AK8851 Datasheet, PDF (42/80 Pages) Asahi Kasei Microsystems – NTSC/PAL/SECAM Digital Video Decoder

ASAHI KASEI
[AK8851]
25. Decode Data Output ( Rec.601 limit / YC Delay / Timing )
The AK8851 outputs decoded data in ITU-R BT.601 compatible format (Y /Cb /Cr 4:2:2). The minimum and maximum
output code values are selectable by the [601 LIMIT]-bit of [Output Format Register](R/W)[Sub Address 0x02].
The AK8851 also allows ine-tuning of the decoded data’s output timing ..
Adjustable parameters are the Active Video Interval Start Position and Delay Time for Luminance and Chroma signals. YC
Delay time and Active Video Interval Start Position are programmable via the [Start and Delay Control Register].
Bit allocation of [Output Format Register] is shown below.
Sub Address 0x02
bit 7
bit 6
VBIDEC1
VBIDEC0
0
0
bit 5
SLLVL
0
bit 4
bit 3
TRSVSEL 601LIMIT
Default Value
0
0
bit 2
VBIL2
0
Default Value : 0x00
bit 1
bit 0
VBIL1
VBIL0
0
0
[601 LIMIT]-bit :
This bit specifies Min. and Max. values of output data. Internal arithmetic operation is performed, based on Min.=1 and
Max.=254 always.
The output code Clipping value also differs by [601 LIMIT]-bit setting. Default value is “0”.
[601LIMIT]-bit
0
1
Output code Min/Max
Y: 1~254
Cb/Cr: 1~254
Y: 16~235
Cb/Cr: 16~240
Note
Default
Bit allocation of [Start and Delay Control Register] is listed below.
Sub Address 0x05
bit 7
bit 6
Reserved ACTSTAT2
0
0
bit 5
ACTSTAT1
0
bit 4
bit 3
ACTSTAT0 Reserved
Default Value
0
0
bit 2
YCDELAY2
Default Value : 0x00
bit 1
bit 0
YCDELAY1 YCDELAY0
0
0
0
[YCDELAY2 : YCDELAY0]-bit :
This control bit to fine-tunes the YC output timing (YC Output Delay) for the decoded data.
* Fine-tuning of YC Output Delay Time is set in 2’s complement number.
[YCDELAY2:YCDELAY0]-bit
YC Delay
101
Y data is delayed 3 samples (222nsec) to C data
110
Y data is delayed 2 samples (148nsec) to C data
111
Y data is delayed 1 sample (74nsec) to C data
000
No delay between Y data and C data
001
Y data is advanced 1 sample (72nsec) to C data.
010
Y data is advanced 2 samples (148nsec) to C data.
011
Y data is advanced 3 samples (222nsec) to C data.
Note
Default
MS0244-E-03
42
Confidential
2005 / 07