Datasheet

Functional Description
12
SLES099C—March 2007TVP5147PFP
The 10-bit composite video is multiplied by the subcarrier signals in the quadrature demodulator to generate
color difference signals U and V. The U and V signals are then sent to low-pass filters to achieve the desired
bandwidth. An adaptive 5-line comb filter separates UV from Y based on the unique property of color phase
shifts from line to line. The chroma is remodulated through a quadrature modulator and subtracted from
line-delayed composite video to generate luma. This form of Y/C separation is completely complementary,
thus there is no loss of information. However, in some applications, it is desirable to limit the U/V bandwidth
to avoid crosstalk. In that case, notch filters can be turned on. To accommodate some viewing preferences,
a peaking filter is also available in the luma path. Contrast, brightness, sharpness, hue, and saturation controls
are programmable through the host port.
Line
Delay
–
Peaking
NTSC/PAL
Remodulation
NTSC/PAL
Demodulation
Notch
Filter
Color LPF
↓ 2
5-Line
Adaptive
Comb
Filter
Notch
Filter
Notch
Filter
Notch
Filter
Contrast
Brightness
Saturation
Adjust
Cr
Y
Cb
Y
Burst
Accumulator
(U)
U
SECAM
Color
Demodulation
V
Delay
CVBS/Y
SECAM Luma
CVBS
CVBS/C
Color LPF
↓ 2
Burst
Accumulator
(V)
U
V
Delay
Delay
Figure 2−3. Composite and S-Video Processing Block Diagram
2.2.2.1 Color Low-Pass Filter
High filter bandwidth preserves sharp color transitions and produces crisp color boundaries. However, for
nonstandard video sources that have asymmetrical U and V side bands, it is desirable to limit the filter
bandwidth to avoid UV crosstalk. The color low-pass filter bandwidth is programmable to enable one of the
three notch filters. Figure 2−4 through Figure 2−7 represent the frequency responses of the wideband color
low-pass filters.