AK8850 Datasheet, PDF (57/99 Pages) Asahi Kasei Microsystems – NTSC Digital Video Decoder

ASAHI KASEI
[AK8850]
7-4-11 CLOSED CAPTION/CLOSED CAPTION EXTENDED DATA/VBID ( CGMS )/WSS
It is possible to request decoding of Closed Caption, Closed Caption Extended Data, VBID and WSS signals by
programming the [ REQUEST VBI INFORMATION REGISTER ].
The [ STATUS 2 REGISTER ] tells a host that data is detected and idecoding has been completed for a given decode
request.
Decoded data are written into the [ CLOSED CAPTION 1.2 REGISTER ], [ VBID 1.2 REGISTER ], [ WSS 1 REGISTER ]
and [ WSS 2 & ASPECT DATA REGISTER ] respectively.
The Closed Caption Data, Closed Caption Extended Data, VBID and WSS Data are encoded on each specified line
respectively as listed below.
Closed Caption
: NTSC specified line 21^st Line
Closed Caption Extended Data : NTSC specified line 284^th Line
VBID ( CGMS Data ) : 525 system specified line 20^th Line / 238^th Line
625 system specified line 20^th Line / 338^th Line
WSS ( 625 system only ) : 625 system specified line 23^rd Line
VBI Information Request Register :
* [ REQUEST VBI INFO REGISTER ]
bit 7
bit 6
bit 5
Reserved Reserved Reserved
0
0
* [ STATUS 2 REGISTER ]
bit 7
bit 6
APS1
APS0
0
bit 5
Reserved
bit 4
bit 3
WSSRQ VBIDRQ
Default Value
0
0
bit 4
WSS
bit 3
VBID
bit 2
EXTRQ
0
bit 2
EXT
* Read –out Line Number of the VBI information for each mode is as follows.
NTSC(525 System)
Composite Y/C
Component
Betacam
MII
Closed Caption
Line 21
Extended Data
Line 284
VBID
Line 20/Line 283
WSS
bit 1
CCRQ
0
bit 0
ASPECTRQ
0
bit 1
bit 0
CC
ASPECT
625 System
Component
Line 22
Line 335
Line 20/Line 333
Line 23
Rev.0
57
2003/01