cx25870 Conexant Systems, Inc., cx25870 Datasheet - Page 45

• Manufacturer Part Number: cx25870
• Description: Video Encoder With Adaptive Flicker Filtering And Hdtv Output
• Manufacturer: Conexant Systems, Inc.

CX25870/871
Flicker-Free Video Encoder with Ultrascale Technology
Figure 1-8. Decimation Filter at Fs=27 MHz
100381B
10
15
20
25
30
35
40
45
0
5
0
1
4:4:4 data is input, it is subsampled to 4:2:2 prior to overscan compensation and
flicker filtering.
scaled for the output range of the DACs. The MY, MCR, and MCB registers must
be programmed to perform this conversion. The scaling equations are as follows:
MY = (int) [V100/(219.0
MCR = (int)[(128.0/127.0)
MCB = (int)[(128.0/127.0)
where:V
V
F
F
Sinx = Sin ($#·F
sc
FS
clk
Figure 1-8
The resulting 4:2:2 output must then be converted to YUV values and then
= color subcarrier frequency (see
= Full scale output voltage (1.28 V)
= Analog pixel rate
100
2
= 100% white voltage (0.661 V for NTSC, 0.7 V for PAL/SECAM)
illustrates the frequency response of the sub-sampling process. If
SC
Chroma Decimation Filter
Frequency (Fs = 27 MHz)
/F
Conexant
CLK
3
)/($#·F
*
V
*
*
FS
V
V
100 *
)
100 *
SC
*
2
/F
6
0.493/(224.0
0.877/(224.0
CLK
+ 0.5]
4
Table
)
A-2)
*
*
V
V
5
FS *
FS *
0.564
0.713
1.0 Functional Description
*
1.3 Device Description
*
sinx)
sinx)
6
*
*
2
2
6
6
+ 0.5]
+ 0.5]
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