![](http://datasheet.mmic.net.cn/260000/PTM1300FBEA_datasheet_15959396/PTM1300FBEA_117.png)
Philips Semiconductors
Enhanced Video Out
PRODUCT SPECIFICATION
7-13
7.14
EVO OPERATING MODES
EVO operating modes belong to two groups as follows:
Video-refresh modes
Data-transfer modes
Data-transfer modes are further broken down into data-
streaming mode and message-passing mode.
The operating mode is set by the VO_CTL.MODE field
and the VO_CTL.OL_EN (overlay enable) control bit.
The VO_CTL.MODE field determines video-refresh,
message-passing or data-streaming mode. It further de-
fines the video image format and whether or not 2
×
hori-
zontal upscaling takes place. The OL_EN bit determines
whether a video-refresh mode has a graphics overlay
present. The modes are shown in
Table 7-4
.
7.15
VIDEO PROCESSING
If enabled, the TM1300 implements new functions for
chroma keying, alpha blending and programmable clip-
ping, as described in this section.
7.15.1
Alpha Blending
If
FULL_BLENDING = 1, the EVO provides full 129-layer
alpha blending of a background video image with a fore-
ground graphics overlay image. If either bit is 0, the EVO
implements the cruder 25% step alpha blending resolu-
tion of the TM1000. Alpha blending can operate in con-
junction
with
chroma
keying,
Section 7.15.2
.
Alpha blending combines a graphics overlay image with
the video image according to an alpha value provided
with each overlay pixel. The graphics overlay is taken
from a pixel-packed YUV 4:2:2+
α
data structure in mem-
ory. In the YUV 4:2:2+
α
format, each pixel has a single
α
-bit supplied as the LSB of the U and V pixels. The U
byte LSB corresponds to the alpha for pixel Y0, the V
byte LSB for pixel Y1, respectively. When the
α
-bit is ‘0’,
the ALPHA_ZERO register supplies the actual 8-bit
α
value. When the
α
-bit is ‘1’, the ALPHA_ONE register
supplies the 8-bit
α
value. In the YUV 4:2:2 format, only
one set of U and V values is supplied for the two Y pixels,
Y0 and Y1. In this case, the alpha bit in U0 determines
the alpha value for U, Y0 and V. The alpha blend bit in
V0 only sets the alpha value for Y1 and does not affect
the U or V values.
The EVO uses the 8-bit content of the selected alpha
blending register (ALPHA_ZERO or ALPHA_ONE) to
determine the amount by which the overlay plane is
merged with the image plane as follows. The least-signif-
icant 7 bits of the selected blending register encode 128
blending levels from 0 to 0x7F. The MSB is used to turn
on blending (MSB = ‘0’) or to select the overlay plane as
the only output (MSB = ‘1’), so all values between 0x80
and 0xFF select 100% overlay. Therefore, the total num-
ber of blending levels is 129: 128 variable blending val-
ues from 0 to 0x7F plus one ‘blending’ value from 0x80
to 0xFF for 100% overlay. An alpha value of 0 selects
100% image plane and 0% overlay. Similarly, a value of
0x40 selects 50% image and 50% overlay blending.
enabled
by
setting
EVO_ENABLE = 1
and
as
described
in
Table 7-4. EVO Operating Modes
Mode
Function
Explanation
Video-refresh modes
YUV 4:2:2C-1
×
YUV 4:2:2 co-sited, no scaling
YUV 4:2:2I-1
×
YUV 4:2:2 interspersed, no scaling
YUV 4:2:0-1
×
YUV 4:2:0, no scaling
Reserved
YUV 4:2:2C-2
×
YUV 4:2:2 co-sited, horizontal 2
×
upscaling
YUV 4:2:2I-2
×
YUV 4:2:2 interspersed, horizontal
2
×
upscaling
YUV 4:2:0-2
×
YUV 4:2:0, horizontal 2
×
upscaling
Reserved
Data-transfer modes
data
streaming
data with valid data pulse and level
timing signals
message
passing
STMSG and ENDMSG timing sig-
nals
Reserved
0
1
2
3
4
5
6
7
8
continuous transmission of raw 8-bit
9
transmission of raw 8-bit data with
0xA
—
0xF
1
Input Pixels: Y
Output Pixels: Y’
2
3
4
5
6
1
3
5
7
9
11
2
4
6
8
10
12
Y’=Y1
Y’=Y2
Y’=Y3
Y’=Y4
Y’=Y5
2N–1:
Y’=Y6
Y’=F(Y1,Y1,Y2,Y3)
Y’=F(Y1,Y2,Y3,Y4)
Y’=F(Y2,Y3,Y4,Y5)
Y’=F(Y3,Y4,Y5,Y6)
Y’=F(Y4,Y5,Y6,Y6)
2N:
Y’=F(Y5,Y6,Y6,Y5)
Figure 7-28. Mirroring pixels in 2x upscaling.