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3.2.3 BT.656 Image Window and Capture
Capture Image
Ystart
Xstart
Ystop
Xstop
Field 1
Capture Image
Ystart
Xstart
Ystop
Xstop
Field 2
Hcount=0
Ycount=1
Ycount=1
BT.656 Video Capture Mode
Table 3-4. Error Correction by Protection Bits (continued)
Received F, V, and H Bits
Received P
3
-P
0
Bits
000
001
010
011
100
101
110
111
1011
010
-
010
010
-
101
010
-
1100
-
001
110
-
110
-
110
110
1101
001
001
-
001
-
001
110
-
1110
-
-
-
011
-
101
110
-
1111
-
001
010
-
100
-
-
-
The BT.656 format is an interlaced format consisting of two fields. The video port allows capture of one or
both fields. The captured image is a subset of each field and can be larger or smaller than the active video
region. The captured image position is defined by the VCxSTRT1 and VCxSTOP1 registers for field 1, and
the VCxSTRT2 and VCxSTOP2 registers for field 2. The VCXSTART and VCXSTOP bits set the
horizontal window position for the field relative to the HCOUNT pixel counter. The VCYSTART and
VCYSTOP bits set the vertical position relative to the VCOUNT line counter. This is shown in
HCOUNT increments on every chroma sample period (every other VCLKIN rising edge) for which capture
is enabled. Once VCOUNT = YSTART, line capture begins when HCOUNT = XSTART. It continues until
HCOUNT = XSTOP. A field's capture is complete when HCOUNT = VCXSTOP and VCOUNT =
VCYSTOP.
Figure 3-1. Video Capture Parameters
shows common digital camera standards and the number of fields per second, number of active
lines per field, and the number of active pixels per line.
48
Video Capture Port
SPRUEM1 – May 2007