cx25870 Conexant Systems, Inc., cx25870 Datasheet - Page 183

• Manufacturer Part Number: cx25870
• Description: Video Encoder With Adaptive Flicker Filtering And Hdtv Output
• Manufacturer: Conexant Systems, Inc.

100381B
Appendix A Scaling and I/0 Timing
Register Calculations
The calculated values are used to program the registers controlling the total active
pixels and lines in the input frame and the output field, as well as the vertical
scaling register and the clock PLL registers. These calculations assume pixel
resolution for synchronizing the graphics controller, master interface operation
unless otherwise stated, and require the following input values:
Tables A-1
Table A-3
Figures A-1
most common desktop active resolutions.
common overscan values for the 640 x 480, 800 x 600, and 1024 x 768 active
resolutions that enable dual display on both the VGA monitor and TV.
MFP—Minimum Front Porch Blanking in the Input in Clocks = max
(12, Controller_Minimum_Front_Porch_Blanking_Clocks);
MBP—Minimum Back Porch Blanking in the Input in Clocks = max
(4, Controller_Minimum_Back_Porch_Blanking_Clocks);
VOC—desired Vertical Overscan Compensation (e.g., 0.15)
HOC—desired Horizontal Overscan Compensation (e.g., 0.15)
V_ACTIVEI—Active Lines per Input Frame (e.g., 480 or 600 or 768)
H_ACTIVE—Active Pixels per Input Line (e.g., 640 or 800 or 1024)
ALO—Target Active Lines per Output Field (See
TLO—Total Lines per Output Field (See
ATO—Active Time per Output Line (See
TTO—Total Time per Output Line (See
details the constant software values depending on the video output.
and
through
A-2
Conexant
contain details of the supported video output formats.
A-8
illustrate allowable overscan compensation pairs for the
A49
Tables A-3
Table
Table
Table
A-3)
through
A-3)
A-3)
Table
A-27
A-3)
list the most
A-1