
Rev. 2.0, 09/02, page 128 of 366
YCbCr data
(video capture)
RGB
=
1
UGM
RGB
=
0
VWRY
=
1
YCbCr/RGB
conversion
circuit
RGB data
(display)
VWRY
=
2
YCbCr/RGB
conversion
circuit
Figure 3.67 Conversion of YCbCr Data into RGB Format
When the first-stage conversion circuit is selected by setting the RGB bit in VIMR to 1, the
YCbCr data sent from the video decoder is converted into RGB data for storage in the UGM.
When the second-stage conversion circuit is selected by setting the VWRY bit in DSMR2 to 1,
the YCbCr data sent from the video decoder is converted into RGB data when the video screen
is displayed. This makes it possible to store data in either the YUV or RGB format.
When the first-stage circuit is applied to store RGB data in the UGM, the stored data can provide
multi-valued source data for use in drawing. When the foreground or background screen is
specified as being in the 16-bit/pixel mode, the RGB video data in a given screen area can be
directly captured for display other than on the video screen. When the second-stage conversion
circuit is used, the YCbCr data in the video capture area may be captured by the CPU for display
elsewhere.
15
10
0
11
4
5
G (5 bits)
B (5 bits)
R (5 bits)
Figure 3.68 The RGB Data Format (16 Bits/Pixel)
3.7
Video Display Function
3.7.1
Video Screen Display
Setting the VWE bit of display mode register 2 (DSMR2) places the data from the video-capture
area (VSA0 to 2) indicated by VID of the video-capture mode register (VIMR) on the video
screen in 16-bit/pixel mode. When the video-capture function is in operation, the area read for
display as the current screen is automatically switched according to the specification in VID.
The position at which the video screen is displayed is specified by the video display start
position register. Before the VWE bit is set to 1, the initial value should be set to the video
display start position register. The display size is specified by the VSIZEX and VSIZEY bits.
The data is displayed on an independent window (video screen).
Set a display position within the display area specified by DSX/DSY. The size of video screen is
the same as that of a captured area. In the non-interlace display mode, the video image can be