Hardware description
Parameters:
Standard
: A code selecting the TV colour-encoding standard. Possible values
RC200VideoInStandardPALNTSC
or
RC200VideoInStandardSECAM
The first code selects PAL or NTSC and the second selects SECAM. The default
value is
RC200VideoInStandardPALNTSC
.
Timing:
1 or more clock cycles.
Description:
Selects which colour-encoding standard to expect at the selected input.
You need to call
RC200VideoInSetInput()
before using this macro. The video
input is capable of decoding both PAL and NTSC from the same setting.
5.12.4 Reading a pair of YCrCb pixels
extern macro proc RC200VideoInReadPixelPairYCrCb (
XPtr
,
YPtr
,
YCrCbPtr
);
Parameters:
XPtr
: Pointer to an
lvalue
of type
unsigned 9
.
YPtr
: Pointer to an
lvalue
of type
unsigned 9
.
YCrCbPtr:
Pointer to an
lvalue
of type
unsigned 32
.
Timing:
1 or more clock cycles (read blocks until data is ready).
Description:
Reads a pair of YCrCb encoded pixels from the video input selected by
RC200VideoInSetInput()
. YCrCb is the native output from the video decoder
and therefore requires the least hardware.
After the macro returns,
(*
XPtr
,
*
YPtr
) are the coordinates of the most recently
sampled pixel, which has the colour value (
*
YCrCbPtr
). Each pixel pair is
presented at most once (pixels can be missed if they are not read quickly enough),
at a rate of 6.75 MHz during the visible portion of the input video. The YCrCb data
is formatted as follows:
(*YCrCbPtr)[31:24] - Overall Cb (blue chrominance) value
(*YCrCbPtr)[23:16] - Left-hand pixel Y (luminance) value
(*YCrCbPtr)[15: 8] - Overall Cr (red chrominance) value
(*YCrCbPtr)[ 7: 0] - Right-hand pixel Y (luminance) value
The chrominance and luminance values follow the CCIR601 standard ranges. The
value in
XPtr
ranges from 0 to 718 (in 2-pixel increments) for an entire video line of
720 pixels. The value returned in
YPtr
varies from 0 to the number of visible lines
– 1: 0-575 for PAL and 0-479 for NTSC.
5.12.5 Reading a pair of RGB pixels
extern macro proc RC200VideoInReadPixelPairRGB (
XPtr
,
YPtr
,
LeftRGBPtr
,
RightRGBPtr
);
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