288 768
×
288 prsc = 1;
fisc = 0.91667;
vsc = 1
3
720
×
240 352
×
288 prsc = 2;
fisc = 1.022;
vsc = 0.8333
4
720
×
288 200
×
80
prsc = 2;
fisc = 1.8;
vsc = 3.6