TM1100 Preliminary Data Book
Philips Semiconductors
13-16
PRELIMINARY INFORMATION
File: icp.fm5, modified 7/26/99
13.5.9.1
YUV Sequence Counter in YUV 4:2:2
Output Mode
For RGB output formats, the YUV data must be scaled to
YUV 4:4:4 format before conversion to RGB. The YUV
data in SDRAM is typically stored in YUV 4:2:2. This
means that the U and V data must be upscaled by 2 rel-
ative to the Y data to generate the internal YUV 4:4:4 for-
mat required for RGB conversion.
For the YUV 4:2:2 output code, the U and V data does
not need to be up scaled to 4:4:4. You would be scaling
up to YUV 4:4:4 only to decimate back to YUV 4:2:2. In
the YUV 4:2:2 output case, you want to use the U and V
pixels twice. This is done by having a half-speed mode
for the YUV Sequence Counter. In this mode, the se-
quence is U0, V0, Y0, Y1, U2, V2, Y2, Y3, etc. The U and
V are not up scaled by 2 relative to the Y component for
YUV 4:4:4 output, although they could be up scaled as
part of general up scaling of the image.
The YUV 4:2:2 Output mode also provides higher pro-
cessing bandwidth relative to YUV 4:4:4 up scaling. You
are processing half as many U and V pixels. The output
pixel rate is one pixel per 20 nanoseconds for the YUV
4:2:2 Output mode versus one pixel per 30 for conver-
sion to YUV 4:4:4. This can be used to provide some pro-
cessing performance improvement for very large images
at the expense of some chroma quality.
13.5.9.2
PCI Output Block Timing
The ICP generates pixels to the PCI interface at a peak
rate of 33 output megapixels per second in the RGB
T
o
PCI
5 Stage Multiplier-
Accumulator
Y, U, V LSBs
Reg
a
+2
RAM
a
+1
RAM
a
+0
RAM
a
-1
RAM
a
-2
RAM
Y Counter
Y LSB Counter
Buffers 0,1
Block FIFO
Filter Source Select
5-tap Filter
Reg
U Counter
U LSB Counter
Buffers 2,3
Block FIFO
Reg
V Counter
V LSB Counter
Buffers 4,5
Block FIFO
Reg
OL Counter
B, BX Counter
Buffer 8
Bit Mask
Buffers 6,7
Overlay
FIFO
Multiple
x
er:
Y
,
U
,V
Select
Mux
YUV
to
RGB
Con
ver
sion,
Formatting,
Alpha
Blending
&
Bit
Masking
YUV
Counter
Sequence
Pixel
Clock
Y, U, V Data FIFO Clocks
Mirr
or
Multiple
x
e
r
Y Mirror Cntr
U Mirror Cntr
V Mirror Cntr
Mux
RGB to SDRAM case
RGB to PCI case
Figure 13-16. ICP Horizontal Scaling for RGB Output Data Flow Block Diagram