
ADV7194
–17–
REV. A
FEATURES—FUNCTIONAL DESCRIPTION
BLACK BURST OUTPUT
It is possible to output a black burst signal from two DACs. This
signal output is very useful for professional video equipment
since it enables two video sources to be locked together. (Mode
Register 9.)
BLACK BURST OUTPUT
CVBS
DIGITAL DATA
GENERATOR
ADV7194
DIGITAL DATA
GENERATOR
ADV7194
Figure 27. Possible Application for the Black Burst Output
Signal
BRIGHTNESS DETECT
This feature is used to monitor the average brightness of the
incoming Y video signal on a eld by eld basis. The informa-
tion is read from the I
2C and based on this information the color
saturation, contrast and brightness controls can be adjusted
(for example to compensate for very dark pictures). (Bright-
ness Detect Register.)
CHROMA/LUMA DELAY
The luminance data can be delayed by maximum of six clock
cycles. Additionally the Chroma can be delayed by a maximum
of eight clock cycles (one clock cycle at 27 MHz). (Timing Reg-
ister 0 and Mode Register 9.)
CHROMA DELAY
LUMA DELAY
Figure 28. Chroma Delay
Figure 29. Luma Delay
CLAMP OUTPUT
The ADV7194 has a programmable clamp TTL output signal.
This clamp signal is programmable to the front and back porch.
The clamp signal can be varied by one to three clock cycles in
a positive and negative direction from the default position. (Mode
Register 5, Mode Register 7.)
CVBS
OUTPUT PIN
CLAMP
OUTPUT PIN
MR57 = 1
MR57 = 0
CLAMP O/P SIGNALS
Figure 30. Clamp Output Timing
CSO, HSO, AND VSO OUTPUTS
The ADV7194 supports three output timing signals,
CSO (com-
posite sync signal),
HSO (Horizontal Sync Signal) and VSO
(Vertical Sync Signal). These output TTL signals are aligned
with the analog video outputs. See Figure 31 for an example
of these waveforms. (Mode Register 7.)
OUTPUT
VIDEO
525
1
23456789
10
11–19
EXAMPLE:- NTSC
CSO
HSO
VSO
Figure 31.
CSO, HSO, VSO Timing Diagram
COLOR BAR GENERATION
The ADV7194 can be congured to generate 100/7.5/75/7.5
color bars for NTSC or 100/0/75/0 color bars for PAL. (Mode
Register 4.)
COLOR BURST SIGNAL CONTROL
The burst information can be switched on and off the composite
and chroma video output. (Mode Register 4.)
COLOR CONTROLS
The ADV7194 allows the user to control the brightness, contrast,
hue and saturation of the color. The control registers may be
double-buffered, meaning that any modication to the registers
will be done outside the active video region and, therefore, changes
made will not be visible during active video.
Contrast Control
Contrast adjustment is achieved by scaling the Y input data by a
factor programmed by the user. This factor allows the data to be
scaled between 0% and 150%. (Contrast Control Register.)
Brightness Control
The brightness is controlled by adding a programmable setup level
onto the scaled Y data. This brightness level may be added onto
the Y data. For NTSC with pedestal, the setup can vary from
0 IRE to 22.5 IRE. For NTSC without pedestal and PAL, the
setup can vary from –7.5 IRE to +15 IRE. (Brightness Control
Register.)
Color Saturation
Color adjustment is achieved by scaling the Cr and Cb input
data by a factor programmed by the user. This factor allows the
data to be scaled between 0% and 200%. (U Scale Register and
V Scale Register.)
Hue Adjust Control
The hue adjustment is achieved on the composite and chroma
outputs by adding a phase offset onto the color subcarrier in the
active video but leaving the color burst unmodied, i.e., only
the phase between the video and the colorburst is modied and
hence the hue is shifted. The ADV7194 provides a range of
± 22° in increments of 0.17578125°. (Hue Adjust Register.)
CHROMINANCE CONTROL
The color information can be switched on and off the com-
posite, chroma and color component video outputs. (Mode
Register 4.)