ADV601

–13–

REV. 0

VIDEO AREA REGISTERS

The area defined by the HSTART, HEND, VSTART and VEND registers is the active area that the wavelet kernel processes. Video

data outside the active video area is set to minimum luminance and zero chrominance (black) by the ADV601. These registers allow

cropping of the input video during compression (encode only), but do not change the image size. Figure 10 shows how the video area

registers work together.

VSTART

VEND

HSTART

HEND

ZERO

ZERO

ZERO

X, Y

ACTIVE VIDEO AREA

0, 0

ZERO

ZERO

ZERO

ZERO

ZERO

MAX FOR SELECTED VIDEO MODE

Figure 10. Video Area and Video Area Registers

HSTART Register

Indirect (Write Only) Register Index 0x02

This register holds the setting for the horizontal start of the ADV601’s active video area. The value in this register is usually set to

zero, but in cases where you wish to crop incoming video it is possible to do so by changing HST.

[9:0]

Horizontal Start, HST[9:0]. 10-bit value defining the start of the active video region. (0 at reset)

[15:10] Reserved (always write zero)

HEND Register

Indirect (Write Only) Register Index 0x03

This register holds the setting for the horizontal end of the ADV601’s active video area. If the value is larger than the max size of the

selected video mode, the ADV601 uses the max size of the selected mode for HEND.

[9:0]

Horizontal End, HEN[9:0].10-bit value defining the end of the active video region. (0x3FF at reset this value is larger than

the max size of the largest video mode)

[15:10] Reserved (always write zero)

VSTART Register

Indirect (Write Only) Register Index 0x04

This register holds the setting for the vertical start of the ADV601’s active video area. The value in this register is usually set to zero

unless you want to crop the active video.

To vertically crop video while encoding, program the VSTART and VEND registers with actual video line numbers, which differ for

each field. The VSTART and VEND contents must be updated on each field. Perform this updating as part of the field-by-field BW regis-

ter update process. To perform this dynamic update correctly, the update software must keep track of which field is being processed next.

[9:0]

Vertical Start, VST[9:0]. 10-bit value defining the starting line of the active video region, with line numbers from 1-to-625

in PAL and 1-to-525 in NTSC. (0 at reset)

[15:10] Reserved (always write zero)

VEND Register

Indirect (Write Only) Register Index 0x05

This register holds the setting for the vertical end of the ADV601’s active video area. If the value is larger than the max size of the

selected video mode, the ADV601 uses the max size of the selected mode for VEND.

To vertically crop video while encoding, program the VSTART and VEND registers with actual video line numbers, which differ for

each field. The VSTART and VEND contents must be updated on each field. Perform this updating as part of the field-by-field BW

register update process. To perform this dynamic update correctly, the update software must keep track of which field is being pro-

cessed next.

[9:0]

Vertical End, VEN[9:0]. 10-bit value defining the ending line of the active video region, with line numbers from 1-to-625

in PAL and 1-to-525 in NTSC. (0x3FF at reset—this value is larger than the max size of the largest video mode)

[15:10] Reserved (always write zero)