Bt.656 Image Window And Capture; Video Capture Parameters - Texas Instruments TMS320DM648 User Manual

BT.656 Video Capture Mode
Received P -P Bits
3 0
1011
1100
1101
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 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.
Table 3-5 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
Table 3-4. Error Correction by Protection Bits (continued)
000 001
010 -
- 001
001 001
- -
- 001
Figure 3-1. Video Capture Parameters
Hcount=0
Ycount=1
Ystart
Xstart
Capture Image
Xstop
Ycount=1
Ystart
Xstart
Capture Image
Xstop
Received F, V, and H Bits
010 011 100
010 010 -
110 - 110
- 001 -
- 011 -
010 - 100
Ystop
Field 1
Ystop
Field 2
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101 110 111
101 010 -
- 110 110
001 110 -
101 110 -
- - -
Figure 3-1.
SPRUEM1 – May 2007
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