AK8817_09 Datasheet, PDF (34/50 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Encoder

ASAHI KASEI
[AK8817/18]
( 17 ) WSS function
The AK8817/18 supports to encode the WSS ( ITU-R. BT.1119 ) which distinguishes the aspect ratio and sets CGMS-A
etc..
Turning “ON/OFF“ of this function is made by setting both VMOD-bit = 1 and WSS-bit = 1 of { Control 1 Register ( 0x00 ) }.
And data to be set is written into { VBID / WSS Data1 & 2 Registers ( 0x02, 0x03 )}.
WSS Data Update timing
VSYNC
u-P Data
Set C ontrol R egister
NEW DATA
DATA
OLD DATA
NEW DATA
WSS Waveform
500mV +/- 5%
0H
1.5usec
10.5usec
11.0 +/- 0.25usec
27.4usec
38.4usec
44.5usec
Encode line : former half of Line 23 ( Blank output during latter half )
Coding : Bi-phase modulation coding
Clock : 5 MHz ( Ts = 200 nS )
Encoding details as follows
Run-in
Start code
29 elements
24 elements
0x1F1C71C7
0x1E3C1F
Group 1
Aspect ratio
24 elements
Bit numbering
0123
LSB
MSB
0 : 000111
1 : 111000
Group 2
Enhanced
Services
24 elements
Bit numbering
4567
LSB
MSB
0 : 000111
1 : 111000
Group 3
Subtitles
18 elements
Bit numbering
8 9 10
LSB MSB
0 : 000111
1 : 111000
Group4 Reserved
18 elements
Bit numbering
11 12 13
LSB MSB
0 : 000111
1 : 111000
Rev.001E
34
2009 / 12