BT860-BT861 Datasheet, PDF (43/111 Pages) Conexant Systems, Inc – Multiport YCrCb to NTSC / PAL / SECAM Digital Video Encoder

Bt860/861
Multiport YCrCb to NTSC/PAL /SECAM
3.0 Digital Processing and Functionality
3.2 Effects
3.2 Effects
3.2.1 Chrominance Disable
Setting register bit DCHROMA (17[2]) to 1 turns off the chrominance subcarrier
and colorburst.
3.2.2 Internal Filtering
Once the input data is converted to internal YUV format, the Y and UV
components are filtered and upsampled to the system clock frequency.
The luminance signal is always low-pass filtered using the upsampling filter
response illustrated in Figure 3-3. Additional peaking or reduction filters can be
enabled (see Figures 3-4 and 3-5), using the PKFIL_SEL register field and the
FIL_SEL register bit. When register bit FIL_SEL is set to 0, register field
PKFIL_SEL selects the peaking filters illustrated in Figure 3-7. When register bit
FIL_SEL is set to 1, register field PKFIL_SEL selects the reduction filters
illustrated in Figure 3-6. The peaking filters are optimized for high bandwidth
frequency response, and the reduction filters are optimized for step response
performance.
The default chrominance filter response is illustrated in Figure 3-8, but an
alternate wide bandwidth response can be selected using register bit
CHROMA_BW, as illustrated in Figure 3-9.
SECAM pre-emphasis filter responses are illustrated in Figures 3-10 and 3-11.
.
Figure 3-3. Luminance Upsampling Filter
Figure 3-4. Luminance Upsampling Filter with Peaking
and Reduction Options
0
–10
–20
–30
–40
–50
–60
–70
–80
0
2
4
6
8
10
12
Frequency in MHz
861_015
0
–10
–20
–30
–40
–50
–60
0
2
4
6
8
10
12
Frequency in MHz
861_016
D860DSA
Conexant
3-13