2.0 Functional Description
Fusion 878A
2.4 Video Scaling, Cropping, and Temporal Decimation
PCI Video Decoder
2-16
Conexant
100600B
2.4.2 Image Cropping
Cropping enables the user to output any subsection of the video image. The start
of the active area in the vertical direction is referenced to VRESET (beginning of
a new field). In the horizontal direction it is referenced to HRESET (beginning of
a new line). The dimensions of the active video region are defined by HDELAY,
HACTIVE, VDELAY, and VACTIVE. All four registers are 10-bit values. The
CROP register contains two MSBs of each register, while the lower eight bits are
in the respective HDELAY_LO, HACTIVE_LO, VDELAY_LO, and
VACTIVE_LO registers. The vertical and horizontal delay values determine the
position of the cropped image within a frame while the horizontal and vertical
active values set the pixel dimensions of the cropped image as illustrated in
Table 2-3. Scaling Ratios for Popular Formats Using Frequency Values
Scaling Ratio
Format
Total Resolution
(1)
Output
Resolution
(Active Pixels)
HSCALE
Register
Values
VSCALE Register Values
Use Both
Fields
Single
Field
Full Resolution
1:1
NTSC SQ Pixel
NTSC CCIR601
PAL CCIR 601
PAL SQ Pixel
780x525
858x525
864x625
944x625
640x480
720x480
720x576
768x576
0x02AA
0x00F8
0x0504
0x033C
0x0000
0x0000
0x0000
0x0000
N/A
N/A
N/A
N/A
CIF
2:1
NTSC SQ Pixel
NTSC CCIR601
PAL CCIR 601
PAL SQ Pixel
390x262
429x262
432x312
472x312
320x240
360x240
360x288
384x288
0x1555
0x11F0
0x1A09
0x1679
0x1E00
0x1E00
0x1E00
0x1E00
0x0000
0x0000
0x0000
0x0000
QCIF
4:1
NTSC SQ Pixel
NTSC CCIR601
PAL CCIR 601
PAL SQ Pixel
195x131
214x131
216x156
236x156
160x120
180x120
180x144
192x144
0x3AAA
0x3409
0x4412
0x3CF2
0x1A00
0x1A00
0x1A00
0x1A00
0x1E00
0x1E00
0x1E00
0x1E00
ICON
8:1
NTSC SQ Pixel
NTSC CCIR601
PAL CCIR 601
PAL SQ Pixel
97x65
107x65
108x78
118x78
80x60
90x60
90x72
96x72
0x861A
0x7813
0x9825
0x89E5
0x1200
0x1200
0x1200
0x1200
0x1A00
0x1A00
0x1A00
0x1A00
NOTE(S):
(1)
Including sync and blanking interval.