Texas Instruments TMS320DM648 manual 3 BT.656 Image Window and Capture, Video Capture Parameters

www.ti.com

BT.656 Video Capture Mode

	Table 3-4. Error Correction by Protection Bits					(continued)
				Received F, V, and H Bits
Received P3-P0Bits	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	-	-	-

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 Figure 3-1.

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'scapture is complete when HCOUNT = VCXSTOP and VCOUNT =

VCYSTOP.

Figure 3-1. Video Capture Parameters

Hcount=0
Ycount=1	Ystart
Xstart	Capture Image	Ystop
Xstop
Ycount=1		Field 1
	Ystart
Xstart	Capture Image	Ystop
Xstop
		Field 2

Table 3-5shows 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

Submit Documentation Feedback