BT.656 Video Capture Mode
Table 3–4. Error Correction by Protection Bits (Continued)
Received
Received
000
P
P
–P
–P
Bits
Bits
3
3
0
0
0111
100
1000
000
1001
–
1010
–
1011
010
1100
–
1101
001
1110
–
1111
–
3.2.3
BT.656 Image Window and Capture
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 cap-
tured 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
Figure 3–1.
HCOUNT increments on every chroma sample period (every other VCLKIN
rising edge) for which capture is enabled. Once VCOUNT = VCYSTART, line capture
begins when HCOUNT = VCXSTART. It continues until HCOUNT = VCXSTOP. A
field's
VCOUNT = VCYSTOP.
3-6
Video Capture Port
Received F, V, and H Bits
001
010
011
–
–
011
–
–
–
001
010
–
101
010
–
–
010
010
001
110
–
001
–
001
–
–
011
001
010
–
capture
is
complete
100
101
110
100
100
100
–
101
110
–
–
–
101
101
–
–
101
010
110
–
110
–
001
110
–
101
110
100
–
–
when
HCOUNT = VCXSTOP
111
–
–
111
101
–
110
–
–
–
and
SPRU629