Philips Semiconductors
Enhanced Video Out
PRELIMINARY SPECIFICATION
7-11
7.13.1
YUV 4:2:2 Interspersed to YUV 4:2:2
Co-sited Conversion
The EVO accepts data from SDRAM in either YUV 4:2:2
co-sited, YUV 4:2:2 interspersed, or YUV 4:2:0 inter-
spersed formats. If the input data is in YUV 4:2:2 or YUV
4:2:0 interspersed format, interspersed-to-co-sited con-
version is performed to generate co-sited output. The
EVO uses a 4-tap, (
–
1, 5, 13,
–
1)/16 filter to perform this
conversion on the U and V chroma data.
Figure 7-24
shows
an
example
of
interspersed
to
co-sited
conversion.
7.13.2
YUV 4:2:0 to YUV 4:2:2 Co-sited
Conversion
YUV 4:2:0 to YUV 4:2:2 conversion is a variation of YUV
4:2:2 interspersed-to-co-sited conversion. The YUV
4:2:0 format has the U and V pixels positioned between
lines as well as between pixels within each line. It also
has half the number of U and V pixels compared to YUV
4:2:2 formats. The EVO converts YUV4:2:0 to YUV 4:2:2
co-sited by using the U and V chrominance pixel values
for both surrounding lines and converting the resulting U
and V pixels from interspersed to co-sited format. This is
shown in
Figure 7-25
. For true vertical re-sampling of U
and V, the PNX1300 ICP unit can be invoked on U and
V to convert from YUV 4:2:0 to YUV 4:2:2 interspersed.
7.13.3
YUV-2x Upscaling
In the YUV-2
×
modes, the EVO performs 2
×
horizontal
upscaling of the YUV data from SDRAM. No vertical up-
scaling is performed. The width of the result image
(IMAGE_WIDTH) should be an even number. Upscaling
is performed by 4-tap filtering. For all 3 memory formats,
Y luminance data is upscaled using a (
–
3,19,19,
–
3)/32
filter to generate the missing output pixels. Output pixels
at the same location as the input pixels use the corre-
sponding input pixel values, as shown in
Figure 7-26
.
The U and V chrominance values are generated in the
same way as the Y luminance signal for 2
×
upscaling, as-
suming that both the input and output use YUV 4:2:2 co-
sited chrominance coding. The U and V output pixels at
the same location as the U and V input pixels use the cor-
responding input pixel values. The U and V output pixels
between the U and V input pixels are generated using
the
(
–
3,19,19,
–
3)/32
filter,
as
shown in
Figure 7-26
.
If the input chroma is interspersed, a (
–
1,13,5,
–
1)/16 fil-
ter is used to generate the U and V output pixels that are
displaced by half a Y pixel from the U and V input pixels,
and a (
–
1,5,13,
–
1)/16 filter is used to generate the addi-
tional upscaled U and V output pixels that are displaced
by 1. 5 pixels from the U and V input pixels. This is shown
in
Figure 7-27
.
7.13.4
Pixel Mirroring for Four-tap Filters
The EVO uses a 4-tap filter for upscaling and for convert-
ing from interspersed to co-sited format. One extra pixel
is needed at the beginning and two at the end of each
line processed by this filter. These pixels are supplied
WIDTH pixels
H
pix0
pix1
pix2
pix
W
–
1
Y_BASE_ADR
WIDTH/2 pixels
H
pix0
pix2
U_BASE_ADR
(Repeated for
V_BASE_ADDR,
V_OFFSET)
Y_OFFSET
U_OFFSET
Figure 7-22. Image storage in planar memory format
for YUV 4:2:2.
Figure 7-23. YUV 4:2:2+alpha overlay format.
OVERLAY_WIDTH pixels
O
pix0
pix1
pix2
pix
W
–
1
OL_BASE_ADR
OL_OFFSET
Y0
U0
Y1
V0
YUV 4:2:2+
α
α
α
Chrominance (U,V)
samples
Luminance
samples
Input Pixels: YUV
Output Pixels: YU
’
V
’
Co-sited Chrominance Output:
U
’
,V
’
= (
–
1,5,13,
–
1)/16
×
U,V
Figure 7-24. YUV interspersed to co-sited conversion.