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參數(shù)資料
| 型號： | SAA4978H |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 消費家電 |
| 英文描述： | Picture Improved Combined Network PICNIC |
| 中文描述： | SPECIALTY CONSUMER CIRCUIT, PQFP160 |
| 封裝： | 28 X 28 MM, 3.40 MM HEIGHT, PLASTIC, MS-022, SOT-322-2, QFP-160 |
| 文件頁數(shù)： | 14/56頁 |
| 文件大?。?/td> | 296K |
| 代理商： | SAA4978H |
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1999 May 03
14
Philips Semiconductors
Product specification
Picture Improved Combined Network
(PICNIC)
SAA4978H
This information can be used in combination with other
information on how to display the video source on the
screen. Such decisions are made entirely by the internal
microcontroller.
7.2.14
B
LACK BAR DETECTION
Black bar detection searches in the upper and in the lower
part of the screen to respectively the last black line and the
first black line. To avoid disturbances of Logos in the video,
measurements can be performed in only the horizontal
centre part of the lines.
7.2.15
B
US
C
FORMAT
(see Table 1)
The U and V samples from the 4 : 2 : 2 data are filtered
again by a [
1; 0; 9; 16; 9; 0;
1] filter, before being
subsampled by a factor of 2. Bypassing this function keeps
the data in the 4 : 2 : 2 format.
Should it be required to format the data to 8 bits, a choice
can be made between rounding and dithered rounding.
Dithered rounding may be applied in the sense that every
odd output sample has had an addition of 0.25 LSB
(relative to 8 bits) before truncation and every even output
sample has had an addition of 0.75 LSB before truncation.
In this way, normally, correct rounding is realized (no DC
shift). Especially for low frequency signals, the resolution
is increased by a factor of 2 by the high frequency
modulation. The phase of dithering is switched 180
°
from
line-to-line, field-to-field or frame-to-frame in order to
decrease the visibility of the dithering pattern.
This block also performs the subsampling for multi PIP,
with subsampling factors of 1, 2, 3 and 4.
Another output format at bus C is Differential Pulse Code
Modulation (DPCM) 4 : 2 : 2. This data compression
method is applied on the U and V channels, and gives a
50% data reduction. In this way it is possible to convert a
4 : 2 : 2 picture to 2f
H
using a single 12-bit wide field
memory. This format is especially useful for graphics
conversion with high amplitude and high saturation input
signals. The not connected output pins of bus C including
WEC and IEC (depending on the application) can be set to
3-state to allow short-circuiting of these pins at board
production. Short-circuiting at not connected outputs can
not be tested by BST. For outputs in 3-state mode it is not
allowed to apply voltages higher than V
DDO
+ 0.3 V.
7.2.16
B
US
D
REFORMATTER
:
THE VARIOUS INPUT
FORMATS ARE ALL CONVERTED TO THE INTERNAL
9
BITS
4 : 2 : 2 (see Table 1)
Bus D can handle 4 : 1 : 1 external 8 or 9 bits, 4 : 2 : 2
external 8 or 9 bits, 4 : 2 : 2 internal 9 bits and DPCM
4 : 2 : 2.
Bus D is selectable in 1f
H
and 2f
H
mode. In 1f
H
mode the
internal input can also be used.
For dithered 8-bit luminance signals an undither block is
provided that restores the 9th bit for low frequency and low
noise. This is needed before the peaking circuit to prevent
amplification of the
1
2
f
s
dither modulation.
In the event of 8-bit inputs, the LSB of the input bus should
be externally connected to a fixed logic level.
In the event of a 4 : 1 : 1 input, the U and V channels are
reformatted and upsampled by generating the extra
samples with a
1
16
×
[
1; 9; 9;
1] filter. The other U and V
samples remain equal to the original 4 : 1 : 1 sample
values.
7.2.17
P
EAKING
Peaking in the SAA4978H can be used in two ways:
1.
The first way is to give the luminance a linear boost of
the higher frequency ranges, which makes no
distinction between small and large details or edges.
2.
The second way is to use the peaking dynamically, in
order to boost smaller details and provide less gain on
large details and edges. The effect is detail
enhancement without the creation of unnaturally large
overshoots and undershoots on large details and
edges.
Basically, the three peaking filters (1 high-pass and
2 band-pass) filter the incoming luminance signal.
The high-pass filter is made with [
1; 2;
1] coefficients,
giving a maximum throughput at
1
2
f
s
(equals 8 MHz).
The first band-pass filter has [
1; 0; 2; 0;
1] coefficients,
giving a maximum throughput at
1
4
f
s
(equals 4 MHz).
The second band-pass filter has a cascade of
[
1; 0; 0; 2; 0; 0;
1] and [1; 2; 1] coefficients, giving a
maximum throughput at 2.38 MHz.
With a separate gain control on each of the peaking filters
[possible gain settings of (0,
1
16
,
2
16
,
3
16
,
4
16
,
5
16
,
6
16
and
8
16
)], a desired frequency characteristic can be
obtained with steps of maximum 2 dB gain difference at
the centre frequencies.
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| SAA4979H | Sample rate converter with embedded high quality dynamic noise reduction and expansion port |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| SAA4979H | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Sample rate converter with embedded high quality dynamic noise reduction and expansion port |
| SAA4981 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Monolithic integrated 16 : 9 compressor |
| SAA4981T | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Monolithic integrated 16 : 9 compressor |
| SAA4990 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Progressive scan-Zoom and Noise reduction IC PROZONIC |
| SAA4990H | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Progressive scan-Zoom and Noise reduction IC PROZONIC |
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