AK8858 Datasheet, PDF (33/96 Pages) Asahi Kasei Microsystems – PS/SD Multi Format Video Decoder

[AK8858]
[7.11] Slice function
The results of VBI slicing by the AK8858 slicing function are output as ITU-R BT.601 digital data. The VBI
interval is set via VBIL[2:0]-bits. VBI slicing is performed in the luminance in the luminance signal processing
path, so that the Cb/Cr value of the effective line 601 output code is output at the same level as the
corresponding luminance signal.
Setting for slice level
Name
Definition
SLLVL
[0]: 25IRE
[1]: 50IRE
Sub Address: 0x05 [5]
Hi/Low Slice Data Set Register of output data, as follows.
Setting for higher of two values resulting from slicing
Name
Definition
H0
~
H7
Default: 0xEB(235)
Note that a setting of 0x00 or 0xFF corresponds to a special 601 code.
Sub Address: 0x18
Setting for lower of two values resulting from slicing
Name
Definition
L0
~
L7
Default: 0x10(16)
Note that a setting of 0x00 or 0xFF corresponds to a special 601 code.
* (mV)
NTSC/PAL
601 Code
714/700 235
100% White
Sub Address: 0x19
357/350 127
180/175 ⁶³
50IRE threshold with setting
SLLVL=[1]
25IRE threshold with setting
SLLVL=[0]
L L _{````</sub> L L H H <sub>````} H H
`````
Cb/Y <sub>``````</sub> Cr/Y
Cb/Y <sub>``````</sub> Cr/Y
*Threshold values (mV) are approximate
L:
Value set by
Set Register
Low
Slice
Data
H:
Value set by
Set Register
High
Slice
Data
L
```````
High/Low conversion is performed for either the Cb/Y or the Cr/Y combination. The above figure is an example
of the conversion points for Cb/Y.
MS1230-E-00
- 33 -
2010/9