vpx3224d ETC-unknow, vpx3224d Datasheet - Page 28

• Manufacturer Part Number: vpx3224d
• Description: Video Pixel Decoders
• Manufacturer: ETC-unknow

28
VPX 3225D, VPX 3224D
2.10. Windowing the Video Field
For each input video field, two non-overlapping video
windows can be defined. The dimensions of these win-
dows are supplied via I
two windows allows separate processing parameters
such as filter responses and the number of pixels per line
to be selected.
External control over the dimensions of the windows is
performed by I
LoadTab). For each window, a corresponding WinLoad-
Tab is defined in a table of registers in the FP-RAM [win-
dow1: 0x120–128; window2: 0x12a–132]. Data written
to these tables does not become active until the cor-
responding latch bit is set in the control register FP-
RAM 0x140. A 2-bit flag specifies the field polarity over
which the window is active [vlinei1,2].
Vertically, as can be seen in Fig. 2–31, each window is
defined by a beginning line given in FP-RAM 0x120/12A,
a number of lines to be read-in (FP-RAM 0x121/12B),
and a number of lines to be output (FP-RAM
0x122/12C). Each of these values is specified in units of
video lines.
Fig. 2–31: Vertical dimensions of windows
# lines in,
# lines out
begin
Line 1
2
C writes to a window-load-table (Win-
2
Window 1
Window 2
C commands. The presence of
# lines in,
# lines out
begin
The option, to separately specify the number of input
lines and the number of output lines, enables vertical
compression. In the VPX, vertical compression is per-
formed via simple line dropping. A nearest neighbor al-
gorithm selects the subset of the lines for output. The
presence of a valid line is signalled by the ‘video active’
qualifier (or the corresponding SAV/EAV code in em-
bedded sync modes).
The numbering of the lines in a field of interlace video is
dependent on the line standard. Figs. 2–33 and 2–34 il-
lustrate the mapping of the window dimensions to the
actual video lines. The indices on the left are the line
numbers relative to the beginning of the frame. The in-
dices on the right show the numbering used by the VPX.
As seen here, the vertical boundaries of windows are de-
fined relative to the field boundary. Spatially, the lines
from field #1 are displayed above identically numbered
from field #2. For example: On an interlace monitor, line
#23 from field #1 is displayed directly above line #23
from field #2. There are a few restrictions to the vertical
definition of the windows. Windows must not overlap
vertically but can be adjacent. The first allowed line with-
in a field is line #10 for 525/60 standards and line #7 for
625/50 standards. The number of output lines cannot be
greater than the number of input lines (no vertical zoom-
ing). The combined height of the two windows cannot
exceed the number of lines in the input field.
Horizontally, the windows are defined by a starting point
defined in FP-RAM 0x123/12D and the length in FP-
RAM 0x124/12E. They are both given relative to the
number of pixels (NPix) in the active portion of the line
(Fig. 2–32) selected in FP-RAM 0x125/12F. The scaling
factor is calculated internally from NPix.
Fig. 2–32: Horizontal dimensions of sampling window
64 msec
H Begin
53.33 msec
H Length
N Pix
PRELIMINARY DATA SHEET
Window
Micronas