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24 Chapter 4: Hardware reference
To grab and switch between Y/C and composite/monochrome video sources,
allocate two different digitizers: one with a DCF for Y/C video sources and one
with a DCF for composite/monochrome video sources. For each allocated
digitizer, specify the input channel of the required video source using the MIL-Lite
function MdigControl() with M_CHANNEL; the channel numbering scheme
is based on the number of available channels for the type of input (DCF type), as
opposed to all available channels. Then, specify the appropriate digitizer when
performing the grab (MdigGrab()).
Low-pass filter
The input low-pass filtering stage is used to limit high frequency noise and aliasing
effects at the input of the decoder. The filters used on Matrox CronosPlus are
4th order Butterworth filters with a cut-off frequency of 8 MHz.
Video decoder
A multi-standard video decoder is used to convert NTSC and PAL analog video
signals that are composite (CVBS) or component (Y/C) to digitized component
video. The decoder supports BGR 8:8:8:8 (32-bit), BGR 8:8:8 (24-bit), and YUV
4:2:2 output pixel formats. Note that YUV 4:2:2 output pixel formats are grabbed
as YUYV.
The video decoder also features automatic gain control (AGC). However, you can
disable this feature using the MIL-Lite function MdigControl() with
set to
.
M_GRAB_AUTOMATIC_INPUT_GAIN
M_DISABLE
The video decoder also features an adaptive multi-line comb filter for better Y/C
separation, as well as an on-chip scaler, which can reduce the video image size in
both horizontal and vertical directions independently. The full resolution can be
scaled down to any value between 1 and 1/64. The video decoder can also crop
the image to the required width and height, as well as flip the image vertically
and/or horizontally.
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