Rastergraf Topaz, User Manual

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Rastergraf
1-16 General Information
1.4 Bt835 NTSC/PAL/SECAM Digitizer
The Topaz/Stratus/Garnet provides a Conexant Bt835 video-capture
processor, a single-chip decoding and filtered scaling solution for VCRs,
cameras, and other sources of composite or component (S-Video or Y/C)
video. It integrates video digitization, auto NTSC/PAL format detect and
gain control, synchronization, 2H adaptive Y/C separation (comb filter),
horizontal and vertical filtered down-scaling, user programmable peaking
filter, and VBI data pass-through functions. An internal loopback can be
enabled by software to connect the Composite Video Output to a
Composite Video Input for testing
Using mixed signal and DSP circuitry, the Bt835 converts square pixel
and CCIR601 resolution analog S-Video, NTSC, PAL, and SECAM base-
band signals composite video into a scaled to YCrCb digital video stream
An input multiplexer allows the user to select between four composite
input channels or an S-Video input. Hue, saturation, brightness and
contrast controls provide added flexibility to enhance the appearance of
the decoded image. Cropping and scaling can shrink the input image to no
more than is needed for display. This reduces the bandwidth requirement
of the capture and playback engines, leaving more time for graphics
drawing and display refresh. A minimum scale factor of 0.071 allows a
full-resolution video image to be reduced to icon size.
Figure 1-11 Bt835 Video Digitizer Block Diagram
MUX0
MUX1
CLKx1
CLKx2
RST
SDA
I2CCS
SCL
QCLK
HRESET
VRESET
ACTIVE
FIELD
CBFLAG
VALID
Video Sc
aling
Input Interf
ace
Output Int
erf
ace
Y/C Se
parat
ion
an
d
Chrom
a De
mo
du
lati
on
Video
I 2
C Interf
ace
OE
VD[15:8]
VD[7:0]
A
G
CCAP
RE
FOU
T
CIN
Cloc
k Interf
ac
e
JT
A
G
Interf
ace
an
d Cro
ppi
ng
Adju
st
men
ts
C
A/D
Y
A/D
Oversampling
Low-Pass Filter
Y/C
Separation
Chroma
Demod
Contrast, Saturation,
and Brightness
Adjust
Horizontal and
Vertical Filtering
and Scaling
Digital Video
Vide
o Tim
ing
Con
trol
I
2
C
Cloc
king
JTAG
TD
O
TDI
TM
S
TCK
TRST
MUX2
CCVALID
VACTIVE
AGC and
MUX3
Sync Detect
Output Formatting
PWRDN
LV
T
T
L
GPIO P
o
rt GPIO[7:0]
Digita
l Vi
deo
Inpu
t F
o
rm
atti
ng
DIG_CLK
VD[7:0]
DIG_V
DIG_H