Datasheet

11
SLES084C − August 2007 TVP5146
Copy
Protection
Detector
VBI Data
Processor
Output
Formatter
Composite
Processor
CVBS/Y
C
YCbCr
Y[9:0]
Timing
Processor
AVID
FID
GLCO
XTAL1
XTAL2
RESETB
Component
Processor
CH1 A/D
CH2 A/D
CH3 A/D
Pr/R
Pb/B
Y/G
YCbCr
FSS
HS/CS
VS/VBLK
DATACLK
C[9:0]
CH4 A/D
CVBS/Y/G
Host
Interface
SCL
SDA
Slice VBI Data
2
Decimation
PWDN
2
Decimation
2
Decimation
2
Decimation
Figure 2−2. Digital Video Processor Block Diagram
2.2.1 2y Decimation Filter
All input signals are oversampled by a factor of 2 (27 MHz). The A/D outputs first pass through
decimation filters that reduce the data rate to 1× the pixel rate. The decimation filter is a
half-band filter. Oversampling and decimation filtering can effectively increase the overall
signal-to-noise ratio by 3 dB.
2.2.2 Composite Processor
Figure 2−3 is a block diagram of the TVP5146 digital composite video processing circuit. This
circuit receives a digitized composite or S-video signal from the ADCs and performs Y/C
separation (bypassed for S-video input), chroma demodulation for PAL/NTSC and SECAM, and
YUV signal enhancements.
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.