msm7664 Oki Semiconductor, msm7664 Datasheet - Page 18

• Manufacturer Part Number: msm7664
• Description: Ntsc/pal Digital Video Decoder
• Manufacturer: Oki Semiconductor

¡ Semiconductor
Decoder Unit
1. Prologue Block
The prologue block inputs data and performs Y/C separation.
Data can be input at either the pixel frequency (ITU-RBT.601: 13.5 MHz) or at twice the pixel
frequency (ITU-RBT.601: 27 MHz). If input at twice the pixel frequency, data is processed after
passing through a decimator circuit to convert it to the pixel frequency. The decimator circuit
may be bypassed by changing the register setting, regardless of whether data is input at the
normal pixel frequency or at twice the pixel frequency.
If a composite signal (CVBS) is input, the default setting performs Y/C separation using a 2-
dimensional adaptive comb filter.
The following operating modes can be selected via the I
an asterisk (*). The default state is selected at reset.
1) Video input mode selection (related register MRC[7])
2) Operating mode selection (related register MRA[3:1])
3) Decimator circuit pass/bypass selection (related register MRC[4])
4) Y/C separation mode selection (related register MRB[1:0])
The adaptive comb filter for a NTSC signal makes the correlation between up to 3 consecutive
lines, and Y/C separation is performed by the 3-line or 2-line comb filter according to the format
of correlation.
The adaptive comb filter for a PAL signal makes the correlation between only 2 lines and
performs Y/C separation by switching between the 2-line comb filter and trap filter.
At that time, the adaptive transition method is employed in which the filter is gradually switched
depending on the level of correlation.
The non-adaptive comb filter performs Y/C separation by removing the luminance component
based on the average of preceding and following lines (when there is correlation between 3 lines).
(the average of 2 lines in the case of a PAL signal)
When a comb filter is not used, Y/C separation is performed by a trap filter.
Even if input at twice the pixel frequency, the internal processing is performed at the pixel
frequency.
Compatible only when input at twice the pixel frequency.
NTSC/PAL auto-select* (only for ITU-RBT.601)
Dependent upon operating mode selected
When ITU-RBT.601 is selected, the video input mode is automatically set depending upon
the number of lines per field.
NTSC ITU-RBT.601
NTSC Square Pixel
NTSC 4fsc
PAL ITU-RBT.601
PAL Square Pixel
Pass through decimator circuit*
Bypass decimator circuit
Use adaptive comb filter*
Use non-adaptive comb filter
Do not use comb filter (use trap filter)
13.5 MHz*
12.272727 MHz
14.31818 MHz
13.5 MHz
14.75 MHz
2
C-bus. Default settings are indicated by
PEDL7664-01
MSM7664
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